wrote:

Trevor wrote:
Was thinking of getting a solar powered shed light for my Dad. Anyone
recommend any?

Reluctant to buy one that hasn't been recommended after solar garden lights
that dont work.

In line with a lot of toy "solar" powered products that give up the
ghost after a year.

Of course it would really need to work at this time of year to be of any
use, which would I guess mean attaching to a car battery or similar?

I think you need a serious installation, not some pound shop gimmick.
Have a look here for panels and regulators:
http://www.bullnet.co.uk/shops/test/solar.htm

(there are others - they cost a lot. E.G.
http://www.selectsolar.co.uk/kit.php
http://www.windandsun.demon.co.uk/prices_pv_modules.htm)

Then stick in an old car battery and a couple of 12V flouro fittings.
I got mine from an ordinary electrical wholesaler, but the caravan and
camping people have them and so do Maplin.

I reckon this is the least bad option. Although 20Ah gel cells are
easier to carry than car batteries.

You need to do some maths. If you have a 12W tube and use it for 2
hours a day, that's 24watt-hours. A 6W panel illuminated for 6 hours a
day will generate 36watt-hours if the sunlight is bright enough, more
than enough to replace it. In northern climes, a 24W panel may be
needed to replenish the battery in midwinter, but you could always use
a mains charger once a month from December to February.

Trouble is that the average grey skies of winter provide nothing like
the nominal 36W output from the solar cells that full sunshine does. 3W
if you re lucky would be more realistic.

I'd be inclined to recommend a lead acid gel cell about 18Ah, matching
charger and one of the camping type of 12v input fluorescent tube based
lanterns as an alternative. Solar power is really disappointing at out
high latitude and expensive to boot.

Regards,
Martin Brown