Solar power is a source of energy in which sunlight is converted to heat or electricity. The technology used in these conversions varies from photovoltaic cells that convert the sunlight into electricity and large-scale concentrated solar power (CSP) systems that use mirrors, lenses and tracking systems to use the heat from the sun. All these systems require a form of storage for the energy when the sun is not available in the nights.
The CSP systems use lenses and mirrors that concentrate the sunlight into a concentrated beam that converges the heat energy to a small point, where a fluid, water or other, is heated. This heated fluid then is used to produce electricity just as in any conventional plant. It is essential that such technology is used in places that have a lot of sunlight throughout the year.
Photovoltaic cells are semiconductor devices that produce a small amount of direct current electricity when it absorbs sunlight. These cells can be increased and this leads to scalable systems that can be designed to produce the required amount of electricity. Most electrical appliances in use in today’s world require alternating current, and this requires the use of inverters to convert the electricity so that it can be used. Solar power conversion is also not available at night when the requirement of electricity is at a peak, and this requires that the electricity produced during the day be stored. This requires storage of the power in batteries, that can be charged during the day and tapped for discharge in the nights.
Present technology allows for a conversion efficiency of not more than 15 to 20 percent, and this is where research and technology are concentrated in order to improve this. Technology is also looking for solutions to improve storage capacities and superconductors are at the forefront of this quest. Technology has also evolved to use the electricity produced during the day to pump up water to towers or raised reservoirs and using this stored water to conventionally produce electricity at night. Another innovation is to use the power created during the day to be fed to electric utility companies and in return allowing the same amount of power to be drawn when required during the night from the grid.
Another technology that has created a fair bit of interest in solar power is the parabolic reflector, which is a refinement of the lenses and mirrors already in wide use. In this design, the dish or reflector is 12 feet in diameter and concentrates the energy to a level that is hundreds of time more than normal sunlight. The conversion of water into steam is instantaneous and the efficiency compared to photovoltaic cells is increased by a factor of 30 to 40.
Photovoltaic cells are made from highly refined silicon, which in itself is energy intensive, and research is constantly being made with newer materials that will decrease these costs and allow for flexible cells and other advantages that can lower the cost of producing solar power.