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What You Need to Know About Solar Inverters: Essential Solar Equipment

You need an inverter to use electricity from your solar panels. Here's what you need to know when you're shopping.

A solar installer connects a panel to a microinverter
adamkaz/Getty Images

Solar panels are an investment that returns long-term savings, enjoys a generous tax credit from the government and can provide you with reliable clean energy for years. And while solar adoption is on the rise, if you don't know how a solar panel system works, you're likely not alone. Before you shop, though, it's a good idea to brush up on some of the basics: solar panel types, net metering and, maybe, home backup batteries.

Another bit of equipment you should know is the solar inverter, an essential part of a residential solar system. It takes the electricity your solar panels make and turns it into electricity the devices in your home can use. While the solar inverter market is dominated by just a couple of options, knowing how inverters work will help you make sure your system is optimized and fits your needs. Education is one good guard against falling prey to scammy solar companies (which exist, but don't appear to be that common).

If you're thinking about going solar, learn what you need to know before buying, how solar panels deteriorate and how you can find a solar financing option that works for you.

What does an inverter do?

An inverter's main function is changing the electricity from direct current to alternating current. Solar panels generate direct current electricity, which can't be used by the grid. An inverter ensures the power you generate is compatible with the grid by switching it to alternating current.

Inverters today do a lot more, though. They're the bit of equipment that monitors and reports power generation and usage. If a solar panel system offers monitoring online or through an app (it likely will), the inverters are collecting and sharing that information.

Advanced solar inverters can disconnect your home from the grid in case of a power outage. Solar arrays without storage and a capable inverter will shut down when the grid goes down, but with the right technology, you can keep the lights on.

What are the different types of inverter?

Inverters come in two types: string inverters and microinverters.

String inverters are the old guard of solar inverters. They do the direct to alternating current conversion for a group of solar panels (or a string, if you want to stick with the jargon) at one, centralized location. They're the cheapest option and, since they're usually installed somewhere easily accessible (like the side of your house), they'll be easier to service if they need it.

The downside of string inverters is that they're a bit of a blunter tool than their microinverter counterparts. Because they handle whole groups of panels at once, a dip in production in one panel brings down the performance of all the panels. If one of the panels in a string is shaded and produces less power, every panel in the string produces at that lower level. A roof that's partially shaded throughout the day might be better suited to microinverters.

Microinverters perform the same direct current to alternating current switch, but at each individual panel. With microinverters at each panel, the production of panels aren't chained to each other. If one is shaded, another in full sun can keep producing at full-sun levels. Microinverters are more expensive, but better fits for partially shaded or complex roofs where panels face different directions or are set at different angles.

Because microinverters are connected to each panel, servicing them requires a technician getting up on the roof. That means maintenance can be a bit more expensive, though maintenance for solar panel systems is usually fairly minimal. Microinverters typically come with stronger, 25-year warranties, than string inverters, which are typically about 12 years.

A solar panel system might also use a string inverter with power optimizers. Power optimizers don't convert the electricity to alternating current. That still happens in one place at the string inverter. Instead, power optimizers make it possible for panels to produce independently of each other. If one is shaded, the others can carry on. More or less, power optimizers and microinverters accomplish the same job in different ways.

Choosing the best inverter

Once you know whether a string inverter or microinverters are most suitable for your house, you want to make sure you're getting a good product. Within each category, there are a couple of useful points of comparison: warranty and efficiency.

While typical microinverter warranties are twice as long as the typical string inverter warranty, differences exist between products of the same group. A longer warranty might make one inverter a much better choice than another.

Efficiency is a measure of how much energy is lost (usually through heat) as the inverter does its job. Efficiency ratings should be readily available for any inverter on the market. Higher efficiency means less energy lost between the panels and your house.

Like a lot of things in 2022, you might be limited by supply. Supply chain issues have come to the solar industry as well and your preferred equipment might not be available, but it can't hurt to ask. Going in armed with information will ensure you're getting the best deal available.