Category Electricity from Sunlight:. An Introduction to. Photovoltaics

Life-cycle analysis

In the previous section we considered PV’s requirements for raw materials and land – two environmental issues that surface before PV production even begins. Further important environmental questions arise during a PV sys­tem’s lifetime, which starts with extraction and purification of raw materi­
als; proceeds through manufacture, installation, and many years of operation; and ends with recycling or disposal of waste products. The whole sequence is referred to as a life cycle, and it is important to appreciate its environmental consequences. Note that this form of life-cycle analysis (LCA) is not the same as the classical economic version introduced in the previous section, which deals with cash flows and financial decisions...

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Environmental aspects

Подпись: Environmental aspects
Raw materials and land

The main environmental credentials of PV are established beyond doubt: its important contribution to reducing carbon emissions; cleanliness and silence in operation; lack of spent fuel or waste; and general public accept­ability in terms of visual impact. We have already referred to such advan­tages at various points in this book. But there are further environmental considerations as PV accelerates into multi-gigawatt annual production – can Planet Earth provide the necessary quantities of raw materials, and is there enough land available for hundreds of millions of PV modules?

We start with the issue of raw materials. One point is clear: in so far as PV’s future is based on silicon solar cells, there is no problem...

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Rural electrification

So far we have been concentrating on economic aspects of grid-connected systems and the ways in which governments in developed nations encour­age the development of PV markets. Passing reference has been made to stand – alone PV systems, noting that the chief competitor for supplying electricity in remote areas is generally the diesel generator. But all this relates to relatively wealthy nations including those that have driven PV’s spectacular growth over the last decade.

There is another important dimension to the terrestrial PV story, and it concerns the provision of relatively small amounts of solar electricity to families and communities in the developing world, who have little prospect of buying and maintaining diesel generators, and no prospect of connection to a conventional ele...

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Financial incentives

We have already noted that PV, an exciting new technology with major environmental benefits, both justifies and deserves the support of govern­ments wishing to accelerate market growth and counter the effects of global warming. Japan showed the way in 1994 with a 70 000 solar roofs program. Germany, after succeeding with its own 100 000 roofs program, went from strength to strength after 2004, thanks to improvements in its groundbreak­ing renewable energy legislation. Spanish government legislation led to an extraordinary burst of activity in 2008 when 2.7GWp of PV capacity was installed in a single year (you may like to refer back to Section 4.5 on large PV power plants). The USA, held back during the years of the Bush admin­istration, is now surging ahead...

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Economics and the environment

6.1 Paying for PV

6.1.1 Costs and markets

One of the most encouraging aspects of the current PV scene is the steady reduction in costs. Continuing improvements in cell and module efficien­cies are making a substantial contribution; but above all it is the sheer volume of production in state-of-the-art factories using highly automated facilities that is driving down costs. Right back in Section 1.4 we introduced the ‘1 earning curve’ concept to illustrate how, for a wide range of manu­factured products, costs tend to fall consistently as cumulative production rises. Figure 1.11 confirmed that PV costs have fallen for more than two decades by around 20% for every doubling of cumulative production – and the trend continues...

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On land and sea   Figure 5.32 Two solar-powered cars, entered by the Universities of Michigan and Minnesota, speed at over 100 kph along a Canadian highway during the 2005 North American Solar Challenge (Wikipedia).   Figure 5.33 It has become commonplace for sailors to install PV modules on the decks of ocean-going yachts to power cabin lighting, services, and navigation equipment. There is now growing interest in making the sails themselves ‘photovoltaic’ (EPIA/Shell Solar). &nbsp

Figure 5.34 This installation in the Libyan desert provides cathodic protection, an important application of PV that helps minimise corrosion of metal structures including pipelines (EPIA/Shell Solar).

Подпись: Figure 5.34 This installation in the Libyan desert provides cathodic protection, an important application of PV that helps minimise corrosion of metal structures including pipelines (EPIA/Shell Solar).
In heat and cold

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Figure 5.35 A PV array produces electricity for a meteorological station in Greenland. In this high northern latitude the vertical array captures much of the available sunlight, and solar cell efficiency is enhanced by the very low temperatures (EPIA/Shell Solar).

 

For education and information

Figure 5.36 An increasing number of schools worldwide use PV arrays to generate valuable electricity and stir their students ’ imagination for the future of renewable energy...

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Far and wide

The applications described in previous sections represent a broad range of technical, economic, and social objectives. Yet the scope and geographical spread of stand-alone Pv systems stretch much wider. We end this chapter with a few more photographs and captions to illustrate some of Pvs past and present successes and help stir the imagination for its future potential.

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Solar-powered boats

Boats powered by sunlight represent one of the most successful and attrac­tive applications of PV in the field of sustainable transport. Less well-
known to the public than the solar car races that have achieved international fame in Australia and the USA, solar boating has recently made headlines with a growing number of international events and a transatlantic crossing. Solar circumnavigation of the globe is a definite prospect. Unlike road vehicles, boats do not have to climb hills or travel at high speed and they require surprisingly little power for propulsion in calm conditions. This makes solar-powered boating on lakes, rivers, and canals relatively inexpensive and opens up a new market for PV in an important leisure industry.

The low power levels needed to propel boats at modest sp...

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