For those who despair at the daily news reports of record-breaking summer temperatures and the inexorable onset of global warming, take heed and take hope from the following numbers. The total installed generating capacity of photovoltaic (PV) solar worldwide in 2012 equalled 100 GW, or roughly the equivalent of 100 nuclear power plants. Solar PV is a silent, reliable technology (as long as the sun shines, but see Intermittency below for more on that) with no moving parts and a life expectancy of 20 – 40 years. This currently installed generating capacity uses PV cells that convert sunlight to electricity at efficiencies ranging from 9 to 14 percent, around 10 percent on average.
But there are a number of new generation PV cells in the works in dozens of countries around the world that have achieved efficiencies of 40% under laboratory conditions. These are mostly multi-junction PV cells coupled with a layer of light-focussing elements. These cells are currently too expensive for everyday use but have proved their worth in satellites and at remote research locations. As mass production techniques for each of these new technologies evolve, the price of such systems will come down within a decade to the affordability range of the current crop of monocrystalline cells that are the most commonly used worldwide.
Mass production in China has reduced the prices of monocrystalline cells so much in the past few years that they are now being used in rural areas in India. For a more detailed report by someone active in rural electrification efforts, see the link below.
Intermittency: Solar power is great as long as the sun shines, but what about after dark? Well, there’s wind, for one, but that is intermittent too. The evolving answer to that is storage technology (see my blog of 22nd June: Renewables – 13 next-generation battery designs). Link below
The bottom line is: systems are not perfect, and if anyone wishes to poke holes in an argument, they can and will. So in the end, choice of energy systems comes down to attitudes, opinions and habit. This fact lies at the heart of the renewable energy debate. Proponents of business-as-usual, nested comfortably as they are in a carbon-based economy that has reached a high degree of organizational efficiency over a century, see no need to change, and dismiss all thought of powering the world with renewables instead of coal, oil and gas as it is now. As Carl Jung pointed out nearly a century ago: Attitudes are more important than Facts, so a proponent of nuclear energy is likely to insist on the relative safety of nuclear technology (an argument that is statistically correct) until the day his own family is forced to shift from their home forever because of uncontrolled radiation release.
For anyone looking for more details on the PV technologies mentioned above, I can recommend the blog postings of the indefatigable Dave Elliott at http://blog.environmentalresearchweb.org/2013/08/17/solar-cells-1/