Solar Panel System GuideThe Department of Energy explains that the sun emits energy as electromagnetic radiation, and that photovoltaic cells absorb that light to create moving electrical charges. Silicon, the second most abundant material on Earth, does most of the work in today's panels. This guide follows the path from sunlight to the electricity in your home.
Sunlight as Energy
Everything starts with solar radiation. The Department of Energy states that the sun emits heat and light in the form of solar radiation, also known as electromagnetic radiation.
The DOE describes two main ways to capture that energy: photovoltaics, which turn light directly into electricity, and concentrating solar thermal power, which uses mirrors to focus sunlight into heat. Rooftop home systems use the photovoltaic approach.
The Photovoltaic Effect
Inside a panel, the conversion happens at the cell level. The Department of Energy explains that when the sun shines onto a solar panel, energy from the sunlight is absorbed by the PV cells in the panel, and this energy creates electrical charges that move in response to an internal electrical field in the cell, causing electricity to flow.
The DOE further describes that a PV cell contains a semiconductor material that absorbs sunlight and transfers the energy to negatively charged electrons, which then flow through the material as electrical current.
From Cell to Panel
A single cell produces very little power on its own. The Department of Energy states that an individual PV cell is usually small, typically producing about 1 or 2 watts of power, and that cells are often less than the thickness of four human hairs.
To get useful output, the DOE explains that cells are connected in chains to form larger units known as modules or panels. Silicon does most of the converting, and the DOE notes it is by far the most common semiconductor material used in solar cells and the second most abundant material on Earth after oxygen.
Getting Electricity to Your Home
The current a cell produces is direct current, but homes and the grid run on alternating current. The Department of Energy explains that current flows through metal contacts, the grid-like lines on a solar cell, before it travels to an inverter.
The DOE states that the inverter converts the direct current to alternating current, which flows into the electric grid and connects to the circuit that is your home's electrical system. That final conversion is what makes solar output usable by ordinary appliances.
Panel Lifespan
Solar hardware is built to last for decades with no moving parts in the panels themselves. The Department of Energy states that modules are expected to last 25 years or more.
Output fades slowly rather than stopping. The DOE notes that after 25 years, modules are still producing more than 80% of their original power, which is why panels keep contributing long after they pay for themselves.