Power On - Solar Power

Jon Hughes, Mark Anslow

1st November, 2007

Every year, each square metre of the UK receives between 900 and 1200 kWh of solar radiation. Capturing just some of this energy could make a significant contribution to fulfilling our energy requirements.

Solar thermal technology, which produces hot water, has become very efficient even in northern climates. Newer versions using evacuated glass tubes are able to supply between 50 and 70 per cent of domestic hot-water needs.

Solar photovoltaic panels, which generate electricity, are currently dogged by high cost, both financially and in terms of the heat energy used to melt the silicon in the cells. Although in most locations in the UK you will still eventually see both an energy and cash payback, neither the economics nor the thermodynamics are as attractive as those for its thermal cousin.

This could be set to change with the arrival of ‘thin-film’ photovoltaics, which use conducting chemicals that can be ‘sprayed’ or ‘printed’ onto glass or plastic backings, avoiding the high-energy processes associated with conventional manufacturing. However, many of the new thin-film technologies rely on heavy metals such as cadmium, or nano-scale particles such as titanium dioxide molecules or carbon nanotubes. If we are to accept the efficiency benefits brought by these technologies, we must make sure that manufacturers have stringent ‘end-of-life’ procedures in place to...

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