Building Solar Panels. D.I.Y

How does solar power work?

In a cell you have a PN junction, this is silicon doped with boron and phosphorous.
the P layer and N layer are separated by a depletion zone, and as light hits the thin P layer it breaks the bond between the atoms in the depletion layer. Electron Hole Pairs are created and the holes are sent to the P side, the electrons the N. On average a single cell can produce 0.45 Volts and approximately 35mA per square centimetre.

You arrange the cells in series and parallel arrays, to make a panel. Arranging in series increases the emf (Volts) produced, in parallel you increase the current.
The panel on it's own can be used to power small devices, but for anything larger you need to have the panels charging what is known as a deep cycle battery; this is a battery that can stand being charged and discharged at the same time over many thousands of cycles. A good one will last at least 5 years. You have to regulate the input to the battery and this is done by a device between the battery and the panel(s) which is unsurprisingly called the battery regulator. It has to be matched to the battery, commonly 12 and 24 Volts.
Once again, you could use the battery directly, but if you want to run an electric light or a water heating system, you need the battery powering an invertor to produce 240 V in the UK (120 in America). Your house can now be fitted with a “green ring” in which the supply comes only from the solar installation system or, and this is the preferred choice in the USA, you can have a “grid tie” in which both your system and the National Grid supply power (I'm not sure that this is approved in the UK- it may mean a special permission that you are unlikely to get). Another popular way to do it is to have your solar system operating your hot water supply.
If you go to a supplier of electrical parts you can buy small solar panels, and if you hook a couple together in parallel and hook the pairs in series you can get enough to power a small transistor radio. I did this as an experiment last March, and ran my shed radio all summer long off them.

Finally, your panels can be fixed in a stationary position or mounted as a tracker to follow the Sun. In the latter case it does mean that your panels are generating at peak efficiency all the time, but it also means that they are using some of the energy generated in the movement mechanisms. Debate rages about whether this makes them more efficient or not, but it does make your system a bit more expensive. In the UK it's probably not worth it, but in California it probably is.

Grid Ties;
http://en.wikipedia.org/wiki/Grid_tie_in…

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