More and more property owners are thinking about fitting solar panels to capture solar energy to assist with fuel costs and maybe even sell some surplus electricity back to the national grid. But how do these space age looking devices actually work?
Solar Energy, quite obviously, is energy from the sun. It is intercepted by solar panels, which home owners normally put on our roofs or in a well exposed south facing position. As the suns rays strike our solar panels a voltage difference is established between alternate component layers withinthe panels, resulting in an electrical current, or at least the potential for an electrical current. By wiring up a large number of cells working identically and by adding inverters into the electronics we can gather electricity in a form which can be used by our appliances and for delivery to the national grid.
A fascinating feature of the process is imagining how the solar energy arrives at our Solar Panels in the first place. It was at one time imagined that light (including sunlight) propagated in the form of waves vibrating in a medium, which was termed the aether. There was an analogy with sound waves which use air or some other medium to travel through. Indeed the early nineteenth century scientist Thomas Young “proved” by his famous two slit experiment that light did indeed travel in this way and was wavelike in nature. Later that century however, attempts to find the aether proved fruitless, accurate experiments by Mitchelson and Morley suggestingthat it was almost certain that the aether did not exist. But, if you remove air, sound cannot travel, so if there is no aether how can light manage to propagate itself?
Experimenting with the photoelectric effect in 1905 lead Einstein to the conclusion that light is in fact made up of particles, known as photons, and so needs no medium, aether or otherwise. So our present thinking of how our solar panels receive energy is to think of them being bombarded by a flow of photons from the sun, each one imparting energy on impact which increases the energy of electrons in the solar panels, thus setting up the voltagedifference. (this is actually known as the photovoltaic effect because the energy gathered builds up a voltage difference between layers in the panel.)
This all sounds quitereasonable, but remember Thomas Young? Well his light experiments proving the wave nature of light remain valid to this day. The wierd fact that light can, perhaps should, be regarded sometimes as a particle phenomenon and sometimes a wave phenomenon gives rise to the still mysterious business of quantum theory, wherein we must contemplate very tiny particles actually being in two places at once!