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How Do Solar Panels Work?

In simple terms, solar panels turn sunlight into electricity, an inverter converts that electricity into the form your home uses, and anything you do not use flows out to the grid. Here is what happens at each step.

Sunlight becomes electricity (the photovoltaic effect)

A solar panel is made up of many photovoltaic cells, usually built from silicon. When sunlight hits a cell, it knocks electrons loose, and that flow of electrons is an electric current. This is called the photovoltaic effect, and it is why panels are often called "PV" panels. The more direct sunlight a panel receives, the more electricity it produces.

From the roof to your outlets

The electricity a panel produces is direct current (DC), but your home runs on alternating current (AC). That is the job of the inverter: it converts the panels' DC output into AC power. The converted electricity then flows into your home's electrical panel and powers your lights and appliances just like grid electricity does — your devices cannot tell the difference.

What happens to extra power

Your panels often produce more than you use in the middle of a sunny day. That surplus flows out to the utility grid, and in most areas you receive a credit for it through net metering or net billing. At night, or on dark days when your panels produce little, you simply draw power from the grid as usual (or from a battery, if you have one). For most homes the grid acts like a backup and a savings account rolled into one.

The main parts of a system

• Panels — capture sunlight and generate DC electricity.
• Inverter — converts DC to the AC your home uses (either one central inverter, or small "microinverters" on each panel).
• Racking — mounts the panels securely to your roof.
• Meter — measures the power you draw from and send to the grid.
• Battery (optional) — stores surplus energy for later or for backup.

What affects how much you generate

The big factors are your location and sunlight, the direction and tilt of your roof, any shading from trees or buildings, and the size and efficiency of your system. The free SunWise solar calculator takes your state and system size into account to estimate how much you could produce and save. To go further, see how many solar panels you need and how much they cost.