| Photovoltaic Solar Panels generate electricity by using | | | | High School physics taught us that the light from the |
| a phenomenon first discovered in 1839 by a young | | | | sun is made up of packets of energy called Photons. |
| scientist called Edmund Becquerel. This phenomenon, | | | | Each photon carries an amount of energy |
| called the photovoltaic effect occurs when certain | | | | corresponding to the wavelength of its light. When a |
| materials produce electric currents as they are | | | | photon strikes a photovoltaic solar panel it can do one |
| exposed to light. | | | | of three things. It can pass straight through, be |
| A photovoltaic solar panel is essentially a huge series | | | | reflected, or be absorbed. If the photon is absorbed, its |
| of semiconductor PN junctions. One half of each | | | | energy is absorbed by an electron in an atom of the |
| junction is electron deficient, the other half electron rich. | | | | solar cell enabling it to escape from its normal position, |
| The photovoltaic cell is designed to create an electric | | | | cross the junction and fill a hole. The electrons then |
| field across the junction between two halves of the | | | | flow through a load (e.g. charging a battery, lighting a |
| crystal, and electrons flow from the rich half to the | | | | light, or powering a motor), and complete the circuit by |
| poor half. A potential barrier exists between the p and | | | | recombining with the holes they left behind. In so doing |
| n-type sides of the crystal and this prevents further | | | | energy from the sunlight has been extracted and used |
| electrons from traveling across the junction until sunlight | | | | at an efficiency of around 5-15%. This process can be |
| hits the solar cell and releases electrons with enough | | | | repeated over and over again over the decades of |
| energy to overcome the barrier. | | | | lifetime of solar cells. |