Photovoltaic cells/Solar Panels

• Solar cells convert radiation from the sun into electrical energy
• These cells are mad from silicon
• Which is a semiconducting material
• While most metals are good conductors of electricity because they have
• a large number of free electrons
• Which move when a potential difference (voltage) is applied
• and non metals and other materials have very few electrons for conduction
• As their electrons are tied are and thus act as insulators
• Non-conductors are a third group which fit in between insulators and conductors
• semi-conductors such as silicon can have electrons that break free
• The higher the temperature of the semi-conductor
• the more free electrons there are
• The resistance of these semiconductors decreases with temperature
• In conductors resistance increases with temperature
• In bright sunlight each solar cell can produce about 0.5 V and
• a current of 0.03 A
• The solar cells can be connected in series to increase their voltage
• And/or in parallel to increase the current
• The result is known as a solar/photo-voltaic panels
• Solar panels are commonly used in rural parts of Zimbabwe where people live off the national electricity (ZESA) grid
• They are still considered expensive as the panels and requisite batteries are expensive to buy and maintain
• They are also used to power space satellites

To access more topics go to the Combined Science Notes page.