- Ultimate Guide to Solar Energy System Operations, Maintenance, and Troubleshooting
One of the advantages of solar energy systems is that it is very easy to operate, maintain, and troubleshoot even for simple homeowners like you that don’t have experience in electrical installations. Solar energy systems are very simple and don’t require you to exert much effort once you already have one on your home. However, it is still important to give a little bit of your time into operating, maintaining, and troubleshooting your system to ensure that it can continue to produce energy for its lifetime of 25-30 years. If you already have a solar energy system on your home or if you are planning to have one installed but you are worried that it might be very difficult to operate, maintain and troubleshoot it, this is the right place for you! In here, you will find everything that you will need to know in order to properly operate, maintain, and troubleshoot a solar energy system. Operations Turning the system on/off Solar energy systems automatically turn on in the morning and off at night. As the sun starts to rise in the morning, the solar panels get a low amount of irradiance from the sun, which causes them to produce a voltage and current. The values for the produced voltage and current will then reach a level that is enough to turn on the system’s inverter as the sun continuously rises in the sky. This turns on the inverter, and thus, the whole system. As the sun sets in the afternoon, the irradiance that reaches the solar panels will continuously decrease, and eventually, its voltage and current levels will fall below the level that is required to keep the inverter on. The inverter then shuts down along with the whole system. Monitoring the energy production Probably the most satisfying feeling in having a solar energy system is monitoring its energy production. Take note that this is not required for the system to operate, which means that it will continue to produce energy whether you monitor its energy production or not. However, it is still best to do so for you to really feel the value of your investment and be satisfied with it. Different solar energy systems will have different ways to monitor the system production, depending on the brand and type of the inverter that was used on your system. For those that use string inverters, you can directly monitor the system’s energy production by looking at the small LCD screen on the inverter itself. Usually, you will also have the option of monitoring energy production through a mobile app or a website. Solar monitoring systems will usually let you see 4 system parameters: DC and AC voltages, DC and AC currents, power production in kilowatt(kW), and energy production in kilowatt-hour(kWh). However, as the owner of the system, you will only be interested in the power and energy production values as these will be the ones used to measure your system’s overall performance. Measuring system performance As we have mentioned in the section on monitoring the energy production, as the owner of the system, the only important parameters to look at are the power and energy production values. This is because, with these two values, you will be able to measure your system’s performance. Every solar energy system has a maximum power capacity that it can produce. During optimal weather and system conditions, your system should produce the same amount as this value. By monitoring the power that your system is producing and comparing it to the maximum, you can already get an idea of how well your system is performing. Your system’s energy production is the most important parameter to monitor because this directly translates to savings on your monthly electric bills. From this, you will get an idea of the total savings that you will get from your next electric bill. Operating in power outages During a power outage (or what is referred to as a brownout here in the Philippines), an on-grid solar energy system will automatically stop producing energy and shut itself down. This is a safety measure that is required to protect the personnel that might work on the electrical lines near your house because they would not know that the electrical lines are still energized. Operating with fluctuations in the utility electricity Solar energy systems are already designed to still operate despite having fluctuations in the electricity from the utility as long as these fluctuations are within set limits. This includes fluctuations in voltage and frequency and only means that you would not have to worry about these things as the system can manage and take care of itself in these situations. Maintenance Ensuring that the wiring is in optimum condition This may sound daunting at first, but it is simply just a matter of checking the condition of the wiring systems and ensuring that everything is in order and there are no damages. Inside your house, check the conduits and ensure that everything is nice and tight. Also, make sure that there are no physical damages, especially in the entry and exit points of the wires. In the afternoon, touch the wires that are going to the inverters to check if they are heating up too much. Overheating wires are usually a sign of electrical faults or undersized wires. For the wiring of the solar panels, you will have to climb your roof and look underneath them. Make sure that there are no loose wirings and everything is secured by cable ties. Also, make sure that no part of the wire is in contact with the roof. Lastly, ensure that each solar panel’s MC4 connector is connected tightly connected. Take note that when connecting the solar panel’s MC4 connectors, you will hear a clicking sound as a sign that a reliable connection was made. Ensuring that the communication system is in optimum condition If the communication system uses Wi-Fi, maintaining it would be much easier as you would just have to check if the communication line is active and that the inverter is able to send real-time data that you can monitor. For those that use a LAN connection, just make sure that the data cable is tightly connected to the inverter and your connection module. Also, make sure that the cables are nice and tight and have no visible physical damages. Cleaning the solar panels Solar panels can accumulate dust and other debris while being on your roof for a long time. This means that you will need to clean it from time to time. However, the frequency of which you need to clean them depends on many factors like how dusty is your area, how strong the wind blows, etc. Here in the Philippines, we have a rainy season that can help clean the solar panels, which is an added bonus. Preventing wiring faults Wiring faults mostly happen when the wire’s rubber insulation gets pierced or torn and the copper inside of it gets in contact with other parts of the system. This is dangerous as it can energize other parts of the system, electrocute someone or start a fire. Therefore, it is very important to avoid this from happening. Make sure that wires are not in contact to sharp metal edges, specifically with the wires that are coming down from your roof. Also, be aware of how much the wires of your sytem are bent because overbending them can cause the copper inside of it to break and lose their electrical connection. Ensuring that the inverter is in optimum condition It is best to consult with the manufacturer’s recommendations regarding the maintenance of the inverter. Do not be worried, however, because these are usually simple steps and actions that can be done by everyone without needing to open the inverter. If your inverter has a fan, these are usually removable and needs to be cleaned from time to time to ensure proper air circulation inside the inverter. Also, touch the outside of your inverter and make sure that it is not getting too hot. An inverter that is becoming too hot is usually a sign of a defect that may eventually lead to complete breakdown of the unit. Lastly, make sure that your inverter is free from dust by wiping it with a dry cloth or rag. Ensuring that the circuit breakers or disconnects(switches) are in optimum condition Maintenance of the circuit breakers and disconnects is usually just done through visual inspection and does not require you to touch them. This is because circuit breakers or disconnects(switches) may still be energized even in the open or off position and is still an electrical hazard. Also, make sure that the wires coming in and out it are nice and tight. Troubleshooting Low system production If your system is not producing as much as you expects it to be, it might be encountering problems that you must determine and fix right away. If its energy production is significantly lower than its estimated energy production, some solar panels or even whole strings of solar panels themselves may be disconnected from the inverter. Check each solar panel and make sure that its MC4 connectors are tightly connected. Also check the point where the solar panels or strings of solar panels connect to the inverter because they might be disconnected here. Another cause of low energy production is the accumulation of dust and debris or trash on your solar panels. This can easily be found out by doing a visual inspection. You can clean the solar panels using water and a mop(make sure that it is clean first), rag, or sponge. Lastly, observe your surroundings to check if there may be any tall structure that causes shading. Shading can significantly decrease the energy production of solar panels and should be avoided at all costs. No monitoring data First, check if the inverter is still transmitting data by monitoring the system’s production through the app or website. If real-time data is not available, this means that there is a problem with your communication system. If it is connected through Wi-Fi, check your Wi-Fi router for problems in your network or internet connection. On the other hand, if it uses a LAN connection, make sure that the data cables are properly connected on both ends. Also look for signs of physical damage to the cables that may cause your system to stop transmitting data. System faults System faults are any kind of fault that your system can experience. These are usually detected by the inverter and communicated to you, the homeowner, through an error message or a fault code that is displayed on the inverter’s LCD screen or through your monitoring system (app or website). For fault codes, you will need to check the manufacturer’s notes on what these fault codes mean for you to determine the appropriate action to remedy the problem. Overheating Overheating, whether on the wires or on the inverter itself, is always not good because it can be a sign that something is wrong within them. If not taken care of immediately, it can lead to total system breakdown or may even be a fire hazard. If you notice this on your system, it is best to turn it all off first, figure out what is causing it and fix the problem before turning it on again. Component defects Defects on your solar panels and/or inverter are covered by manufacturer warranties. Report any defects that you find to your solar installer for them to report it directly to the manufacturer and arrange for a replacement.
