When it comes to residential solar installations, string inverters are the one that is more commonly used because it is the older type of inverter technology and have been in the market longer. Also, the public and most solar installers themselves are not yet too familiar with microinverters because this is a newer type of solar inverter technology.
However, with the development of microinverter technology, it has already caught up with string inverters and has even overtaken them in terms of quality and value for installers and homeowners alike. Here are 8 reasons why microinverters are now better than string inverters for residential solar installations.
The main function of solar inverters is to convert the DC electricity that the solar panels are producing to usable AC electricity. However, they also perform another function which is very important in keeping the efficiency of the solar panels at its maximum, which is called MPPT or Maximum Power Point Tracking.
For microinverters, there is a dedicated MPPT or Maximum Power Point Tracker for each individual solar panel on the whole array, which ensures that each solar panel’s energy production is optimized to its maximum. For string inverters, however, there is usually only one, two or three MPPTs for the whole array, which can only be used instead to optimize strings of solar panels rather than individual solar panels for microinverters.
Minimizes Losses Due to Shading
For string inverters, solar panels are arranged into strings and the solar panels on a single string then work as a single unit in producing energy. The problem with this setup is that when one solar panel is shaded, all the other solar panels on the string also suffer a reduction in their energy production. The result is that the energy production of your whole array is then disproportionately affected by shading in the sense that only a small amount of shading can already severely reduce its energy production.
For microinverters, this is never a problem because each solar panel in the array will be working independently with each other. This means that when one solar panel is shaded, only that solar panel will suffer a loss in its energy output. And since each solar panel has a dedicated MPPT for itself, this loss will be reduced even more to a minimum.
Module Level Monitoring
Since each solar panel in a microinverter system has a dedicated input and MPPT, you will also be able to monitor the individual energy production and performance of each solar panel. With this, you will be able to identify which one/s are performing bad and thus, be able to troubleshoot accordingly.
For example, if you notice that one specific solar panel has not been producing energy very well, it might be caused by a piece of trash or plastic that was blown on top of the solar panel. By being able to monitor each individual solar panel’s production, you will immediately be able to fix these problems.
For string inverters, on the other hand, this is not possible as it is not capable of collecting the individual solar panel’s energy production data. You would only be able to monitor the total energy production of the whole array or the strings in the array, but you would have no idea about each individual solar panel’s performance.
When solar panels are connected together to form strings, the voltages that they produce add up, creating high DC voltages in your roof. For large systems, this can be as high as 1,000V while it can be up to 600V for typical residential homes. These levels of voltages, if not installed properly, can cause arcing, which can then lead to fires.
For microinverter systems, however, solar panels are not anymore connected to form strings and thus, their voltages do not add up anymore. Because of this, the highest voltage in microinverter systems are only the 220V AC on its output side, which is no different and no more dangerous than your house’s electrical system.
Another disadvantage of string inverters is that all of the solar panels on the same string and MPPT input must be installed on roofs with similar tilts and orientation. This is not a problem for buildings with large roof segments, but it is a common problem for residential houses whose roofs are composed of many small segments.
With microinverters, you have more flexibility in terms of which roof segments you want to install solar panels on. You would also be able to utilize your roof area to its maximum potential in terms of solar energy production.
Microinverters have the advantage of being modular in nature, because of their small size. This makes it easier for anyone to achieve any system size by using as many microinverters as they need. Also, increasing your system size long after its installation is also made easier as you will just need to install more solar panels and microinverters as per your requirement.
For string inverters, this won’t be as easy and increasing your system size will mean installing another new and separate system than your existing one.
Microinverters are smaller and have been designed to be installed on the roof, under the solar panels. With this, they can already withstand being exposed in the sun and rain for at least 25 years, which is the same amount of time as the lifetime of solar panels.
String inverters, on the other hand, will need to be mounted on a wall, which is usually close to your main panel board. This means that you will need to dedicate a space on your wall for it, a space that you will not be able to use anymore for at least 25 years.
Has a Longer Lifetime
Microinverters have a rated lifetime of 25 years, which is already similar to the solar panel’s rated lifetime. String inverters, on the other hand, have a rated lifetime of only around 10-15 years. This means that for the total lifetime of your solar panels, you will have to replace your string inverter/s at least once. Another problem with this is that solar installers usually don’t tell this to their clients, so many of them are still not aware about this!