Carl Gibbs wrote:

"Albert T Cone" wrote in message
...
Putting it behind glass (e.g. inside the car) also removes the UV,
which is a good thing from a skin health point of view, but is also
the region of the spectrum containing the high energy photons from
which a god fraction of the energy you net comes from.

It'd be mounted outside so no problem there
Fair enough, but then you have to worry about the thing being properly
weather-sealed. Also (and this probably isn't really a concern for you)
you get UV-degradation of the silicon in the panel, giving a gradual
degradation of performance over several years; this is one of the main
reasons that photelectric cells basically never pay for themselves.

Furthermore, as Steve F mentioned, the silicon panel itself, in the
absence of light, will actually drain the battery slightly (the better
ones have the diodes to prevent this); if the weather is against you,
then it is quite definitely possible for the nighttime drain to exceed
the daytime charge, and leave you worse of than you are without it!

If I were you, I'd fit a battery isolator switch somewhere inconspicuous.

Entrance to the car is via electronic solenoid though. Plus I wouldn't
be able to switch the alarm on which means invalidated insurance.
Ah, forgot about the funky door button thing. How do you get in with a
flattery? An external 12V jack? You could always fit a builders van
style hasp and padlock to the door...

I need to think about this a bit more I think. And check what the
actual current drain is.
Aye, good plan. I might also look at getting a deep cycle battery,
possibly someting like the optima things that Burgerman used to flog.
It'll still discharge, of course, but it won't lose capacity as quickly
as a result, and the v.low internal resistance means that it'll still
start the car even when damn near empty. I don't think they're cheap, mind.