- Most Frequently Asked Questions(FAQ) About Solar
FAQ Table of Contents Solar Energy System Basics What is solar energy? What’s better? Solar or wind power? What are the different types of solar energy systems? Do I have to go off the grid when I switch to solar energy? How does solar energy benefit the environment? How long will my solar energy system last? Why should I go solar now? Aren’t innovative new technologies on the way? Why should I install a solar energy system on my home or business? I want to go off-grid, would you recommend this? What are the different types of solar inverters? About Solar Panels Will my solar panels withstand extreme weather conditions? Monocrystalline and Polycrystalline, what’s the difference and which one should I pick? What is solar panel efficiency and do I need a solar panel with high efficiency? What are the different types of solar panels? Do solar panels work in a blackout? Will I ever need to replace my solar panels? How do solar panels actually work? Energy Production Will solar panels produce the same amount of electricity all year long? What is net metering? Will my solar panels generate electricity during cloudy or rainy days? What about at night? Is solar energy reliable and powerful enough for my home or business? Financials Will solar pay for itself? How Much Does a Solar Energy System Cost? Will solar panels raise my home or business’ property value? How soon will I notice a difference in my electricity bills after switching to solar energy? How much will I really save on my electricity bills every month? How will switching to solar energy help me budget better? Installation What is the best option for installing solar panels with my budget? Will installing solar panels damage my roof? How long do solar panels take to install? Do you have to rewire my house? How will I know if my property is a good candidate for solar panels? What size solar energy system should I get? Do I need to replace my roof before installing solar? What happens during the solar installation process? How much roof space will I need for a solar energy system? Can I install solar panels on my property myself? What should I do now if I want to increase my system size later? Operations and Maintenance How much will solar panel maintenance cost? Are solar panels difficult to operate and maintain? How will I know if a solar energy system is working? Is a solar energy system noisy? How do I check my solar energy system’s performance and kW generation? Is my solar system covered by a warranty? Do I need to clean my panels? Solar Energy System Basics 1. What is solar energy? Solar energy simply refers to the energy from the sun. It is one of the most prominent renewable energy technologies today along with wind energy and has the biggest potential of being the energy of the future. Since the sun shines every day, solar energy is renewable, which means that it will never run out of fuel. It also doesn’t emit any greenhouse gases during its operation, making it a cleaner alternative to traditional fossil fuel energy sources. Lastly, solar energy has become the cheapest energy source today, beating wind, hydroelectric, coal, gas, and nuclear energy. 2. What’s better? Solar or wind power? Solar and wind energy are actually the 2 cheapest energy sources today, beating hydro, coal, gas and nuclear and are currently looking to be the best replacements for dirty fossil fuels as an energy source. In fact, did you know that it is now very common to have negative electricity prices in Germany because of their abundance of solar and wind energy? In terms of what is better, it is hard to objectively comment about this since we are a solar company, but what we can say is that solar energy is the only energy source among all others that has the advantage of being modular, which means that it can be implemented as a form of distributed energy generation. All the other energy sources, including wind, produce energy on large power plants. This is what we call a centralized energy generation. In contrast, solar energy can be installed virtually anywhere and power individual homes, which is what we mean by distributed energy generation. An advantage of distributed energy generation is the potential for individual homeowners to be independent power producers themselves. This can easily be achieved by installing solar panels on your roof. 3. What are the different types of solar energy systems? There are 2 types of solar energy systems, on-grid and off-grid systems. The on-grid system is the most commonly installed because they don’t have batteries and are therefore cheaper, simpler, easier to operate, and maintain, and more cost-effective. Its disadvantages, however, is that you are still connected to the grid and you will still be affected by power interruptions and brownouts. On-grid systems also require the use of a net meter, which will allow you to sell the excess energy from it to the grid. On the other hand, with an off-grid system, you will then be disconnected from the grid and will just rely on your solar panels and batteries for your electricity supply. During the morning, your solar panels are oversized to produce more energy than your daytime consumption. The excess energy is then used to charge your batteries to be used at night. We at Andal Solar always recommend our clients to have an on-grid solar energy system instead especially if their house already has an existing utility connection because it is just much, much cheaper. In fact, for the same system size, the cost of off-grid systems can be twice as much. Also, off-grid systems must be able to supply for your total consumption, so you will need a bigger system size (and of course, a bigger investment) of an off-grid system. This is in contrast to on-grid systems, where you can adjust your desired system size based on your budget or the amount of savings that you would want to have. 4. Do I have to go off the grid when I switch to solar energy? When you already have an existing utility connection on your house, it is always better to have an on-grid system instead of an off-grid one because it is significantly cheaper and simpler. In faraway places that do not have a utility connection yet, sometimes it is even cheaper to pay Meralco or your electric cooperative to put up a line to your house and have an on-grid system instead of an off-grid system. Aside from being more expensive, off-grid systems must also be oversized to compensate for the rainy and low irradiance months. You wouldn’t want to run out of energy from your batteries in the middle of the night because they have not been charged well in the rain. And if this is the case, in the summer, you will then have an excess of energy since your system is oversized for your consumption, which is a waste. 5. How does solar energy benefit the environment? The number 1 cause of global warming is the Carbon Dioxide that we release in the atmosphere when we burn fossil fuels for energy. Solar energy, on the other hand, is clean and does not emit any form of waste into the environment. By using a solar energy system, you reduce your reliance on electricity from the grid, which is mostly generated by burning coal. In your own little way, you will reduce our total Carbon Dioxide emissions and help our planet recover from the damage that was already done. 6. How long will my solar energy system last? Solar energy systems are rated to last for 25 to 30 years. However, some of the systems that were first installed have been reported to last for even more! This just means that having a solar energy system will really be a long-term investment and you will be able to enjoy savings from your monthly electric bills for many, many years to come. It is even more amazing because you will be less affected by power hikes and increases in electricity prices due to inflation for the lifetime of the system. Can you compare the amount of your electric bill 25 years ago to what you have now? There is a huge difference, right? Well, 25 years from now, the monthly savings that you will get from a solar energy system would have also increased by roughly the same percentage! 7. Why should I go solar now? Aren’t innovative new technologies on the way? There is a saying that goes like this: “The best time to plant a tree is 20 years ago. The next best time is now.” Since solar energy is also a long-term investment, with a lifetime of 25-30 years, we can think of the same thing with it. Also, climate change is becoming worse, giving us more and more extreme weather calamities every year. And since climate change works as a positive feedback loop, which means that most of its effects further worsens climate change, every year that we don’t act is very precious. 8. Why should I install a solar energy system on my home or business? Because of the savings that you can get from your monthly electric grid, you can also view solar energy as a financial investment. Yes, you pay a large amount of money upfront, but you will get it all back in 5 to 7 years. Since the lifetime of a solar energy system is at least 25 years, the savings that you will get from year 6 or 8 up until the 25th year can already be seen as the income for your investment. The good thing about this type of investment is that it is basically a no-lose investment. Investing in a small business has a danger of the business failing to make a profit, investing in stocks or foreign exchange has a danger of you losing all of your money, but with solar energy, you are sure that the sun will rise the next day and will produce energy. The only danger in investing in a solar energy system is having a substandard system installed by an unprofessional solar company. 9. I want to go off-grid, would you recommend this? We don’t recommend having an off-grid system because it is much more expensive, complex, and harder to operate and maintain. Aside from this, the system must be oversized to still be able to supply enough energy on rainy and/or cloudy days. This means that you will need to have a larger system size and invest a lot more. Finally, if you really want the best value for your money, an on-grid system is the right way to go because the ROI for this type of system is only 5-7 years while it doubles to 11-13 years for off-grid systems. 