Since electric power, based on fossil fuels, once considered inevitable, pollutes our environment and destroys valuable natural resources, scientists are looking for alternative, clean, natural resources. The answer is right in their back yard. The energy produced from natural sources has been around for hundreds of years – a simple water cycle or windmill. Due to the invention of electricity and the invention of an electric generator, hydroelectricity – or electricity generated from the tremendous power of water over dams – has been widely used. More sophisticated technologies and the discovery of new materials have led to more direct and efficient ways to convert natural energy into natural energy. Photovoltaic cell and solar cell wind turbine are two examples
Solar cells work by taking solar radiation and directing it into direct current. The solar cells are the Greek word selenium, which means ‘moon’. About 20 years ago, camera light meters were operated by selenium cells. Since selenium releases only a fraction of the energy it releases, scientists are searching for more efficient substances. Silicon, one of Earth’s most abundant elements, converts sunlight into electricity. Today we use solar cells. The solar cell contains a very thin silicon and a fine metal grid is applied on it. The grid ripens electrons from silicon without shade from the sun. A cell produces very little electricity for practical use, so most cells are usually connected in hierarchy.
Although you can buy solar cells at many electronics stores, the abandoned old model portable radio provides the raw materials to make your own solar cell line. The current output is small, but you get a response from your galvanometer. Open the back of the radio with a screwdriver and remove the selenium rectifier from the inside (unplug the radio or remove the batteries first). The rectifier has a panel of six plates, with a metal base at the ends of the copper-brown selenium layer. With a little cleaning and proper connections, each plate acts as a cell.
Carefully trim the plates from the rectifier and remove any paint that is lacquer thin on a soft cloth. Avoid massage – you don’t want to scratch the delicate selenium surface. Plates to a strip of cardboard, glue the metal side down. Keep them equal. Cut the red wire into six 2-inch (5-cm) pieces and the blue wire into six 4-inch (10-cm) pieces. Place the pieces in pairs. The thin foil is cut into small squares, large enough to serve as contact pods for wire tips. Now, with a small solder, connect the ends of the red and blue strips to the contact pods, leaving the other ends free.
Using small strips of tape, attach the contact pads of the blue strands to the selenium squares (negative). Tape the contact pads of the red wires to the metal bases (positive). Divide the six blue strings into a long blue wire, which acts as a galvanometer’s negative lead wire. Divide the six red wires into one large red wire and act as a positive lead wire.
Shine a strong shine on your panels. Watch the needle swing when recording the current. With a powerful light source and several cells connected to the series, you can burn a 6-volt flashlight or power a small motor. Selenium rectifiers are difficult to find. They were on radio models made before the 1970s, but you should look for stores that sell used electronics parts. If you want to create a project that uses a lot of cells, buy silicone cells from Science Supply. Most are already wired and easily connected to the array.