What Is a Solar Inverter and How Does It Work?

Solar panels transform sunlight into energy, but you wouldn’t be able to use that energy in your home without the help of a solar inverter. This piece of equipment is an essential component in photovoltaic (PV) solar energy systems. But not all inverters are exactly the same. There’s a range of types, from large central inverters for commercial systems to the smaller types of inverters you’ll find at home. So, what is a solar inverter, and how does it work? This guide will help break down how solar powers your home.

What Is a Solar Inverter?

A solar inverter, also known as a solar power inverter, converts the direct current (DC) electricity created in your solar panels into alternating current (AC) electricity that you can use in your home. It’s a simple function, but it is entirely necessary. Here’s why.

When the sun hits your solar panels, it’s absorbed by the solar cell. This creates DC electricity, which is typically a lower voltage and can only run in one direction. However, it’s not compatible with the appliances in your home. Instead, the solar inverter transforms the current into AC electricity (120/240 volt power), which is the type of electricity used in your home.

How Do Solar Inverters Work?

Though the purpose of a solar inverter is simple, the actual mechanics are pure science. It works like this:

• It starts with a PV cell. Your solar panels work because they have photovoltaic cells. These cells contain layers of a semiconductor material (typically crystalline silicon) that carry either a positive or negative charge. The layers are connected by a junction. 

• The sun hits the cell. When the sun hits your solar panels, it’s absorbed by the cell. The energy bounces between the negatively and positively charged layers, creating an electromagnetic field.

• Your cell creates DC electricity. The electromagnetic field knocks electrons loose from the atoms in the PV cells. The electrons flow through the junction that connects the layers, creating a direct electrical current. 

• The current travels to the inverter. Your solar panels are wired into a solar inverter. The current flows from the cells to the inverter. It may make some stops along the way, like if you use a power optimizer (which optimizes energy output) or store your energy in a solar battery. 

• The inverter converts the power. There’s a transformer inside of your inverter that changes the voltage of the current. As the current hits the inverter’s transistors, the transistors shut off, which forces the current to change direction. This movement turns the direct current into an alternating current.

Most solar inverters last 10 to 25 years and carry a warranty that matches the average life span. You’ll likely need to replace your solar inverter before you need to replace your panels.

Types of Solar Inverters

There are a few different types of solar inverters that you can use for a residential solar energy system.

String Inverters 

This is the most common type of solar inverter. Several panels are wired into a single string inverter, which converts their collective energy.

Microinverters 

Microinverters are generally used as a workaround for systems where panels may get uneven sunlight or are obstructed by shade. Each panel connects to its own microinverter, which converts the individual current. If some panels have reduced output, the rest of the panels aren’t dragged down.

Hybrid Inverters 

Hybrid inverters are solar inverters that contain a backup battery and store excess power. These are often used for larger systems, off-grid systems, systems prone to power outages, and those that can utilize net-metering programs.

Power Optimizers 

Power optimizers don’t convert currents—they regulate them. This device regulates the current to ensure each panel has optimum output before the electricity is sent to a string inverter. This prevents power loss and increases efficiency. 

Solar Inverter Costs

For most homeowners, solar inverters cost $1,000 to $3,000—though you could spend as much as $5,000 if you have a large system and use high-end inverters. String inverters cost $800 to $2,500, with an additional $50 to $200 per panel for power optimizers. Each microinverter will run you $150 to $350, and you’ll need one for each panel in your system. Hybrid inverters are the most expensive, running $1,000 to $5,000.

Choosing a Solar Inverter

You’ll need a solar inverter close in wattage to the panels it needs to support. If you have a 6-kilowatt system, you should look for a 6,000-watt inverter. If you aren’t sure, you can use a solar panel inverter size calculator or speak with a local solar panel installer who can help you decide which inverter works best for your home. 

Most homes use string inverters, especially when all of the panels receive even sunlight and face the equator (south if you’re in the Northern Hemisphere). Nonetheless, there are some instances where you may want to add power optimizers, choose microinverters, or spring for a hybrid inverter:

• Some of your panels are obstructed by shade

• Your panels face different directions

• Your roof can’t support south-facing panels 

• You experience frequent power losses

• You experience frequent cloudy or dusty weather

• You want to participate in net metering