5.14 Environmental impact
Everything we manufacture and use on a large scale has an environmental impact, and PV is no exception. There are two factors to consider here. First is the effect on the environment of any materials used in the manufacture of cells, modules, arrays, systems and finished installations. Second is the effect of embodied energy – that energy invested in the manufacture and disposal of exhausted or out-of-date installations. The assessment of these factors are brought together in a life cycle analysis in terms of the inventory from 'cradle to grave' of pollutants released and of the total energy used. These figures can be compared with the relevant figures for conventional electricity generation of the same capacity.
PV modules have a pretty clean sheet during their operational life. They emit no pollutants. Fossil fuel energy used in production, installation and decommissioning, however, gives rise to both embodied energy and net emission of pollutants such as carbon dioxide (CO 2 ), sulphur dioxide (SO 2 ) and the oxides of nitrogen (N 2 O, NO and NO 2 , collectively called 'nox', i.e., NO x ) and particulates.