How Solar works

Restored from the Empower Network archive (2011–2017), lightly edited to meet our current advertising standards. Views are the original author’s.

You’ve probably seen calculators with solar cells — devices that never need batteries and, in some cases, don’t even have an off button. As long as there’s enough light, they seem to work forever. You may also have seen larger solar panels, perhaps on emergency road signs, call boxes, buoys, and even in parking lots to power the lights. That is Photovoltaic energy at work.

Photovoltaic energy

Photovoltaic energy is the direct conversion of light into electricity at the atomic level. Some materials exhibit a property known as the photoelectric effect that causes them to absorb photons of light and release electrons. When these free electrons are captured, an electric current results that can be used as electricity.

Cells to Panels to an Array

A number of solar cells electrically connected to each other and mounted in a support structure or frame is called a photovoltaic module. Panels are designed to supply electricity at a certain voltage, such as a common 12 volts system. The current produced is directly dependent on how much light strikes the panel. Multiple panels can be wired together to form an array. In general, the larger the area of a panel or array, the more electricity that will be produced.

This energy generated by the panel, in the form of direct current (DC), is transmitted to the inverter. The job of the inverter is to convert the DC power the solar panel has generated to alternating current (AC) that is transmitted on the grid.

The inverter converts DC to AC by using two switches which convert the positive only DC power to an alternating positive to negative AC power. The inverter will then step up the voltage from 12 volts to 120 volts, which is the voltage used throughout the US electrical grid. This conversion of voltage is what allows a 12 volt DC solar polar to be tied into a 120 volt AC grid.

 Grid tied solar means that your solar array is directly connected to your utilities grid. Your array acts like a generator and produces energy that is first used by you and any extra is sold to your electric utility. If you’re generating enough electricity to support yourself then your electric bill is considerably lower. However if you use more energy then your solar array generates, your utility will bill you for the difference (net).