What is a solar inverter?

Inverters aren't glamorous, but they're key to every solar panel system.

When you install a home solar panel system, the panels are just one piece of the puzzle. Another very important piece is the solar inverter—without it, you wouldn’t be able to use any of the electricity your solar panels produce.

A solar inverter converts the direct current (DC) electricity that solar panels produce into the alternating current (AC) electricity that our appliances run on. There are several types of solar power inverters and not all of them are made equal. We'll help you understand how solar inverters work and the different types available so you can choose the right one for your system.

Key takeaways

• Solar inverters convert your panels’ direct current (DC) electricity to alternating current (AC) electricity that your home and appliances use.
• There are three types of solar inverters: string inverters, power optimizers (used with string inverters), and microinverters.
• Inverters typically last between 10 and 25 years and will likely need to be replaced before your panels.

How does a solar inverter work?

Solar inverters convert the DC electricity your solar panels produce into the AC electricity that powers our everyday devices. If you thought all electricity was the same, you're certainly not alone. Let's back up a second:

• Direct current power flows in one direction. The voltage also remains constant. This allows it to be stored—so if you pair a battery with your solar panel system, the electricity it stores will be DC.
• Alternating current power is constantly switching direction. The voltage also fluctuates in a sinusoidal (basically a wave) pattern. So, AC electricity can more easily meet the power needs of all the various appliances throughout your home.

So, how exactly do inverters convert DC power to AC power? We don't want to bore you with the details, so we'll try to keep it pretty high-level.

1. When sunlight hits the solar cells that make up your solar panels, it generates DC electricity, which flows to connecting wires.
2. The wires connect the electricity to your system's inverter (or inverters depending on your setup).
3. The inverter contains a transformer, an electromagnetic device that changes the current's voltage level.
4. Devices called transistors rapidly switch on and off. When the DC power reaches a transistor that’s off, it’s forced to change direction. The back-and-forth eventually "tricks" the DC power into becoming AC.
5. The AC electricity flows from the inverter to your house's electric panel. If you don't need that electricity, it will either go to the grid or your battery, if you have one. Either way, it’s primed and ready to power our everyday needs.

If you're curious...

How inverters work with AC vs. DC solar batteries

If you pair your solar system with energy storage, the electricity flow will work differently depending on whether you have an AC- or DC-coupled battery system.

All energy is stored in DC format. With an AC-coupled system, the DC solar electricity flows from your panels to the solar inverter to become AC electricity. Extra electricity not used for your appliances flows to a separate storage-only inverter, which converts it back into DC power. When you need power from your battery, the stored electricity will be sent back through your storage-only inverter—three total inversions before it's used.

For a DC-coupled system, DC solar electricity flows from your panels to a charge controller and straight into your battery, staying in DC format the whole time. After the electricity charges your battery, a hybrid inverter converts it to AC electricity for use in your home. Any electricity the solar panels produce will be inverted only once (from DC to AC) as it flows from batteries, through hybrid inverters, and to your home appliances or the electrical grid.

Types of solar inverters

There are three types of solar inverter options to choose from: string inverters, microinverters, and power optimizers. (It’s important to note that power optimizers are used with string inverters.) All inverters work to convert DC solar energy into usable AC energy for your home, but each has a different method.

String inverter - Centralized and budget-friendly

What: Solar panels are connected by multiple strings that flow energy to a single, centralized inverter.

Pros:

• Affordable
• Easy to maintain
• Durable technology
• Can usually meet the full power output of solar panels (doesn't result in clipping)

Cons:

• One underperforming panel will disrupt the whole system
• Requires simple roof design with minimal shading
• Typically, shorter warranty coverage (10-12 years)

String inverter + power optimizer - Happy-medium

What: A string inverter setup with power optimizer devices installed on each panel, allowing them to act independently.

Pros:

• Compatible with most roofs
• Easy to maintain
• Durable technology
• Can usually meet the full power output of solar panels (doesn't result in clipping)
• Improves string inverter efficiency and monitoring

Cons:

• One underperforming panel will disrupt the whole system
• Expensive
• Harder to repair and replace compared to standard string inverters
• Typically, shorter warranty coverage (10-12 years)

Microinverter - High performance, high cost

What: Distributed, micro-sized inverters are attached to each solar panel.

Pros:

• Compatible with most roofs
• Allows panels to act independently
• Longer warranty coverage than most string inverters (~25 years)
• Makes it easy to expand your system

Cons:

• Expensive
• The hardest of the three options to repair and replace because everything is on the roof
• Inverter output sometimes can't match the solar panel output, resulting in clipping

Choosing the best inverter option for your home

With many pros and cons to consider, you may have a hard time choosing which inverter option is best for you. As mentioned, a standalone string inverter typically makes the most sense if you have a sunny, fairly uncomplicated roof. (Think: minimal shading and less than 6 roof planes that would include solar panels.) If that’s not you, we’ll take some pressure off by saying there’s no universal right or wrong answer between a string inverter plus power optimizer setup and microinverters. We suggest talking to your installer to see what's best for your situation and needs.