Solar panels collect sunlight. But how does that sunlight turn into electricity?
This is where the essential part of a residential solar system comes into play: a solar inverter. A solar inverter takes the electricity your solar panels make and turns it into electricity the devices in your home can use.
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.
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. Going into your inverter shopping experience armed with information will ensure you’re getting the best deal available.
Here’s what you need to know.
What is a solar inverter and what do they 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.
Types of solar inverters
Inverters come in two types: string inverters and microinverters.
String inverter
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.
If you’re locked in on string inverters, there’s an additional investment you can make that will help bring them up to par with microinverters and prevent you from suffering from a massive dip in production if you have panels that are shaded or damaged. You can pair your string inverter installation with DC power optimizers. These power optimizers are installed individually on the solar panels, like microinverters would be, except they’re a more inexpensive choice. When power optimizers are installed, one solar panel dipping in energy production doesn’t affect the other panels.
Pros and cons of string inverters
Pros
Cons
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Less productive
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Weaker warranties
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, ensuring a higher level of performance across the entirety of your solar panel system.
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.
Pros and cons of microinverters
Pros
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Stronger warranties
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More efficient
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Last longer
Cons
How to choose a solar 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.
Inverter warranties
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
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.
The bottom line
Education is one good guard against falling prey to scammy solar companies. In 2023, supply was a big issue for homeowners looking for solar inverters. There was a decent chance that, if you were looking for solar equipment last year, your preferred picks might not be available. Data analyst firm Wood Mackenzie has released projections that more accessible supply lines will rectify some of these issues in 2024, but America’s energy policy largely hinges on the upcoming presidential election. No matter what, though, make sure you get the best overall deal by comparing multiple quotes from different solar companies.
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.
