Solar energy will be available for millions of years, and there is more than enough to supply all of the world’s energy needs. When electrical energy is fed back into power grid, a meter measures the electrical energy that has been supplied.įIGURE 10: SNOW BLOCKS LIGHT FROM REACHING THE SOLAR CELLS. When the battery is connected to an electric circuit, the chemical energy is transformed back into electrical energy. When a building is in a remote area, and is not connected into a power grid, the bank of batteries is necessary to store the electrical energy for night-time, when the solar panels cannot generate electricity.īatteries store electrical energy by transforming it into chemical energy.
For this reason a device known as an inverter must be inserted into a rooftop solar system to convert the direct current into an alternating current. However, electrical appliances operate on an alternating current (AC), a current which continually switches the direction in which it flows. The electrical current produced by a solar cell is a direct current.
Solar electricity for buildingsĪ rooftop solar system is the name given to the solar array on the roof of a building, together with the electrical circuit that must be set up to link the solar array to the electrical circuitry in the building. (The ‘positive holes’ virtually move upward, at the same time.) The result is the generation of an electric current.įIGURE 8: SOLAR PANELS ARE CONNECTED IN PARALLEL TO EACH OTHER IN AN ARRAY. Electrons from the top layer move downward. The top layer becomes negatively charged and the bottom layer becomes positively charged. When light shines on the top layer, a voltage is produced between the two layers. Where the two layers meet is termed a p-n junction. This is called a p-type layer because of these ‘positive holes’. The presence of boron atoms therefore creates what might be called ‘positive holes’. Boron atoms have one less negatively charged electron in their surface than silicon atoms. In the bottom layer, the silicon has been ‘doped’ with boron atoms. This layer is called an n-type layer because it can be a source of negatively charged electrons. This extra electron is held quite loosely, which is why a phosphorus atom releases an electron when it absorbs energy from a light photon. Phosphorus atoms have one more electron in their surface than silicon atoms. In the top silicon layer, shown in Figure 5, some phosphorus atoms have been inserted amongst the silicon atoms, in a process called ‘doping’.
#Solarcell physics windows
Others involve developing windows and roofs that can act as solar panels. Some research projects have developed flexible, light-weight solar cells that can be part of clothing or a back pack used by people such as hikers and field workers. are more environmentally friendly (made from less harmful substances, consume less of the Earth’s resources, produce less wastes when manufactured).can be used in a wider variety of applications.are more efficient (convert a greater the proportion of the energy from the Sun into electrical energy).Research teams across the world are doing some very exciting work using different designs and different technologies, including nanotechnology, in the hope of developing solar cells that: How a solar cell actually works depends on whether it is a silicon-based solar cell or another type of solar cell, such as an organic solar cell (which is made up of plastics), or a dye-sensitised solar cell (also known as a Grätzel cell). The video below, which was produced by the University of New South Wales, also shows how silicon-based solar cells work.įIGURE 3: A DYE-SENSITISED SOLAR CELL USES A PROCESS LIKE PHOTOSYNTHESIS TO TRANSFORM LIGHT ENERGY INTO ELECTRICAL ENERGY. The voltage of the cell will stay the same. If the light is more intense (brighter light) more electrons will be released each second and the electrical current will be bigger.This is a current that flows in one direction only. The resulting electrical current is in the form of a direct current (DC).The released electrons enter wires and travel around an electrical circuit.If the photons do not have enough energy, their energy is transformed into heat energy.If the photons have enough energy they cause the cell to release electrons.When photons shine on a solar cell, they are absorbed by the cell.
Light consists of little ‘parcels’ or ‘packets’ of energy called photons.The general principles by which all solar cells work are: Career Profiles – Climate Change and OceansįIGURE 2: FLOW CHART AND SANKEY DIAGRAM OF THE ENERGY TRANSFORMATIONS OF A SOLAR CELL.
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