10. What are the different types of solar inverters? There are 2 types of inverters that can be used for residential solar installations: string inverters and microinverters. Among the 2, string inverters were the more commonly used for installations as this is the older technology that has been used ever since the first solar installations. On the other hand, microinverter technology is newer and is just becoming popular with solar companies. With string inverters, solar panels are connected in series to form strings. These strings of solar panels are then connected to the input of the inverter. The disadvantage of this is that strings of solar panels work together in a way that every solar panel in the string only performs as well as the worst-performing one. This means that if one solar panel is shaded, all of the solar panels in the string will be affected. Microinverters, as their name suggests, are smaller than the traditional string inverters. They are also installed on the roof under the solar panels while having only 1 or 2 solar panels connected to them. They have the advantage of being more efficient, being able to monitor the energy production of each solar panel and because the solar panels are not anymore connected in a string, they won’t suffer as much due to shading compared to if you use string inverters. Another difference between the two is that string inverters only have a lifetime of 10-15 years while microinverters’ lifetime is 25 years. Remember that the lifetime of solar panels is also 25 years. This means that string inverters will need to be replaced one or two times over the lifetime of the solar panels. About Solar Panels 1. Will my solar panels withstand extreme weather conditions? Extreme temperatures do not necessarily damage solar panels, but they affect the solar panel’s efficiency. When solar panels get hot, they become less efficient, while when they get cold, they become more efficient. Another type of extreme weather condition that solar panels are designed to withstand is hail. On an average, hailstorms drop hail that is ¼ to ½ inch thick at a speed of 32 kilometers per hour. However, solar panels are even designed to withstand a hail of up to 1 inch thick and a speed of 80 kph. In terms of heavy wind and typhoons, solar mounting systems can withstand winds of up 250 kph. However, take note that these are mounting systems that are designed specifically for solar panel installations. Some installers, especially here in the Philippines, make their own mounting using L bars and other types of metal parts that can easily be manufactured even in small metal shops. These are dangerous because they are not designed specifically for solar installations, did not undergo any mechanical calculations or studies, and are prone to galvanic corrosion(rusting). Lastly, it is a common concern for homeowners that their solar panels might be hit by lightning. However, having solar panels almost pose no additional risks in terms of being hit by lightning. The likelihood of something being hit by lightning increases as it gets taller or higher but solar panels are only effectively a few inches higher than your roof. In fact, if you have a TV antenna on your roof, that would still be more likely to be hit by lightning than your solar panels. 2. Monocrystalline and Polycrystalline, what’s the difference and which one should I pick? Monocrystalline and polycrystalline refers to the material that the solar panel is made of. Theoretically, monocrystalline solar panels are better because monocrystalline Silicon is a more “pure” type of crystalline Silicon, hence, the name mono- or one- crystalline. In solar panels, monocrystalline ones are more efficient and have better temperature characteristics than polycrystalline solar panels. However, these differences are not really very significant when comparing monocrystalline and polycrystalline solar panels in the market today. If you want the best type of solar energy system for your home, you can ask your solar company to use monocrystalline solar panels on your installation. Take note, however, that the increase in energy yield and savings that this will bring will not be very significant. 3. What is solar panel efficiency and do I need a solar panel with high efficiency? As we may all already know, energy can not be created out of nothing, it can only be converted from one form to another. With this, efficiency in any energy generating devices refers to the ratio of output energy, which is electricity, to the input energy, which is the fuel used. For solar panels, efficiency refers to how much electricity can be produced compared to the solar energy input. However, a better and more practical way to think about it is that a higher efficiency solar panel will produce more power for the same roof area compared to a lower efficiency one. This means that if you have a limited roof space and you want to get the most solar energy out of it, you have to have solar panels with high efficiency. If you have ample roof space, however, you should not be concerned too much about the solar panel’s efficiency. 4. What are the different types of solar panels? There are 2 main types of solar panels: monocrystalline and polycrystalline solar panels. This refers to the type of silicon material that is used to create solar cells. A quick and easy way to distinguish between the two is with their color. Monocrystalline solar panels are black, while the polycrystalline ones are blue. Monocrystalline is the superior type of solar panel among the two not only in terms of efficiency and energy production but also in terms of its temperature characteristics, which means that it does not suffer as much reduction in energy production with increases in temperature compared to polycrystalline solar panels. It is better to take a look at the proposal from your solar company to know beforehand the type of solar panel that will be installed on your roof. If you want a higher-quality system, you can request to have monocrystalline solar panels installed on your roof. 5. Do solar panels work in a blackout? Off-grid systems are unaffected by blackouts since they are disconnected from the electric grid. On-grid systems, however, will automatically shut down during blackouts as a safety feature, even if it can still produce energy. This is because of 2 reasons. The first is that if your solar energy system keeps on producing energy during a blackout, the energy that it produces will just spread to your neighbor’s houses, leaving a very little amount for yourself. Lastly, electrical linemen or personnel may work on the electric lines near your home during the blackout and not know that the lines are energized. This causes a severe safety issue for them, so on-grid inverters are required to shut itself down in these cases. 6. Will I ever need to replace my solar panels? Solar panels are made to last for at least 25 years while being exposed to the harsh outside elements. They are even designed to withstand a hail of up to an inch in and size falling at a speed of 50 miles per hour. This means that solar panels can definitely last for a long, long time even without repair and much maintenance. As a testament to this, solar panel manufacturers even give a 10-year product warranty and a 25-year performance warranty for their products. The product warranty covers problems regarding the quality of the solar panel and its integrity. This includes manufacturing defects, whether physical or electrical and premature wear and tear, among others. The performance warranty, on the other hand, is a manufacturer’s guarantee that the solar panel will still produce 90% of its rated power at 10 years and 80% at 25 years. After 25 years, it does not mean that the solar panel will stop producing power anymore, it is just not guaranteed anymore how more years it will be able to keep producing power and up to how many more years. This is why the rated lifetimes of solar energy systems are also set to 25 years. It is important to note, however, that the string inverters that are most commonly used by most solar installers can only last from 10-15 years. This means that within your solar energy system’s rated lifetime of 25 years, you will have to replace your inverter at least once and even up to 2 times. Based on our experience, this is something that most solar companies don’t mention to their customer which is not a good practice. We at Andal Solar use microinverters with a lifetime of 25 years, which means that you don’t have to replace it over the lifetime of the whole system. 7. How do solar panels actually work? Solar energy converts sunlight into electricity through the use of the photovoltaic or PV technology that is used by a solar panel. Solar panels produce DC electricity, which is why they need an inverter to convert this to the same AC electricity that we use in our homes. They are usually connected in series to form strings, while these strings are connected in parallel to form the solar PV array. Solar panels are made from semiconductors, which are the same class of materials that the electronics inside your mobile phones, laptops, and computers are made of. The most common type of semiconductor used to create solar panels is Silicon, which is the most abundant element in the Earth’s crust. Energy Production 1. Will solar panels produce the same amount of electricity all year long? The energy production of solar panels depends on the amount of irradiance or sunlight that it receives, which changes from month to month. Because of this, solar energy systems won’t produce the same amount of energy every month. The irradiance(and thus, the energy production) is higher during the summer months and lower during the rainy months. 2. What is net metering? With the advent of distributed energy generation like solar energy, everyone can now produce energy right on their very roofs. But since solar energy is an intermittent energy source, we can never exactly control the amount of energy that it produces at any given time. Most of the time, it will produce less or more energy than the amount that we need. And when it produces more energy than what we need at that certain time, the excess energy will automatically go back to the grid. Our electric grid has only been designed for a one-way flow of energy and that direction is from the electric lines to our houses. Our old electric meters, therefore are only capable of reading the amount of energy that is going in this direction. But as we discussed, with solar energy, energy can flow the other way around. This is why with an on-grid solar energy system, we will need to replace our meter with a net meter. A net meter is a type of digital meter that can also read and record the amount of energy that is exported back to the grid or going out of the house. Having a net meter is important for an on-grid system because you will be paid back for a certain amount for every kWh that you export back to the grid. This may sound really good but the problem is that Meralco will only pay you an amount per kWh of exported energy that is equal to the generation charge, which is only around half of the retail price of electricity that you are paying for. Here in the Philippines, the price of electricity is around 10 pesos per kWh while you will be paid only around 5 pesos per kWh of exported energy. This is why in the design of solar energy systems here in the Philippines, we tend to avoid having a system size that would export too much energy back to the grid to minimize the ROI. What we do is we analyze your hourly consumption and determine the optimal system size where you export the least amount of energy back to the grid but still save the maximum amount from your monthly electric bills. Take note that this involves an hourly computation of the solar energy system’s production and your consumption for the whole year, which not all solar companies can do. With Andal Solar, however, we have our own way of doing just that, which means that you are assured that your solar energy system will be just right for your consumption and that you would get the optimum return for your investment. 