Solar energy can be made usable in three different ways. Photovoltaic cells convert sunlight into electricity. Solar thermal systems use the sun's energy to heat water. Concentrating solar power focuses sunlight to heat water. The resulting steam drives a turbine, producing electricity. However, solar energy is more expensive than other types of energy, and the technology is also inefficient. Solar panels and thermal concentration power plants need to cover large areas to produce enough electricity. In addition, harmful toxic chemicals are used in the production of photovoltaic cells.
Solar energy is more expensive than other renewable energy sources and fossil fuels. The cost of a two-kilowatt (kW) solar energy system is approximately £29,250, and it cannot fulfil more than half of a typical American household's requirements. So, it is not as useful when it is compared to electric generation costs and other fuel sources, such as coal and gas. Furthermore, solar energy prices vary according to geographical variation in the amount of light available. Photovoltaic power is driven up in price by the high costs of the materials and the manufacturing process.
Photovoltaic cells only have a short lifetime. They are expensive as well. The initial set up cost is high. The price of solar thermal systems for residential use varies, depending on the size of household; it costs between £5,200 and £6,500 for a 1kW system anywhere in the United States. In 2010, a conventional water heating system that uses gas or electricity would be cheaper ($2,000 to £2,600).
Although the technology has been gradually improving, solar energy is not efficient. The most efficient photovoltaic systems reach an efficiency of about 30 per cent. Concentration technologies, such as parabolic troughs (a kind of solar thermal energy collector), reach 20 per cent efficiency.
Solar energy can only be used intermittently, according to the weather and time of the day. There is no adequate means of storing the energy for later use, although technologies are being developed. The current storage equipment is currently expensive and can contribute 70 to 80 per cent of the cost of a system if it is required.
Size and Appearance
Some homeowners associations have attempted to prevent people from incorporating solar energy technologies into their homes, citing concerns about damaging the neighbourhood's aesthetic appeal. People have also objected to large solar plants that would cover large areas of ground.
The manufacture of photovoltaic cells involves the use of toxic and hazardous chemicals. These present a risk to workers during production and are an environmental hazard. The manufacturing process produces a small amount of potentially harmful waste that contains such chemicals as selenium and cadmium. The solar panels themselves contain these toxic materials too and need to be disposed of carefully at the end of their lifetime.