The Basics of Solar Power
Nice and topical in the middle of a British summer!
Essentially that big nuclear fusion reactor in the sky is the underlying element of almost all energy on this planet, so why not leave out the middle man and extract it directly? The good news is that you can, using solar panels (you probably knew that already). Ok, there are more ways of extracting power form the sun than solar panels, but seeing as the photovoltaic panels are become ever more popular that is what we will focus on here.
Basic principles of solar panels
The wizardry that forms a solar panel is glass, aluminium and silicon (with a hint of boron and phosphorous). The aluminium and glass is simply a casing for the truly clever bit - the silicon. Within a solar panel are multiple layers of silicon that have been 'doped' to become two different types of semi-conductor, which are enhanced by the presence of the sun's rays. These layers of silicon crystalline structures each produce a small voltage and through the use of tens of layers a significant amount of voltage can be generated (simplified in the accompanying figure). Typical efficiencies of domestic solar installations in the UK are around 20%. That might not seem like a lot but the solar radiation is such that 150-200W falls on every square metre on a clear day, compare that to the size of your roof and there is significant power absorbed.
The angle of a solar panel is important to the efficiency of its operation. In simple terms the angle should be similar to your latitude (with the panel inclined to face toward the equator). This may limit the peak power produced in the height of summer, but it gives the best distribution of energy across a full year.
There will always be the age old argument that it's always raining in the UK, but solar power generation is possible and in combination with storage (teaser for our next blog post) offers real potential. The costs of solar panels are continually decreasing with large volume production - the price per kW installed has fallen 60% in the last 10 years.
Want to produce more power - use more and more panels! The modular mature of the panels means that many can be combined to create an array of almost any given power level. There are even pilot projects on lakes and in the sea in and around China. In these calm waters the entire surface is covered with a matrix of solar panels to produce significant amounts of energy (for more information see this link).
As we touched on at the beginning there are some other ways of using the sun's radiation for power generation such as this solar plant in Spain (link), where the radiation is focused onto a single point to heat water to pass through as team turbine. There are also some pretty smart ways of using building design for water heating (trombe walls, sunspaces, solar chimneys), but that's a whole other topic!