Page 17 - A Comprehensive Guide to Solar Energy Systems

Chapter 1 • Why Solar Energy? 9

In many developing countries, there is a surprisingly high level of cell/mobile phone
usage, despite a limited infrastructure for recharging the battery. Solar PV panels offer an
ideal way of solving the problem.
Little has been said of solar thermal energy in this chapter but it too can be used to raise
the standard of living for the almost one-third of the world’s population living without
electricity. Solar thermal energy offers a great way of heating water without the need for
burning cow-dung (a major cause of eye disease, especially in rural India) or wood, which
is often in short supply.
Although solar energy is a clean source of energy and has a much lower environmental
impact than any of the conventional fossil fuels, coal, oil, and gas its replacement of fossil
fuels is not going to be easy. First, the fossil fuel industry is well entrenched in our society
and we have become totally dependent on it. Second, fossil fuel, in all its manifestations,
is a wonderfully concentrated form of energy that packs a lot of energy into a small space,
when compared to the major renewable forms of energy. The concentrated nature of fossil
fuel, which has taken 2 billion years to accumulate, means the renewable forms of energy
are at a significant disadvantage. However, humans are being forced to adapt, albeit slowly.
There are three main driving forces for this. First, the burning of coal in huge quantities
in power stations is causing major smog problems with its accompanying respiratory
and other health issues (especially in China) and this is forcing governments around the
world (especially Europe and China), to consider seriously reducing their reliance on coal-
powered electricity generation and develop renewable energy sources. In Beijing, schools
often have to close because of smog and protective masks are a common day-to-day sight.
Second, pumping oil or gas from both offshore or onshore wells is becoming more and
more expensive, and this is particularly true in the case of oil wells where new sources are
found only in increasingly inhospitable areas, making mining difficult, expensive, and in
many cases environmentally disastrous.
Third, the price of renewable energy and, in particular, solar PV energy has decreased
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from $10 W in 2007 to less than $1.56 W for rooftop installations and $0.86 W for
utility solar farm installations in 2017. Solar energy is now beginning to offer competitive
prices with regard to energy from coal, gas, and oil [29,30]. This rapid reduction in price
over just a decade is far better than the equivalent rate of change for any other renewable
source of energy. This has led many to predict that soon solar PV will be the dominant
renewable form of energy. However, on a commercial basis, solar energy must do more to
out-compete traditional fossil fuels. Fossil fuels with their high energy density are just too
convenient and wind and solar power is variable, delivering power only when the wind
blows and the sun shines. Fossil fuel can deliver power when it is needed although their
extraction and combustion pollutes the environment. The saving grace of solar and wind
energy in scenarios of large penetration (e.g., >30%) will be linked to their integration
over large balancing zones and to the development of affordable energy storage technolo-
gies [31]. At the moment, battery technologies appear to be the most convenient storage
method with the lithium-ion battery leading the way.