Solar Panels. Image credit

Solar Panels. Image credit

ZIMSEC O Level Combined Science Notes: Photo-voltaic 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.

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