i know, there's been millions of posts, they seem to get hijacked and become messy so i thought i'd start this and bookmark it. if i got 100w and need to add more i need a 20w charge controller so best buy with aim to expand? what's the lowest 200 would work on? 15a? i see some kits supply 15a with 200w some 20a... types of panel? mono crystal blah blah..... what's the difference in types? did anyone find a decent supply of a kit or is e bay as good as any? there's a 130w which might do without ever worrying of expansion and having 2 panels on the roof - any good? http://www.ebay.co.uk/itm/130W-Flex...277305?hash=item3ac2524f39:g:DD8AAOSwwpdW7RPN
The different ratings may be because some charge controllers are Maximum Power operating point (MPPT) controllers which efficiently convert the voltage and current from the panels to the 12 to 14.4 volts needed to charge a battery. Other simpler controllers are simply energy dumps to stop you boiling the batteries. These just get hot to waste energy. MPPT controllers search for the optimum current from the panel where the power output is maximum then transform the power to the exactly correct voltage to charge the battery. In these the current out can be more than the current going in if the solar panel voltage is higher than the battery. The clue is in the cost. MPPT controllers have more parts in them. A 200 watt controller will work with a 100 watts panel but really you would need to buy a controller per panel of a type that can be linked together. Then if one panel is doing better than the other or has bird poo on it the two MPPT controllers will work with different adjustments to haul maximim power out of both panels independently. But that is still expensive. PWM controllers waste potential power though by not operating the solar panel at its optimum power output. Beware on eBay the cheap MPPT controllers are actually PWM according to reviews . In a realistic low budget setup connect panels in parallel with diodes in series with each otherwise a shaded panel will drag down a well lit panel. And the shadow of a 5mm rope is enough to stop the solar panel on my boat from working. So can a splat of bird poo.
Thanks @mikedjames, that’s very informative. Is this one a real MPPT? http://www.ebay.co.uk/itm/20A-MPPT-...037274?hash=item3cd64756da:g:za4AAOSwI3RW9i7K
Get a 20a controller as this will allow expansion. Start with 100w and see if you actually need more. Personal the way you use your camper i think solar may be a waste. Unless you are planning more non hook up camping??
I've got a 100w panel & 10A controller kit on order. It should arrive this week. The intention is to use it to use to to keep the leisure battery topped up between trips & to lengthen to time between hookups when oot 'n' aboot. I'll report back on how I get on with it.
