What?A solar-powered shed (and garden light)
When?Oooh, Summer 2003 or thereabouts
Why?So that I can light up the garden...
How?This project grew from the fact that I had a spare car battery laying around, from a (now disposed of) Ford Escort. Quite a large battery (though barely a fraction of the size of the one in the Jag, that thing's huge), I first made use of it by simply hooking up some 12v spotlight bulbs at either end of the shed, and nailing up a switch next to the door (note: using nails as an electrical fixing is unlikely to comlpy with your local building regulations). This was immediately useful because I could now see stuff in the shed after sunset, which is dead handy when you're trying to put the lawn sprinkler away.
However, this left something to be desired. First of all, I would have to lug the bulky lead-acid cell up to the kitchen every few weeks to top it up, or risk degrading the electrolye. Secondly, the battery was still un-used most of the time, and there was no lighting at the other end of the garden. So, I eventually got round to adding a 14-volt solar panel to the roof of the shed. Solar panels are, by the way, this year's must-have garden fashion accessory - or so I'm trying to convince people. The panel charges the battery via a voltage regulator, which also prevents the battery discharging through the panel in low-light conditions - this is England, after all, so it would be wise to assume it's going to be less than tropically sunny all the time!
Having arranged for a virtually maintenance-free source of energy, it seemed prudent to find something else to do with all that power (ten Watts or so - cor, the power!). I'd been playing with a Luxeon LED emitter for a while, and the two seemed made for each other. So, I ran a length of arctic-grade mains cable (over-engineering? Me?) the length of the garden, and attached the loose end to a transparent box packed full of semiconductor goodness. This budget-luminaire now kicks out about five Watts of ultra-efficient bright white light, any time I need it. Or in fact all the time, so long as it's dark (there's a light sensor built into the box).
- Solar panel