House Solar Power

I've acquired 4 x 20W solar panels and feel I should put them to good use. I built a wooden panel to mount them on the shed. They face south and aren't shadowed by the house too much. Of course, our south-facing roof on the house would be the ideal location but this will do as a trial.

In fact, there are government grants for domestic installation covering up to 50% of costs at present. The only catch is that it has to be an approved system and fitted by an improved supplier. The web site has lists of these. But you are still looking at £4-5000.

Of course Solar water heating has a much quicker return on your money and there are amateur groups. There are even some Cambridge based people with web sites detailing their setup.

I recently bought a 600W continuous inverter (Surge 1500W I think) from ARD Electronics which seems to have some of the cheapest models. I haven't done anything with this other than check it can power an economy light bulb from a car battery. We need a cheap source of batteries now. I noticed that the fan on the inverter runs all the time rather than being temperature controlled so this is bound to be inefficient. However I need to think about a proper control system anyway that only turns on the inverter when someone switches a light on - the current plan being that this inverter will be enough to power the lighting circuit and can switch back over to mains electricity when the batteries are flat anyway.

2004/2005: With the shed move to the end of the garden, the panels have also moved up the garden. Unfortunately they aren't on the shed roof, so get quite a bit of winter shadow from neighbours sheds. Stuck a monitoring device on the system and this has started to collect data which can be interrogated and monitored real-time on our home PC. There are about 280 Ah of 12v batteries in the system and there is a relay wired in, powered from the inverter mains inverter, such that the house lighting circuit is powered from the inverter when it is on, but from the mains supply otherwise. There is not yet any auto-sense switch on yet though. I did a quick test on a random low energy light bulb and there is no DC path, so need to feed some AC (probably mains) through to enable a current sense circuit.

I've added a couple of screen shots:

	Jan 2nd Charging details
	Monitor display

February 1st 2005 - the first evening of Solar/Battery/Inverter powered house lights. All seems to work, need to check how long it takes to replace the charge in the batteries now.