3. Will my solar panels generate electricity during cloudy or rainy days? What about at night? Solar panels will still generate electricity during cloudy or rainy days, although to a much lesser degree. For off-grid systems, this may be a problem because it means that you will only have a small amount of energy available throughout the day and your batteries will not be charged enough for your nighttime consumption. For on-grid systems, again, this is not a problem because you can always get energy from the utility grid whenever it is not producing as much energy and you need more. This is also automatically managed by the inverter and you would not need anymore to press any switch or do anything to the whole system. In short, you should basically not need to worry whether it is sunny, cloudy, or rainy outside because your solar energy system will still produce energy and can operate by itself without any need for intervention. 4. Is solar energy reliable and powerful enough for my home or business? One of the most common questions about solar energy systems is that if it will be powerful enough to run all of the appliances on your home, which may include several air-conditioners. With off-grid systems, this is a major design consideration because you will only have your off-grid system as your electricity source. For houses that use large air-conditioners, the inverter and batteries in your system might even need to be oversized to accommodate these, which will increase the cost even more. For on-grid systems, however, this is not a problem because you are still connected to the electric grid and will always have this as a backup. In the case where your on-grid solar energy system can’t supply for all of your electricity consumption, the deficit will be taken from the electric grid. During night time, the electric grid will then supply for all of your consumption, similar to when you still don’t have a solar energy system installed. Financials 1. Will solar pay for itself? The good thing about investing in a solar energy system is that it will pay for itself in a relatively low amount of time. Common ROI values for residential solar installations are 5-7 years, depending on many factors like your consumption, system size, cost, and the quality of the system. The lifetime of the system, however, is 25-30 years Be careful, however, when looking at proposals from solar companies and try to ask how they have come up with the value of ROI for your solar energy system. ROI values in solar proposals can be exaggerated to more easily convince you to push forward with the installation. Since having a solar energy system requires a big investment, it is just right for you to make sure that you get accurate and correct information about it. 2. How Much Does a Solar Energy System Cost? Solar energy systems require a large upfront investment but the good thing about it is that it pays for itself through the savings that you get from your monthly electric bills. Typically, the ROI for solar installations range from 5 to 7 years, while it is expected to last for 25 to 30 years. 3. Will solar panels raise my home or business’ property value? At the end of a solar energy system’s lifetime, the expected total monthly savings that the home or business owner will have accumulated would be many, many times more than your initial investment to have it installed. This means that it gives a lot of value to the home or business owner and will definitely lead to an increased price of any property. In fact, in the US, homes with solar panels are selling up to 4% more, which translates to an additional $9,274 on the price of the property, according to Zillow, which is a real estate listing website. Also, they found out that more than 80% of homebuyers say that energy-efficient or energy-saving features in houses are important for them, which makes houses with a solar energy system more in-demand. 4. How soon will I notice a difference in my electricity bills after switching to solar energy? Right after installation, your solar energy system will already be able to produce energy. However, you may still not have a net meter installed at that time from Meralco. Without a net meter, your old meter will not be able to distinguish from the energy that you buy from the grid and the excess energy from your solar energy system that you export it. Your energy exports will then be read as your consumption. This increases your electric bill and reduces the amount of savings that you will be able to see on it. 5. How much will I really save on my electricity bills every month? The amount of savings that you would get from your monthly electric bills depend on the size of your solar energy system and your consumption. This is a graph of a typical hourly residential energy consumption(black curve) and the hourly energy production of a smaller and a larger solar energy system(orange curves). The part of the graph that is shaded in yellow is the energy from your solar energy system that you are able to use for your home’s consumption. In technical terms, this is what we call self-consumption. All of this energy directly translates to savings since instead of buying energy from the electric grid for your consumption, you will get the energy that you need from your solar energy system instead. The part of the graph that is shaded in blue is the excess energy from your solar energy system. Since you will be paid only around half of the retail price of electricity for this, you can view this part of the graph as being only half as valuable as the part that is shaded in yellow. If we increase the size of our solar energy system, its production will become the larger orange curve on the graph. Our self-consumption will increase by a small amount, which is the part of the graph that is shaded in green. Our excess energy, however, will increase by a larger amount, which is the part that is shaded in cyan. This will translate to more savings but the ROI will be longer since you have more excess energy that will only be half as valuable. If you are planning to have a solar energy system installed on your home, it is best to get quotations for different system sizes for you to be able to compare their costs, resulting monthly savings and the ROI for each size. 6. How will switching to solar energy help me budget better? By having a solar energy system, you can save from your monthly electric bills for 25 to 30 years. These monthly savings can help you allocate more of your funds to other more essential expenses, which will in turn, help you budget better. Also, very sudden electricity rate hikes will hurt much less for you because you will be buying less energy from the electric grid. Take note that since our country’s main energy source is coal, the price of our electricity matches the price of coal, which is very volatile. Installation 1. What is the best option for installing solar panels with my budget? If you have a tight budget for solar, it is best to inform your solar company about it so that they can determine the best size of the system that will give you the maximum amount of savings for your budget. Since we at Andal Solar are using microinverter for our installations, you can even opt for a smaller system size now and then just increase it to the optimum size for your consumption when you can already afford it. This is because solar energy systems that use microinverters are modular, which means that increasing the size of your system will just mean installing more solar panels and microinverters on your roof. 2. Will installing solar panels damage my roof? In installing solar panels, installers need to make some penetrations through the roof to securely attach to the purlins underneath. But you do not have to worry because solar mounting manufacturers designed their mounting systems to minimize the risks of leaks. Specifically, their roof attachments have an EPDM rubber with it to prevent the possibility of water leaking into the roof. EPDM rubber is used because it is extremely temperature resistant as it can resist temperatures as high as 150oC and is also extremely durable. Additionally, solar installers can also apply a waterproof sealant on their points of penetration to further minimize the risk of water leakage. In terms of damage to the roof, the surprising thing is that solar panels can even act as a protection to the portion of your roof that is covered by them. Your roof will not be anymore directly exposed to the sun and rain and lastly, solar panels on a roof also cause a cooling effect on the part of the roof that it covers. All in all, instead of damaging your roof, solar panels actually protect your roof instead. 3. How long do solar panels take to install? Do you have to rewire my house? Solar panel installations actually only take a short amount of time, especially for residential systems. It can take only 2-5 days, depending on the system size. After installation, one day will be allotted just for system testing to make sure that everything works perfectly and avoid troubles in the long run. Solar energy systems only need to tap into your main panelboard, which means that your house doesn’t need to be rewired. This will be the only part of your house that will be touched or altered by solar installers and the rest of your house’s wiring will be left untouched. 