Nigel M wrote:

Sorry, I should have said. This is a stable, so enough to see the horse!
I was thinking of around 40W of tungsten, so I think an 8W fluorescent
tube would be ideal.

All our stables have a pair of 13W CFs each. This is plenty.

Don't use tungsten - waste of energy.


But where to get one to run from 12V, what size battery, how to
re-charge, and what sort of cable and switching?

Ok, you need a light, like this:
http://maplin.co.uk/Module.aspx?ModuleNo=22907&TabID=1&source=15&World ID=&doy=13m10

Then you need a car battery. They are well suited to this type of
application, where they don't get fully discharged. Local scrap yard is
a good place for second hand ones (£5 each), or any motor factor.

Then you need a solar panel. A weatherproof one is a good idea, and if
it doesn't have a diode built in, you need to add one. Tjis one is ideal:

http://maplin.co.uk/Module.aspx?ModuleNo=2317&TabID=1&source=15&WorldI D=&doy=13m10


Then you need some cable and a suitable switch. I'll leave those for you
to figure out ;-)


--
Grunff