Solar panels generate DC electricity. DC stands for Direct Current. The electric grid uses AC electricity. AC here stands for Alternative Current. Your inverter converts the DC electricity from your solar panels to AC electricity.
Modern solar panel inverters do a lot more than just convert DC to AC, they also monitor and report on the performance of your solar panels. If you are using an app to monitor the performance of your solar panels, then that information is coming from your inverter.
Another function of inverters is to disconnect your solar panel system from the grid in the event of a power outage. You do not want your panels sending power back into the grid during an outage when you possibly have an engineer working on the line. In this situation your panels will stop powering your home. Advanced inverters can in this situation isolate your system from the grid but allow your panels to keep powering your home.
There are 3 common types of inverters used in solar power systems. They are
- String Inverters
- Micro Inverters
- Hybrid Optimisers
String inverters have been around along time and the technology behind them is well proven. Where they are used panels are arranged in rows or groups. Each of these rows makes up a string of panels. You can connect multiple strings to the inverter.
While string inverters have been around along time and work well, they have one downside. If one of the panels on your string is compromised in some way, say by some shading or damage it affects the performance of the whole string.
Micro inverters are newer than string inverters. They are popular with residential solar installations. Unlike string inverters where there is only one connection from the string of panels to the inverter, micro inverters have each panel connected individually to it.
There are some advantages with this approach. One damaged or compromise panel will only affect its own performance and not the performance of other panels in the system. Also, as all the panels are connected individually it is possible to monitor performance on a solar panel level.
Micro inverters been relatively new technology tend to cost more than string inverters but that extra cost can be offset by better solar panel performance.
If your solar panel system has a battery or you plan to export unused electricity back into the grid you will have what is known as a hybrid inverter. Often this is a string inverter with the additional software and changeover switches required installed.
How powerful does your solar panel inverter need to be
While there are a few factors to take into account when deciding on the size of your inverter, the size of your solar panel system is the most important factor. Because your solar inverter converts DC electricity coming from the array, it needs to have the capacity to handle all the power the array produces.
As a rule of thumb your inverter needs to be as powerful as your system less 10% – 20%. So, if you have a 6kWh system you will need 5kWh inverter