Residential solar power systems are made up of two main components:
Panels (sometimes called modules) and
Inverters
While we could spend all day talking about panels and how magical they are, the purpose of this article is to explain what an inverter does and the different types of inverters that exist.
What does an inverter do?
The solar panels on your roof generate power. That power is generated as Direct Current (DC). However, almost all your home appliances, including your lights, fridge, outlets, TV, and more, use Alternating Current (AC).
At its core, an inverter takes the DC current and changes it into AC current so you can actually use the energy generated by the solar panels.
Over the last decade or two, inverter technology has advanced quickly and inverters have become much smarter. Smart inverters come with built-in charge controllers, data monitoring systems, and the ability to efficiently and safely tie into the existing power grid, among other things. In many ways, the inverter is the central and most important part of your solar system.
These new inverter features allow for local net metering programs as well as smart home integrations.
Before you buy a shiny new set of solar panels, you should know there are three types of inverters
String
Micro
DC Optimizers
String Inverters
String inverters (sometimes called single or central inverters) run the panels in series. Running in series means that each one runs power from one panel to the next. Think of lights on a Christmas Tree. If one bulb goes out, a whole section dies. That’s because they are run in series. String inverters can be used with any panel brand.
String Inverter – Pros
Traditionally, string inverters have been cheaper.
String inverters can be easier to install because they accept DC input from multiple panels and do not need to be installed directly adjacent to individual panels. This also makes them somewhat easier to maintain, though possibly more difficult to troubleshoot if something goes wrong.
String Inverters – Cons
Because string inverters treat a group of panels as if it were a single large panel, any problems with one panel are felt across the entire string. For example, if shading over one or two panels causes poor performance, the rest of the panels suffer an equivalent output loss.
Large inverters can take up space on the side of your house or garage.
They typically carry a 10-15 year warranty. If the inverter goes out, the whole system is dead.
If you add to your system in the future, you may have to add an additional string inverter, which can increase your cost of adding on to more than just extra panels.
You must install a minimum of 8 panels, otherwise, you would have to use a microinverter.
Microinverters
Microinverters run in parallel, or independently of each other. This means if one panel or inverter goes down, the rest of the system is still operational. They are small and go on the back of each panel.
Micro Inverters – Pros
Microinverters use something called “power point tracking,” which means if one solar panel is shaded from the sun, the rest of the panels are not impacted.
Microinverters can be easier to fix, because there is typically a single-point-of-failure, unlike string inverters where the problem can be harder to diagnose.
They carry a 25-year warranty and allow us to monitor the system panel by panel instead of just seeing the system as a whole.
You can place one panel per roof, allowing more flexibility in system design and layout. It's easier to add more panels in the future, one at a time if you wanted.
Micro inverted systems generally produce around 12% more power than single inverted systems.
Micro Inverters – Cons
Microinverters traditionally cost more than string inverters, though this is changing.
Microinverters can be more complex and costly to install because they must be installed in tandem with individual solar panels.
They also have a higher failure rate than single inverters.
DC Optimizers
SolarEdge, which has gained a huge portion of the residential solar market, offers a string inverter that also has DC optimizers attached to each panel. These DC optimizers work similarly to micro inverters, helping the panel produce as much power as it can, even in shaded environments. Then collectively, the power is run in series back to the string inverter.
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