How do Solar Panels Work?

posted 3/7/22 by Anna Gdalevich

Solar energy is a big topic right now, but how does it actually work? Solar panels use photovoltaic (PV) cells that convert sunlight into electricity, in fact, that’s what the name means. Individual PV cells only generate about one or two watts of power, so they are connected together to form larger units called modules or panels. Panels can be used individually, but to boost them they are connected together to form arrays. Arrays are then connected to the electrical grid.

PV cells contain a semiconductor that only conducts electricity when energy is provided—the sunlight. When the semiconductor gets exposed to sunlight, it absorbs the light, and transfers the energy to negatively charged electrons, causing them to flow through the semiconductor as an electrical current. Other parts of the PV are designed to extract the electrical current and cause it to flow through metal contacts, which are the grid lines you see on solar panels. The current travels to an inverter that turns the direct current into alternating current that can go into the grid and eventually into homes. As long as sunlight is hitting the panels, electricity will continue to be generated. Solar panels generally produce between 250 and 400 Watts of power, though that depends on how much sunlight they get.

Solar panels do not just include PV cells, however. The cells are very thin and fragile, so they are placed between protective materials like glass or plastic in order to withstand outdoor conditions. Panels and arrays also often include mounting structures that keep the panels pointed towards the sun. Most importantly, solar panel systems have some method of storing the energy generated during the day. There are three ways to store this energy: battery storage, mechanical storage, and thermal storage. Battery storage is the most common, with energy being stored inside the battery using a chemical reaction. Thermal storage stores the energy by taking heat from the sun and using it to heat up water in an insulated tank and using the heat generated for energy. Mechanical storage transforms the excess solar energy into mechanical energy using a flywheel or compressed air. This mechanical energy is then transformed into electrical energy.

More and more people are adding solar panels to their homes in an effort to reduce their carbon footprint and use more renewable energy. Solar panels have become an accessible way for people to power their lives because they are relatively inexpensive—by energy standards. One drawback of solar panels is that the energy needs to be stored very well in order for the panels to be effective, and engineers are still researching and designing ways to store solar energy more effectively.

To see some solar power right in our own backyard, check out the Needham Solar Array! It generates as much power as what the town’s three largest buildings use in a year!