the other benefit of having a panel is that if the worse comes to the worse and your main battery drains for some reason in the middle of nowhere you have a method of recharging it.
while a solar panel will provide adequate charge for lighting on it's own, as above, it won't be adequate for powering bigger items. to calculate what you have and what you need look at the current draw in amp hours of the equipment you will be using. then look at the AH of your proposed leisure battery and see if it will maintain those items for as long as you are likely to need them (say overnight for a fridge) you then need to consider the output of your panels during both optimum and shade conditions and see if that will provide adequate charge. If necesary, if you have space and weight available you may need to connect two batteries to give the Ah you need.
You will also need a charge controler or you will potentially fry your battery, although you may be ok on a small set up.
Personally I would go for a split charge system for when the vehicle is running (as described above) with a facility to plug a solar panel into the fag lighter (or simlar suitable connection) when you are parked up to top up. make sure though that the wiring is man enough for the job (i.e can handle the output of the accessories and the leccie produced by the panels).
my expertise is on solar systems in buildings, not vehicles, but this is a complex business. there are a number of good books on the subject though. I would recommend 'solar electricity handbook' by michael boxwell.
maplins, amongst others do suitable kits.
on the subject of fuses. the idea is not to fit a fuse so big it won't blow, it's to fit a fuse that will blow before your wiring melts! make sure the fuse is suitable (i.e. rated lower) than the capacity of your wiring, otherwise you'll have an impromtu barbeque on your hands.
the fuse doesn't help in the event of a short in the panel or it's wiring as the fault current is only marginally higher than the DC operating current. it's there in the event of overload or fault in your accessories. we don't even fit fuses on the dc side of domestic systems generating kW of power. they are only fitted on the AC side to protect the wiring from the demand side.
do check the output of what you buy. if you get a panel for charging a mobile you will have died of old age by the time it charges your battery!!
hope that helps
Sparking Moggy Solar
Dorset Solar Photovoltaic Energy UK | Dorset Solar Power
1990 Landcruiser H60. Full rebuild completed 2014
2012 Hilux, mountain top and bedrug with GG AT2s
Last edited by moggy 1968; 2 Jan 2011 at 23:03.