Analysing the environmental effects of photovoltaics, on the whole we can say that unlike fossil-fuel based technologies, solar power does not lead to any harmful emissions during operation (like CO2, SO2, NOx and dust), which is a serious adventage of them. They don’t have any moving parts, less safety regulations are needed. However the production of the panels leads to some amount of pollution.
The environmental effects depends on the placement of the photovoltaics
also. If they are located where photosynthesizing plants would normally grow, they simply substitute one potentially renewable resource like biomass for another and takes away the place from the forests, other living organisms, or maybe agricultural areas. And if they are placed on the sides of buildings or fences, or rooftops (as long as plants would not normally be placed there), or in the desert they are purely additive to the renewable power base.Photovoltaics containes cadmium in cadmium telluride (CdTe) modules (CdTe is only used in a few types of PV panels). Cadmium in its metallic form is a toxic substance that has the tendency to accumulate in ecological food chains. The amount of cadmium used in thin-film PV modules is relatively small (5-10 g/m²) and with proper emission control techniques in place the cadmium emissions from module production can be almost zero. Most of these emissions actually arise through the use of coal power for the manufacturing of the modules, and coal and lignite combustion leads to much higher emissions of cadmium. Life-cycle cadmium emissions from coal is 3.1 microgram/kWh, lignite 6.2, and natural gas 0.2 microgram/kWh.
The harmful effect of cadmium can be easily avoided by recycling the old photovoltaics. Nowadays it is collected by some solar companies which reuse them and produce the new and more effective solar panels.According to life cycle analysis – contained producing processes, operation and waste state also – greenhouse gas emissions of photovoltaics were in the range of 25-32 g/kWh in 2008 and this could decrease to 15 g/kWh in the future. For comparison, a combined cycle gas-fired power plant emits some 400 g/kWh and a coal-fired power plant 915 g/kWh and with carbon capture and storage some 200 g/kWh. Only nuclear power and wind are better, emitting 6-25 g/kWh and 11 g/kWh on average. Using renewable energy sources in manufacturing and transportation would further drop photovoltaic emissions.On the whole photovoltaics have considerably less effect on the environment than the old polluting technologies. With solar power we can avoid a considerable amount of carbon emission and we can use an efficient, relatively cheap and environmental friendly technology for energy production.