4. How will I know if my property is a good candidate for solar panels? One thing that you can do to know if your house(or specifically, your roof) is good for solar panels is to look at it from the satellite view of Google Earth. You can easily do this now just through your internet browser and without needing to install anything. Go to the Google Earth website by clicking here. Click on launch Google Earth and then type your address. Most of the time, Google Earth may not be able to immediately locate your house’s exact location. When this happens, try to search for a popular landmark or establishment that is near your house instead and use its location to manually find your house. Once you are already able to see your house, see if any of your roof segments are at an optimum orientation. In the Philippines(and other countries in the Northern Hemisphere), the optimum orientation is due south. Click on the compass icon on the lower right corner of the screen to fix the upwards direction as North and downwards as South. Look at your roof segments and identify the one that is closest to facing South or downward on your screen. This would be the optimum roof to install solar panels on. Lastly, an optimum roof for a solar panel installation does not have any nearby poles, antennas, or any other structure that can cause shading. If your roof is near any such structure, it may significantly reduce the energy production of the solar panels that will be installed there. The best-case scenario is a roof that is clear of any obstructions. 5. What size of solar energy system should I get? The size of the solar energy system that you should have on your home depends on your budget, your hourly electrical consumption, particularly during daytime, and your roof. It would be best to instead ask a solar company about this as they are the ones that can make all the required calculations. Also, make sure to get a quotation for different system sizes for you to choose the best one for you. 6. Do I need to replace my roof before installing solar? It depends on the quality of your roof. If you think that your roof can still last for more than 25 or more years without needing to be repaired or replaced, then you don’t need to replace it first before installation. However, if your roof is already in a not so good condition and may need to be replaced in a few years, it is best to have your roof replaced first because it would be very hard to do so once the solar panels are already installed. 7. What happens during the solar installation process? Since solar panel installations are done on the roof, it would not be much of a hassle for you and affect your day to day activities that much. You will need to give the solar installers access to the inside your home as they will need to make the connection to your main panel board. They may also need to turn off your main electrical supply for a short amount of time to do this. Lastly, depending on the type of inverter that will be installed, you may also need to give the solar installers access to your wifi network for them to connect the inverter to it and set up data monitoring. 8. How much roof space will I need for a solar energy system? The amount of roof space that you will need for solar panels depends on the system size that will be installed. A 1kW solar energy system will usually have 4 solar panels, each having an area of 1.6m2 for a total of 6.4m2. To really be sure if you have enough roof space for solar panels, it is best to consult with a solar company and giving them your address. Through Google Earth, they will be able to estimate how many solar panels they can fit into your roof. However, a site visit would be necessary to really confirm this because there may be some obstructions or other aspects of your roof that can not be seen on Google Earth. For solar energy systems that use string inverters, you will need to reserve a small wall space near your main panel board to mount the string inverter. On the other hand, for microinverters, like the one we install in Andal Solar, this is not anymore necessary because they are just installed on the roof, under the solar panels. 9. Can I install solar panels on my property myself? You can certainly install a solar energy system yourself because it is a pretty simple system, however, you must remember that it will stay on your house for at least 25 years while producing high amounts of voltage and power. This presents a lot of risks especially in terms of causing a fire when improperly designed and installed. Also, without the knowledge of a real solar PV engineer, you would not know the best type of solar panels and inverters to use, the right size that would be perfect for your consumption, on which roof it is best to install the solar panels on and many more. You would not have the best system in terms of design and quality, which also means that you would not get the most out of your investment. Having a solar energy system installed by a legitimate solar company may be more expensive than installing it yourself, but the benefits that you will gain will certainly outweigh the amount that you will save by installing it yourself. And since solar energy systems last for 25 to 30 years, it is very important for it to be composed of high-quality materials and installed at par with the proper quality standards. 10. What should I do now if I want to increase my system size later? For string inverter systems, there is virtually no way to simply increase your system size other than installing another separate system. Aside from installing more solar panels and inverters, you will need to have another set of wiring, switches, and monitoring system. On the other hand, for microinverter systems, like what we install here in Andal Solar, increasing the system size is far easier and will just be about installing more solar panels and microinverters. Operations and Maintenance 1. How much will solar panel maintenance cost? Solar energy systems have no moving parts which make maintaining them virtually cost-free. In fact, the most that you need to do in doing this is washing the solar panels with water. Aside from this, you would just need to make sure that all the wires are still in perfect condition. With the proper knowledge and training, you can easily do this yourself without the help of a professional. 2. Are solar panels difficult to operate and maintain? Solar energy systems are meant to operate by itself without needing any intervention from the homeowner. It doesn’t require you to turn it on in the morning and off in the evening because the system automatically turns on and off depending if the solar panels are producing energy or not. The inverter is also already managing the system by itself, which makes the system’s day to day operation really autonomous. One of the advantages of solar energy among all other energy sources is that it has no moving parts, which translates to easier maintenance for solar energy systems. In fact, maintaining a solar energy system usually just means taking a look at the wires and making sure that everything is nice and tight and maybe washing the solar panels with water once a year. You can even monitor your solar energy system’s energy production remotely through the internet, which makes it really hassle-free to have one on your home. 3. How will I know if a solar energy system is working? Solar energy systems usually have a monitoring system that allows you to monitor the system’s energy production and other system parameters. Depending on the string inverter, this can be in the form of a website and/or a mobile app. String inverters also usually have small LED displays to show data regarding the system’s production. With our microinverter system, you will be able to monitor your system’s energy production through a website and a mobile app. You would also be able to monitor the performance of each solar panel in the system and know which are being shaded by trash or any debris and if they are already dusty. Since this is connected to the internet, you will also be able to monitor your system wherever you are as long as you have an internet connection. 4. Is a solar energy system noisy? Solar energy systems do not have any moving parts within them, which means that they can operate without making any sound. In fact, you would probably not notice having a solar energy system on your home when you have one installed because the system operates quietly on its own without needing you to press any button or operate any switch. Maintenance is also very easy and won’t require much time and energy. This means that having a solar energy system is basically hassle-free and you won’t need to make a large commitment to operating and maintaining it. 5. How do I check my solar energy system’s performance and kW generation? Depending on the brand and type of the inverter, solar energy systems have different ways to monitor performance, energy generation, and all-important system parameters. For string inverters, a straightforward way to monitor the system’s performance is on its built-in LCD display. Since microinverters are installed on the roof, they don’t have something like this, but you would usually still be able to monitor your solar energy system’s production through a mobile app and a website. Here at Andal Solar, we also send monthly and annual performance reports to summarize your system’s performance for you to get the full sense of value that you are getting from your system. 6. Is my solar system covered by a warranty? Here at Andal Solar, we offer a 2-year service warranty that covers workmanship defects and includes monthly and annual performance reports and semi-annual system maintenance and checkups. In terms of the solar panels and inverter, the manufacturers of these usually also give warranties for their products. For solar panels, typical product warranties are as long as 10 years, while also including a 25-year performance warranty. String inverters also come with 5 to 10 years of product warranty. Microinverters, on the other hand, comes with a 10-year warranty, which can also be expanded to 25 years. 7. Do I need to clean my panels? Dust that can accumulate on the solar panels can decrease its energy production which is why you will have to clean it from time to time. However, this effect is not that significant, so 1-2 times of cleaning per year can be enough. For microinverter systems, like what we install in Andal Solar, you can monitor the production of each solar panel on your system. This means that you will be able to know whether one specific solar panel was being shaded, whether because of a piece of debris or plastic that was blown on top of it. This way, you would be able to remove the cause of shading and ensure maximum energy production.
