Solar systems are complex and have more components than you might think, and each part is crucial to the success of your system, like an inverter. The efficiency of your solar system relies not only on how powerful your solar panels are, but also on your solar power inverter.
But why do solar cells need an inverter? Many homeowners are unaware that solar panels produce a form of electricity that’s unusable for their homes, which is why an inverter is needed.
Solar cells need to convert the energy harnessed from the sun to a usable type of electricity, a process known as inverting because it’s taking one form of energy and changing it to another.
Modern appliances rely on alternating current (AC) electricity, but electricity from solar panels comes out as direct current (DC) power. The DC power is converted to AC electricity so you can have light when you turn your lamps on and binge your favorite Netflix show on your television.
You might be wondering, “Can a solar panel work without an inverter?” Yes. While most home appliances rely on AC power, some can be powered with DC power, like your cellphone and laptop. If most of your appliances run on DC power, then you don’t have a need for an inverter. If this is the case for you, you would be able to connect your solar panels directly to a DC-to-DC converter, or a charger controller, that produces 12-, 24- or 48-volt DC as its output. This is common with off-grid setups.
There are several solar power inverters for homes currently available on the market, including:
This type is the oldest and most common inverter used today. They connect a string of solar panels to one inverter, like holiday lights. Having been on the market for decades, string inverters are reliable and are the least expensive option. This type of inverter is easily accessed since it is centrally located on the side of the house, allowing you to monitor, repair or replace the inverter with ease. It’s important to think about your solar inverter placement because you want it to be in an area that’s moisture resistant, away from direct sunlight and has proper air ventilation to keep your system working optimally.
While reliable, string inverters aren’t as efficient at optimizing solar energy output. This inverter is connected to a string of solar panels, hence the name, meaning that shade on one solar panel will stop the power output of the rest of the string. Since multiple panels are connected in one string, you are provided with total-system monitoring, which can be a hindrance if you want to be able to diagnose issues with individual solar panels.
Located on the back of each solar panel, power optimizers work with a string inverter to convert DC to AC. They can condition the DC electricity produced by each individual solar power, meaning that if one solar panel is shaded a bit, it won’t diminish the output of the entire string of panels. Power optimizers also have the capability of system-level monitoring and panel-level monitoring because of the string inverter, meaning you can easily diagnose any solar output issues since each solar panel can be monitored individually.
This is a more expensive option and requires additional power optimizers. And if you choose to expand your solar system later you would need to add more string inverters. Since power optimizers are on the backs of the solar panels, it means your access to them is on the roof, which makes it more difficult to repair and replace them if any issues arise.
Microinverters can convert DC to AC directly from the back of each solar panel. This type of solar power inverter for homes doesn’t require a string inverter since each microinverter takes care of the conversion of each panel. If shade covers one of your panels, only that panel will produce less without affecting the output of the rest of the panels. They also allow for you to easily expand your solar system should you want to in the future. Microinverters, like power optimizers, allow for panel-level monitoring so you can diagnose issues easily.
This is the most expensive inverter available, but is a great solution if shade is an issue on your roof. Since microinverters are installed on the back of the solar panels, repairs and replacements can be more difficult since the only access to them is on the roof.
The best solar inverter for a home will depend on the features you need from your solar power inverter and how you intend to use the energy from your solar panels. Solar inverters are one of the components that tend to fail first in a solar system, so it’s a good idea to check them often and invest in one that will last you a while. And if you have an RV, van, or tiny home, you might consider adding a solar inverter charger to your solar system installation to fulfill your energy needs.
A solar inverter charger is a more advanced version of a standard inverter. Inverter chargers can not only turn DC to AC, but they can charge a battery bank when shore power is available, ensuring you have constant access to energy, which is convenient for areas that don’t get enough sunlight to charge your battery bank. An inverter charger is handy if you:
An inverter charge fills the batteries when they’re low and stops the electricity generated from the panels from reaching the batteries when they’re full.
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.
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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.
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.
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.
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.
Centralized location
Cheaper option
Easier to access for service
Easier to install
DC power optimizers can help performance
Less productive
Weaker warranties
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.
Stronger warranties
More efficient
Last longer
More expensive
Servicing can be more expensive
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.
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.