SOLAR CELLS

SOLAR CELLS:

Visible light can be converted directly to electricity by a space-age technology called a photovoltaic cell, also called a solar cell. Most photovoltaic cells are made from a crystalline substance called silicon, one of the Earth’s most common materials. Solar cells are typically made by slicing a large crystal of silicon into thin wafers and putting two separate wafers with different electrical properties together, along with wires to enable electrons to travel between layers. When sunlight strikes the solar cell, electrons naturally travel from one layer to the other through the wire because of the different properties of the two silicon wafers. A single cell can produce only very tiny amounts of electricity-barely enough to light up a small light bulb or power a calculator. Nonetheless, single photovoltaic cells are used in many small electronic appliances such as watches and calculators.

ELECTRICITY STORAGE

Solar panels make electricity in all kinds of conditions, from cloudy skies to full sunlight, in all seasons of the year. But they don’t work at all during the nighttime! To make electricity available after sundown, the energy must be stored during the day for later use. The usual storage device is a rechargeable battery. The batteries used with solar arrays must be able to discharge and recharge again many times. They contain special parts and chemicals not found in disposable batteries. They are also usually larger and more expensive than their disposable cousins. Besides solar panels and rechargeable batteries, modern photovoltaic systems are usually equipped with some kind of electronic charge controller. The main job of the charge controller is to feed electricity from the solar panel to the battery in the most efficient manner and to prevent the solar panel from overcharging the battery. The charge controller also protects the solar panels from electrical damage.

SOLAR ELECTRICITY IN EVERYDAY USE:

Photovoltaic panels, like computers and other technologies, are getting cheaper and easier to buy. In fact, many people consider them a great alternative to gas-powered generators or connections to the regular electricity supply. Some countries such as Japan have encouraged businesses and communities to install solar panels on the roofs of new buildings to reduce the need for electricity from other sources. Many homes and businesses have both a connection to the commercial electrical supply system (often called the “electricity grid”). The solar panels can provide all or most of the building’s electrical supply during the day, and the grid supplies whatever other electricity may be needed during the night.