- The Complete Guide on How Solar Panels Produce Energy
Solar energy has become more and more popular these days as a cleaner and cheaper energy source than conventional fossil fuel sources like coal and natural gas. And even though this technology has been around since the 1950s, many are still not familiar with the process of how solar panels can really produce energy. But before we dive into the details, let us first clarify some misconceptions and define our terms. Misconception #1: Solar panels produce electricity from heat. This misconception is very easy to have since from our everyday experience, heat and sunlight always go hand in hand. However, we must first understand that the energy that we get from the sun is in the form of light only. This light is only converted into heat when it hits and is absorbed by objects like our atmosphere, the ground, and our roofs. And as the name suggests, solar energy is the energy from the sun, which is light. Solar panels, therefore, convert sunlight into electricity instead of heat. In fact, similar to electronic devices, they even work better and produce more energy when the ambient temperature is lower, with similar levels of irradiance or sunlight. And since solar panels are not 100% efficient in converting sunlight into electricity, they even produce heat as waste in this process. Misconception #2: The correct name for solar panels is actually solar modules or solar panels. However, for most purposes, they have been used interchangeably, so we will still use the term solar panel/s throughout the rest of the article. Solar cells are the smallest power-generating unit of a solar panel. You may have noticed that some solar panels are made up of small blue or black squares inside. These are solar cells, which produce only a very small voltage of less than 1V. This is why the most common solar panels in the market today have 60 or 72 solar cells inside of them, which are all connected in series to raise the voltage to a usable level. When these solar cells are connected in series, they are placed in a panel, hence, the name solar panel. A solar panel, on the other hand, is a complete, ready to use module that consists of the solar panel, the aluminum frame, the glass, the electric junction box, and the wires. With these misconceptions out of the way, we can start digging into the details of the science of how solar panels produce energy. What Solar Panels are Made Up Of The solar cells are made up of a class of materials called semiconductors. Semiconductors are a class of materials that have an electrical characteristic that is in the middle of that of conductors and insulators. You may be already familiar with conductors and insulators because you encounter them and use objects that are made up of them in your everyday lives. Conductors are basically metals that easily conducts heat and electricity, while insulators are the exact opposite as they do not conduct both heat and electricity very well. The most common type of semiconductor that is used for solar cells is Silicon, mainly because it is the second most abundant element in the Earth’s crust after Oxygen. 90% of the soil, rock, and dust in the Earth’s crust is made up of silicate materials (rock-forming minerals that are made up of Silicon and Oxygen). Semiconductors have also been used to create transistors, which makes up all of the modern electronic devices that we use today. Energy Bands in an Atom To understand why semiconductors have their unique electrical characteristics, we must dive into the physics of it. Remember that an atom is composed of the nucleus, which is composed of protons and neutrons and the electrons which are located in shells that are centered in the nucleus. Depending on the total number of electrons in the atom, it can have multiple larger and larger shells. What’s important here is that the farther an electron is to the nucleus, the higher its energy state. The outermost shell in an atom is called the valence shell. It is also the farthest shell from the nucleus, which means that the electrons in it(called valence electrons) also have the highest energy levels. The different levels of energy that the electrons can have while in this shell are spread out in an energy band which is called the valence band. For a material to conduct electricity, a valence electron must receive some amount of energy for its energy level to be higher than the valence band. When this happens, that electron can now freely move away from the atom and flow as electricity. Its current energy level is now in the conduction band and it is said to have “jumped” from the valence band to the conduction band. For conductors, the conduction band and the valence band overlap with each other, which means that all of their outer electrons already have enough energy to freely move around the whole material. These electrons are called free electrons and this is the reason why this type of material can easily conduct electricity. For both semiconductors and insulators, there is a certain gap(called the band gap) to their valence and conduction bands which represents the amount of energy that must be added to the valence electron for it to be free. The band gap is very large for insulators and this makes it also very hard for an electron to gain enough energy and jump to the conduction band. Valence electrons usually get additional energy from heat. For semiconductors, this is sufficient to have a few valence electrons to jump into the conduction band but for insulators, the band gap is so large that it makes this virtually impossible through heat alone. For semiconductors in absolute zero, the valence electrons get no more additional heat from energy, and they also act like insulators. Doping The great thing about semiconductors is that you can significantly alter and control its characteristics through a process that is called doping. This is done by introducing certain atoms as impurities into a pure semiconductor. When this happens, the semiconductor’s electrical, optical, and even structural properties can be altered. A doped semiconductor is referred to as an extrinsic semiconductor, while a pure semiconductor is called an intrinsic semiconductor. There are two types of extrinsic semiconductors, n-type and p-type semiconductors. The resulting type from doping depends on the impurity that is added. Phosphorus (P) or Arsenic (As) is used to create n-type semiconductors while Boron is used to create p-type semiconductors. The valence band of Phosphorus and Arsenic is very close to the semiconductor’s conduction band which makes it very easy for their valence electrons to jump to the conduction band. When this happens, the conductivity of the whole material is increased. On the other hand, the valence band of Boron is very close to the semiconductor’s valence band. This then makes it very easy for the semiconductor’s valence electrons to jump here. An empty space is left behind on the semiconductor’s valence band, which is called a hole and the conductivity of the whole material is also increased. The Diode An amazing thing happens when you put together an n-type and a p-type semiconductor. First, remember that an n-type semiconductor has gotten extra electrons in its conduction band from doping while a p-type semiconductor got empty spaces or holes in its valence band. When these two materials meet, the extra electrons on their point of contact release some energy and move to the holes, creating a portion that is devoid of free electrons where the two materials meet. This portion is called the depletion region because it has been “depleted” of free electrons. Since this is the case, the free electrons from the n-type side will need a certain voltage called the voltage to pass through the depletion region and travel to the p-type side. Because of this voltage barrier, it becomes hard for the electrons to pass through the depletion region and the whole diode. The resulting material is called a diode. This device is used as an electronic switch that can be turned on and off depending on the polarity and amount of applied voltage. It is very important to discuss diodes here because solar cells are basically just diodes that are designed to use the energy from sunlight to create more free electrons inside of it and generate an electric current. To illustrate this, imagine that a positive voltage is applied to the p-type side of a diode and a negative voltage is applied to the n-type side. The electrons on the p-type side of the depletion region get attracted to the positive terminal, which causes them to move toward it. These electrons then leave behind a hole, which restores the holes on the p-type side of the depletion region. On the other hand, the free electrons on the n-type side get repelled by the negative terminal, pushing them on the n-type side of the depletion region and restoring the free electrons in that area. The result is that the depletion region gets smaller and along with this, the voltage barrier also decreases. Electric current can then flow freely through the diode. In this case, the diode is said to be forward-biased, which is its on-state. Let us now examine what will happen if we will reverse the voltage on the diode. This time, the positive voltage is now connected to the n-type side of the diode and the negative voltage is applied to the p-type side. This time, the free electrons on the n-type side of the diode are attracted to the positive voltage. These electrons then flow through the negative side of the voltage to the p-type side of the diode, filling up the holes near the depletion region. The result is that the depletion region gets bigger, increasing the voltage barrier even more and making it even harder for free electrons to flow through the diode. The diode is now said to be reverse-biased. This is the off-state of the diode. The Diode’s IV Curve These characteristics can easily be summarized and memorized through the use of the diode’s IV curve. The x-axis here corresponds to the voltage across the diode, with reference to its forward bias. This means that the positive voltages refer to a forward bias on the diode while the negative voltages refer to a negative bias. The y-axis then refers to the resulting electric current. As we increase the voltage from 0 as the diode is forward-biased, we can see that the current grows very slowly. But when we hit the voltage at the “knee” of the curve, the current then starts growing exponentially. For silicon diodes, this voltage is called the knee voltage. To “turn on” a diode, you must apply a voltage that is greater than this knee voltage first before a significant amount of current flows in your circuit. Take note here that if a diode is forward biased, it consumes an amount of energy that is equal to the electric current through it times the voltage across the diode, which is just approximately equal to the knee voltage. When we instead apply an increasing voltage while the diode is reverse-biased, the reverse happens. The current quickly increases(although to a much smaller value) to a value that is called the reverse saturation current and stays on that level. You may be wondering how can there still be current in the reverse-biased diode when we have just discussed that in this case, the depletion region widens, which makes it very hard for electrons to pass through. This is a very valid question and one that is rarely addressed in electronics textbooks and online resources. Quantum Tunneling This is due to a phenomenon in quantum mechanics that is called quantum tunneling. In quantum mechanics, particles such as electrons are described to behave very differently in the sense that we are always not certain about their position. Quantum mechanics instead describes their position in terms of probability waves, which are spread around the “apparent” position of the electron and decreases with distance. To understand quantum tunneling, we should analyze an electron in