What is a solar inverter?

Solar panels aren't the only component to consider when evaluating your solar system equipment. Solar power inverters play an equally important role in a solar system: they convert the electricity your solar panels create into a form that can be used by the appliances, lighting, and other electronics in your home. Once you understand how solar inverters work and the different inverters available for solar, the EnergySage Marketplace can help you compare solar quotes.

When the sun shines on your solar photovoltaic (PV) system, electrons within the solar cells start to move around, which produces direct current (DC) energy. Circuits within the cells collect that power for you to use in your home.

This is where your solar inverter comes in. Most homes use alternating current (AC) energy, not DC, so the energy produced by your solar panels isn't useful on its own. When your solar panels collect sunlight and turn it into energy, it gets sent to the inverter, which takes the DC energy and turns it into AC energy. At that point, your solar electricity can power your appliances and electronics, or if you're producing more electricity than you need, it can feed back into the grid.

All inverters have the same essential task: convert DC solar energy into useful AC energy for your home. However, there are three different solar inverter technologies that you can choose for your solar panel system, and each of them works slightly differently.

String inverters: A standard centralized inverter

Most small-scale solar energy systems use a string inverter, also known as a "central" inverter. In a solar PV system with a string inverter, each panel is wired into a "string." Multiple strings (normally up to three) can be connected to your central inverter. When your panels produce energy, it gets sent to a single inverter, usually located on the side of your home, in a garage or basement. The inverter will convert all the electricity from your solar panels into AC electricity for your property.

Pros: String inverters are the lowest-cost option and are durable inverter technology. They are also the easiest to maintain because they are in an easy-to-access location.

Cons: A drop in the performance of an individual solar panel (i.e., from shading) can impact the output of all panels on an individual string. While multiple strings can accommodate multiple roof planes on the same inverter, string inverters may not be suitable for more complex system designs or roofs with regular shading.

Best for: Properties with "uncomplicated" roofs that get consistent sun throughout the day and homeowners looking for lower-cost solar PV systems.

Power optimizers: A panel-located option to pair with a string inverter

Power optimizers can be considered a compromise between string inverters and microinverters. Like microinverters, power optimizers are located on the roof next to (or integrated with) individual solar panels. However, systems with power optimizers still send energy to a centralized inverter.

Power optimizers don't convert the DC electricity into AC electricity at the site of the solar panel. Instead, they "condition" the DC electricity by fixing the voltage sent to the string inverter. A system that pairs power optimizers with a string inverter is more efficient than one that uses a string inverter alone in shading scenarios.

Pros: Like microinverters, power optimizers can improve the efficiency of your solar panel system if you have a complicated roof or frequent shading; however, optimizers tend to cost less than microinverters. They optimize the output of each panel to mitigate the impact any one shaded panel can have and also provide the benefit of monitoring the performance of individual panels.

Cons: A system that pairs power optimizers with a string inverter will cost more than a system with a standard string inverter option. As with microinverters, solar PV systems with power optimizers can be more difficult to maintain.

Best for: Homeowners with a slightly less than ideal roof for solar who are willing to pay more to increase the performance of their solar panel system but who don't want to invest in microinverters.

Microinverters: High-performance at a higher cost

If a string inverter can be considered a "central" inverter, microinverters are "distributed" inverters. Solar PV systems with microinverters have a small inverter installed at the site of each solar panel. Rather than sending energy from every panel down to a single inverter, microinverter systems convert the DC solar energy to AC energy right on the roof.

Pros: Having microinverters at every solar panel provides performance benefits, especially for systems with a more complicated design or that experience shading. Microinverters optimize the output of every panel at the panel to mitigate the impact of shading and allow for panel-level monitoring of your system.

Cons: Microinverters cost significantly more than string inverters and can be more difficult to maintain or repair in the event of a problem because they are located on the roof.

Best for: Systems with solar panels that face multiple directions, homeowners who want to maximize solar production in a small space, and properties that have "complicated” roofs with gables, chimneys, or other objects that can cause shade.

Now that you understand how solar inverters work, your next step is to decide which type is best for your solar PV system. Not every system design is suitable for string inverters; paying extra for optimizers or microinverters is not always necessary. Ultimately, there's no universal right or wrong answer, only what's best for your situation and needs.

EnergySage has additional resources that can help you decide on your solar inverter options:

• Comparing string inverters, microinverters, and power optimizers

• Microinverters vs. power optimizers: which panel-level option is best for you?

• Advantages and disadvantages of microinverters and power optimizers

Additionally, browse all types of solar inverters on the EnergySage Buyer's Guide, where you can compare inverter metrics across products like efficiency and warranties.

While you can continue to read about the different technologies, the best way to find out which option works for you is to review actual quotes from qualified local installers in your area.

Registering your property on the EnergySage Marketplace lets you review offers customized to your home and evaluate the costs and benefits of different inverter options. Customers who compare quotes on EnergySage can save 20% or more on their solar installation simply by evaluating their equipment, financing, and installer options.