Solar panels aren’t the only component that you should be thinking about when you evaluate 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 that are in your home. Once you understand how solar inverters work, and the different types of inverters available for solar, the EnergySage Solar Marketplace can help you compare solar quotes with different inverter types.
How solar inverters work in a PV system
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 energy 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.
Comparing solar inverter technologies: string inverter vs. string inverters with power optimizers vs. microinverters
All inverters have the same basic 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 “centralized” inverter. In a solar PV system with a string inverter, each panel is wired together into “strings.” When they produce energy, it all gets sent to a single inverter, which is usually located on the side of your home, in a garage, or in your basement. The inverter will convert all of the electricity from your solar panels into DC electricity for your property.
Pros: String inverters are the lowest-cost inverter option, and are a “tried and true” inverter technology. They are also the easiest to maintain, because they are in an easy-to-access location.
Cons: If your system uses a string inverter, it will only produce as much useful electricity as its least productive solar panel. Electricity production for a system with a string inverter can “bottleneck,” or be dramatically reduced, if just one or two panels are in the shade or aren’t operating properly.
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 thought of as 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. Rather, they “condition” the DC electricity by fixing the voltage of the electricity, at which point the electricity is sent down 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.
Pros: Like microinverters, power optimizers can improve the efficiency of your solar panel system, and they tend to cost less than microinverters. They also offer the benefit of monitoring the performance of individual panels, and systems with power optimizers can still produce significant energy even if one or two panels are underperforming.
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 that include power optimizers can be more difficult to maintain.
Best for: Homeowners who are willing to pay more to increase the efficiency of their solar panel system, but who don’t want to invest in microinverters.
Microinverters: high-performance inverter for complex systems
If a string inverter can be considered a “centralized” inverter, microinverters are “distributed” inverters. Solar PV systems with microinverters have a small inverter installed at the site of each individual 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: Because they are located on the roof near the solar panel, microinverters are more efficient than string inverters at converting energy. Systems with microinverters will still produce energy, even if one or two panels in the system are underperforming. Microinverters also make it possible to monitor the performance of specific panels, which makes it easier to identify production issues if they should arise.
Cons: Microinverters will cost significantly more than a string inverter, 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.
Choosing the best inverter option for your home
Now that you understand how solar inverters work, your next step is to decide which type is best for your solar PV system. At the end of the day, the choice comes down to how much you’re willing to pay for additional performance, and whether you are prepared for the possibility of additional maintenance.
EnergySage has additional resources that can help you make a decision about 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
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.
When you register your property on the EnergySage Solar Marketplace, you can review offers that have been customized to your home and evaluate the costs and benefits of different inverter options. Customers who compare quotes on EnergySage can save 20 percent or more on their solar installation simply by evaluating all of their equipment, financing, and installer options.