a potential well. Take note that the rectangles on the left and right of the electron in this diagram refer to an energy level that the electron must first have before it can get out of the potential well. We can make the analogy on a rock that is stuck on a real well but we should analyze it in terms of energy. Since the rock is at the bottom of the well, it has a low gravitational potential energy. For the rock to get out of the well, someone must pick it up and carry it to the top, giving it potential energy in the process. If the rock is carried only up to halfway up the well or you give it an insufficient amount of gravitational potential energy, it would just lose it all and fall back down again. This is the exact same case with the electron in a potential well; the only difference is that in the potential well, we are now talking about the electrical potential energy of the electron. According to quantum mechanics, the electron still has a small chance of getting out of the potential well, even if it does not have the required energy level because of quantum tunneling. This is because, as we have discussed, we are uncertain of the position of the electron. For example, if you put an electron in a small box, it may still suddenly appear out of the box if its probability wave reaches out of the box. In the same way, the electron’s probability wave in the potential well may extend outside, which can cause it to “tunnel” through the potential well and get outside of it. Electrons in the depletion layer of a diode can be considered as also being in a potential well because they must also have a sufficient amount of energy to be able to escape. However, because of quantum tunneling, some electrons do escape and flow outside as current. This is what constitutes the reverse saturation current of the diode. Reverse-biased Region and its Similarities to the Solar Cell The reverse-biased region of the IV curve is one that is most important to us because solar cells also operate in this region. To prove this, we must look at how the IV curve changes with increases in the temperature of the diode. When the diode becomes hotter, the valence electrons in the semiconductor material gain additional energy, which allows some of them to jump to the conduction band and become free electrons. This means that the current must increase. However, in the forward-biased region, we don’t see such an increase because the number of additional free electrons that the heat generates is very low compared to the total number of free electrons that are already in the material. Meanwhile, in the reverse-biased region, there are almost no free electrons, so the number of additional free electrons that are generated by heat is very large in comparison to the already existing ones. It is important to notice that the reverse saturation current is proportional to temperature, which means that, for example, if you double the diode’s temperature, the reverse saturation current will also double its value. The same thing happens when the additional free electrons get their energy from sunlight instead of heat. And because there are now many more free electrons in the depletion region, more electrons can now tunnel through it and be channeled and used as an electric current. Therefore, a solar cell is just a diode that is operating in the reverse-biased region, with the only difference being that the solar cell itself is now the one that is producing energy instead of an outside voltage source. With this knowledge, we will also be able to learn the characteristics of solar cells and thus, solar panels: Similar to a diode, the solar cell can only produce certain pairs of values for its voltage and current and these values are graphed in an IV curve. In the same way that the reverse saturation current is the maximum reverse current that we can have on the diode, the solar cell also has a maximum amount of current that it can produce, which is called the short-circuit current. · If the diode is forward-biased, it consumes energy, but when it is reverse-biased, it instead generates a small amount of energy from heat. On the other hand, a solar cell also generates energy while operating in the reverse biased region. It then consumes energy instead when the current flows in the opposite direction. When this happens, the solar cell may be damaged since they are not designed to consume energy themselves. This is the reason why solar panels still need string fuses even though its wires are already capable of handling even its short-circuit current. String fuses prevent an excess amount of current from the other strings in the PV array to go to one faulty string, causing the solar panels in this string to consume all the energy produced and damage them. · In the same way that the reverse saturation current is proportional to heat, the current that is produced by a solar cell is also proportional to the received irradiance or energy from sunlight. The Photoelectric Effect and the First Solar Cell The whole phenomenon of objects generating electricity when hit by light is called the photoelectric effect, which was first discovered in 1887 by the German physicist named Heinrich Rudolf Hertz. Hertz was more famous for his work on radio waves and his discovery of the photoelectric effect actually happened while experimenting on different electromagnetic waves. He noticed that when he shined ultraviolet light(which is also a form of electromagnetic wave, along with all frequencies of light) on the two metal electrodes of a voltage source, the voltage level can be increased to a point that it can cause sparking. It was only until 1902, however, when an explanation of why this happens was proposed by another German physicist named Philipp Lenard. Lenard proposed that electrically charged particles must be dislodged from the metal surface when it is illuminated. Although Lenard was right, still, nobody understood how this happens. The theory of electromagnetism by James Maxwell was already available at that time, but it was still not enough to explain it. In fact, it even contradicts the predictions of the electromagnetic theory. When scientists tried to measure the kinetic energy of the electrons that were released due to the photoelectric effect, they find out that it does not vary with the intensity of the light, which is what is predicted by electromagnetic theory. What they found out was that kinetic energies were instead proportional to the frequency of the light. The only effect that light intensity had was to increase the number of electrons that were released. In 1905, Albert Einstein concluded that light should be made up of particles that were called photons, which contain a fixed amount of energy that is proportional to the light’s frequency. At that time, this is a very bold conclusion to make since the electromagnetic theory has seemed to end the debate on whether light is a particle or a wave by explaining that light is a form of electromagnetic wave. With the assumption of light being made up of photons, Einstein was able to lay out the math that explains how the photoelectric effect works. But even if this is the case, it was already universally-accepted in the scientific community that light is a form of a wave. Because of this, Einstein’s work on the photoelectric effect was still doubted by many scientists at that time. However, in 1916, the American physicist named Robert Millikan was able to verify Einstein’s mathematical model of the photoelectric effect, which caused Einstein to be awarded a Nobel Prize in Physics in 1921. More than three decades from then, Einstein’s mathematical model of the photoelectric effect was first put to practical use with the invention of the first solar cell. Gerald Pearson, Calvin Fuller, and Darly Chaplin worked together at Bell Labs and was able to develop the first silicon solar cell in 1954. Modularity of Solar Energy Now we know the basic building blocks of solar energy, which is the solar cell and how it works, we can immediately see and understand from this one of the advantages of solar energy compared to all the other energy sources, and that is modularity. Modularity refers to the use of individually distinct functional units and that is exactly how solar energy can easily be scaled up to meet any requirement. For example, individual solar cells can power calculators that require only a little amount of power. Garden lights that require a little more power than that can be powered by a small solar panel. Going larger, street lights can also be powered by solar panels that are just a little bit smaller than the solar panels that are most commonly used. To power a residential home or even a large commercial building, you will just need to install the right number of solar panels on their roofs. Lastly, in the extreme case, if you want to have a specific size of a solar power plant, you will then just use more solar panels to reach your requirement. This characteristic of solar energy is very unique to it and can never be found on any other energy source. All of the other energy sources require them to be produced in large power plants only, without an option to go smaller and meet smaller energy demands. This makes solar energy very versatile, allowing it to be used in almost any application, from solar-powered calculators to satellites. Building Solar Panels from Solar Cells As we have mentioned, solar cells produce only a very low amount of voltage (less than 1V) although they can already produce a decent amount of current. This is a problem because you will not be able to use it to power anything. For example, no matter how large your 12V battery is, you will still not be able to use it to power a machine that needs 24V. To overcome this problem, solar cells are connected in series in a solar panel to increase the total voltage to a useable level. The most commonly used number of cells in series in solar panels are 60 and 72. If you think about it, 60 or 72 cells in one solar panel can also be arranged in two strings of 30 and 36 solar cells, respectively. But this is never done in actual solar panel designs. The reason for this, however, is not just to reach a higher voltage. The more number of strings that you have, the higher the total current of the solar panel will be. This is why having more strings of solar cells in a solar panel is not advisable as this will incur more losses in the form of heat. In fact, the amount of energy that is lost due to heat is proportional to the square of the current. This means that if you double the number of strings(and thus, the current), the total energy lost to heat will be quadrupled. Conversely, if you reduce the number of strings by half, the total energy lost will be decreased by one-fourth. Efficiency in a solar panel is very important because more efficiency will mean more produced energy for the same amount of area. And in the very competitive solar panel market today, even just a 1% difference in efficiency can already translate to many more sales and projects. The Solar Panel’s IV Curve We have already discussed the solar panel’s IV curve, but it is very important to look at it more deeply as this will also give us an idea of how solar panels work in actual solar installations. As we have already discussed, this is what a solar panel’s IV curve looks like: There are four important points on the IV curve that are always shown on any solar panel’s datasheet: Open-Circuit Voltage – this is the maximum voltage that a solar panel can produce and is also the point where it produces no current. Since power is just the product of the voltage and current, the power produced at this point is 0. This point of the solar panel’s IV curve is the safest and is usually considered as the point where the solar panel is “off”. However, take note that the best way to turn off a solar panel is to cover it. In fact, solar panel manufacturers don’t even recommend disconnecting a solar panel while under