Got one of those too... BP 150 Watt 24 volt panel. Feeding 3 12v batteries and running the garden lights. I want to run more off it because the solar panel produces so much power and I am currently using bugger all of the stored energy.
Yeah there is lots of energy coming from there but I'm not sure solar panels are that great either. Certainly not in this country. They have their uses for low power applications and where there is loads of sun (space?!). Problem is they look so hideous and really aren't that efficient so you need a large area of them. I reckon one of the best uses of solar energy is a ground source heat pump. By burying loads of pipe under the surface we are hugely increasing the area over which we can collect heat without having to see a thing. Plus they're pretty damn effiecient. Only problem is, like all these things, they're not cheap.
Solar water is worth it, I think, provided it's not a rip-off price.
I can't see why some (relatively) less well-off mediteranean countries can be festooned with solar water panels when they seem to cost so much in the UK.
Even if you don't get all the hot water from the sun, you can get good pre-heat for the main hot water source.