Solar Energy – Turning Sunlight into Electricity

Solar energy could be used to generate electricity on a large scale if solutions were found for certain problems. At present it is too difficult to produce large amounts of solar energy and store it for times when the sun is not available such as overnight, on overcast days or at high latitudes. However let’s take a look at the way in which sunlight can be turned in a source of electrical power.

Solar energy keeps us all alive. The heat and light from the sun is what keeps the earth at the correct temperature. It is the sun’s energy that keeps almost all living organisms alive. It is the sun that determines natural systems and cycles. About 95% of the energy from the sun is given off as light that we can see. However the light that we can see is only a small amount of the sun’s total energy.

The "photovoltaic effect" is a process through which a PV cell changes sunlight into electricity. The light from the sun is made up of photons. These are particles of solar energy. Depending on their wavelengths, each photon contains different amounts of energy. When photons strike a PV cell they are reflected, absorbed, or pass right through.

So how does solar energy produce electricity? When a photon is absorbed it can generate electricity. Then the energy of the photon is transferred to an electron in the PV cell (a semiconductor). The electron escapes and becomes part of an electrical circuit. When it escapes it makes a tiny hole. The PV cell has a built-in electric field. This enables the cell to provide the voltage needed to drive the electrical current into a light bulb.