How does solar inverter work?

Solar inverters are the part of your photovoltaic system that converts the direct current from your photovoltaic panels into the alternating current that your home uses. They’re tucked away and less prominent than solar panels, but they’re just as important to the operation of your system, so it’s worth taking the time to understand the different types and tradeoffs so you can make the right choice. Lower cost does come with some drawbacks, however. String inverters suffer from a problem where a power drop in one panel causes power to drop across the entire string. (In a way, this is similar to how a single broken bulb can cause a whole strand of Christmas lights to go dark.) A power drop could be caused by shadows from any number of things: a chimney, nearby buildings, trees, leaves, soiling from dirt or birds. Or, it could also be caused by a faulty panel. Most solar arrays will experience shading for at least some parts of the day, so with a string inverter you’ll likely experience reduced power collection compared with other inverter types. Some string inverters manage this problem better than others. An inverter has a unit called a Maximum Power Point Tracker (MPPT) that handles the output from a string of panels. Some have inverters have more than one MPPT, each of which can individually optimize the power output of a string. So, if your inverter has two or more MPPT units, your solar array can be wired into multiple strings and the inverter can manage each one individually. This means that if your inverter has two MPPT units, and one of your strings gets some shade during the day, the other string won’t be affected. Another downside of string inverters is the inability to monitor the performance of individual panels in the system. This means that if you lose power in the array, you won’t know if it’s a single faulty panel or a more system-wide issue. Finally, a string inverter is a single point of failure. A ten year warranty is typical, but a failure after that could mean an expensive replacement. This also places a limit on future expansion. For example, if you decide in the future to buy an electric car and want to add more panels to charge it with, you will be limited by the capacity of the inverter, and might be forced to upgrade or add another inverter. Keep in mind that these drawbacks may not be severe enough to warrant the higher cost of a more sophisticated inverter system. It’s true that a string inverter may not harvest as much electricity as a more expensive option, but you’ll need to consider whether the value of that extra electricity you’d gain over the lifetime of the system would be greater than the added cost.