When initially deciding the four topics to start off my blog, I included solar because of its popularity. Solar energy is a very broad topic and this post is not intended to cover all possible aspects and applications of solar. Instead, I will focus on photovalic applications and not other more sophisticated uses, as many are still in the research phase.
In simple terms, photovalic modules are used to collect solar energy which is then transformed into electricity. This electricity can either be AC or DC. In some instances, such as calculators, garden lighting, and other applications with very low electrical requirements.
However, when compared with traditionally generated electric power, solar is not economically efficient. The US Department of Energy states:
"The cost of larger PV systems (greater than 1 kW) is measured in "levelized" costs per kWh—the costs are spread out over the system lifetime and divided by kWh output. The levelized cost is now around 30 cents/kWh." http://www1.eere.energy.gov/solar/pv_quick_facts.html
As of January, 2008 the US average cost per kWh was 10.2 cents, well below the solar cost of 30 cents/kWh. Again, this figure comes from the US Department of Energy, http://www.eia.doe.gov/cneaf/electricity/epm/table5_6_a.html
So, why is solar so popular? In many respects, it is the new, shiny toy. Also, there is the allure of "free" electricity. However, as the old adage states, "If its too good to be true, then it probably is." One has to recall that to convert one form of energy to another, there is loss. When one burns coal, heat is the main output, true also for any fuel that burns. What makes coal and fossil fuels in general, more efficient is that their combustion creates very high amounts of heat per unit. This heat is generally used to create steam, which then turns turbines (dynamos) to create electricity.
Solar has potential, but at today's cost points, it is only economically efficient in certain applications. Personally, I am renovating my home and looked into solar roofing shingles, as well as other PV collectors. In both cases, their cost well exceeded the benefits. However, a solar-powered attic fan may be just the thing.