the sun as this can cause arcing and fires. For solar PV engineers, the open-circuit voltage is used to calculate the maximum number of solar panels that can be put on one string. Short-Circuit Voltage – this is the maximum current that a solar panel can produce and is also the point where it produces no voltage. Similar to the open-circuit voltage, the solar panel also produces no power at this point. However, short-circuiting a solar panel to turn it off is not advisable because it will still produce some amount of heat on its wires. But since the wires built-in the solar panels are already designed to withstand its short-circuit current, this is still a relatively safe way to turn it off. Voltage and Current at MPP – if we study all the points in the IV curve closely, we will notice that the solar panel will produce the maximum amount of power if it operates on one specific point, which is called the maximum power point. The voltage and current at this point are called maximum power voltage and maximum power current, respectively. During operation, we would want the solar panel to always operate on this point to produce the most amount of power. To achieve this, inverters are designed to have a Maximum Power Point Tracking(MPPT) Function that forces the solar panel to operate on its maximum power point(MPP). Since the solar panel produces the most amount of power at its MPP, it also reaches its maximum efficiency when operating at this point. Changes in the IV Curve In its operation, a solar panel’s IV curve will change, depending on the available irradiance and the temperature of its solar cells. As we have discussed, a solar panel’s current is proportional to the irradiance, as can also be seen on the graph of the different IV curves for different values of irradiance. The IV curve also changes with respect to the solar cell’s temperature. As we have discussed, its effect on the total current is negligible, but for the voltage, its effect is huge and must be taken into consideration in designing solar PV arrays. The changes in the solar panel’s voltage are inversely proportional to temperature, which means that lower solar cell temperatures will lead to higher voltages. In the design of solar PV arrays, it is important to note the lowest expected temperature in the area to determine the lowest expected solar cell temperature and thus, the highest voltage that it can produce. This is done so that we are sure that the voltage produced by the solar PV array will never exceed the inverter’s input voltage at any time and day throughout the year. We can predict the effect of changes in temperature to the IV curve through the use of three temperature coefficients which can be seen on a solar panel’s datasheet. These are the temperature coefficients of current, voltage, and power. If you will take a look at these values on a solar panel’s datasheet, you will see that the temperature coefficient for current is a positive number, while the temperature coefficients for voltage and power are both negative. This matches what we have discussed earlier that increases in solar cell temperature increase the total current by a very small amount and that the voltage increases with lower solar cell temperatures. What we haven’t discussed yet, however, is how the solar panel’s output power is affected by changes in the solar cell’s temperature. As we can see on the datasheet, the temperature coefficient of power is negative, which means that it actually increases as the solar cell’s temperature decreases. This means that solar panels would actually produce more power during cool, sunny days than during sunny but scorching hot days. STC and NOCT Another thing that needs to be discussed that is also related to the changes in the IV curve is the difference between STC and NOCT. STC stands for standard test conditions, which corresponds to the ideal input of 1,000W/m2 and a solar cell temperature of 25 degrees Celcius. The solar panel’s rated maximum power is defined as the power that the solar panel will produce during these conditions. However, take note that these are ideal conditions and are rarely met in actual operation. Actual operating conditions are more accurately represented by NOCT, which corresponds to an irradiance of 800W/m2 and a solar cell temperature of 45 degrees Celsius. Effect of Shading Even though solar panels can be installed virtually anywhere, they are still limited by shading from trees, nearby buildings, electrical posts, and other tall objects. This is a problem because shading can disproportionately affect the power production of a string of solar panels. This is because the solar panels in a string are forced to produce the same amount of current and therefore, any amount of shading that will decrease the output current of one solar panel will also decrease the output current of all solar panels in the string. A good way to think about this is by thinking that all solar panels in a string will only perform as well as the worst-performing solar panel. This problem is even much more worse in the case of severe shading. To understand this, we must first remember that the inverter is actively looking for total voltage and current value for the whole array where the total power will be at its maximum. Now, going back to our case of severe shading, imagine one solar panel in a string that is severely shaded. Also, for this analysis, we will also only consider one string in the solar PV array to make it simple. The IV curve of the severely shaded solar panel will be significantly lower because of the lower input irradiance. The other solar panels can follow this and also significantly reduce their output current and power, but the inverter’s MPPT function will still look for the point where the string will produce the most energy as a whole. In these cases, the MPP of the whole string may happen at a point where the severely shaded solar panel will be forced to operate in the negative voltage side of its IV curve. When this happens, the solar panel will then consume power, instead of producing it. Its power production will be negative, but since the power production of all the other solar panels in the string are not significantly decreased, the total power output of the string, in this case, will still be at its maximum. Since solar panels are composed of several solar cells in series, the same disproportionate effect happens in the level of the solar panel. For example, if one solar panel gets 20% of its area shaded, its power production would drop by much more than 20% for the same reason. Since all the solar cells in a solar panel are connected in series, they would also perform only as good as the worst-performing solar cell. In solar installations, it is a common practice to avoid shading from 9 AM to 3 PM as these are the peak sun hours and is when the solar panel receives most of the irradiance. If shading is still unavoidable, another good solution is to use microinverters instead. In microinverter systems, solar panels connect directly to the microinverter, which means that the solar panels are not anymore connected in series. In fact, each solar panel will even have its own maximum power point tracker, so any form of shading will only affect the shaded solar panel/s. Bypass Diodes To minimize the effects of shading on a solar panel, manufacturers have used what are called bypass diodes to effectively “bypass” a severely shaded solar cell, remove it from the string and not let it affect the production of all the other solar cells and also to protect it from damage. Remember that a severely shaded solar cell can operate in the negative voltage part of its IV curve. When this happens, it will then consume energy instead of producing it and may be damaged in the process. If we put a bypass diode in parallel to it in a way such that a negative voltage from the solar cell will forward bias the diode, that solar cell will then effectively be in parallel with a short circuit. This way, the current from all the other solar panels in the string will choose to flow through the diode instead of the severely shaded solar panel. In reality, however, the cost of adding a bypass diode to each solar cell outweighs the benefits of having them, so what solar panel manufacturers do is they only add 2 or 4 bypass diodes with each one being connected in parallel to one half or one-fourth of the total number of solar cells.
- Our Service Package | Andal Solar
Home Solar Basics Our Energy Industry Why Solar Energy? About Andal Solar Why Andal Solar? Our Service Package Blog Inquiry New Page More Our Service Package OUR CUSTOMERS ARE OUR PARTNERS Here in Andal Solar, we treat our customers as partners since we share the same goal of helping the nation prosper through our solar energy revolution. This company is built more on passion than profit and our customers are our partners in helping our country achieve its fullest potential. Because of this, we are offering our customers a very special service package that will surely make them feel that they are indeed our partners. Our service package includes: Designing and Installation of the solar panels and the whole solar energy system. This includes mounting of the solar panels and microinverters on the roof, installation of all the necessary wiring up to the main distribution panel. Setting up of the EMA (Energy Monitoring and Analysis) System and EMA app on the customer’s mobile phones. Orientation about the EMA and all system parameters shown on it, this includes how to measure system performance using the app and in determining problems in the system and what actions to take if the customer will troubleshoot and repair by themselves after the service warranty. Service warranty of 2 years. This includes continuous system performance monitoring through the EMA, semi-annual system check-up and maintenance, and troubleshooting and repair in case of problems reported by the customer. Preparing all necessary documents and processing for the net metering application. Conducting a seminar on the installed solar energy system for the customer to know everything about their system. This includes the turnover of all system plans/drawings for their reference. Equipment warranty of 10 years for the solar panels, 10 years for the microinverters and 2 years for other system components (wires, conduits, dc, and ac switches, etc.). Teaching the customer how to operate, maintain, troubleshoot and repair the system. Monthly and annual system performance report email during the duration of the service warranty. Free 1 dozen Ferrero bouquet as a sign of our deepest thanks and gratitude. Earn 3% commission through referral of other customers. LET'S TALK! Contact Us Contact Us 0936-442-6935 Send Us An Email 0936-442-6935 Like Us on Facebook Share
- PVComp | Andal Solar
PVComp - Solar PV Simulation Software
- Andal Solar | Solar PV Design & Installation|
High-quality solar installations for you to be able to use solar energy and save up from your monthly electric bills. Know More Home Solar Basics Our Energy Industry Why Solar Energy? About Andal Solar Why Andal Solar? Our Service Package Blog Inquiry New Page More Our Services Sizing and Design We use the best engineering practices regarding solar sizing and design to ensure that the best type and right size of system will be installed for the customer. Installation Our solar installations follow the industry standards and guidelines to ensure that every component is properly installed and would last for more than 25 years. Customer Education We make sure that our customers truly understand how their solar energy system works and how to operate, monitor, analyze and maintain the whole system by themselves Our Blogs Our Mission Towards a Solar-Powered Philippines Click on the image to know why the Philippines need solar energy! Get In Touch Submit Thanks for submitting! Contact Us 0936-442-6935 Send Us An Email firstname.lastname@example.org Like Us on Facebook Share