Solar panels for battery charging (boat, caravan, etc.) where to find good information?

I'm looking into solar panels for maintaining (and on good days charging) the batteries on our boat.
Where can I find good unbiased information about the relative advantages and costs of different types?
Basic questions are:-
What technology to go with? What *actual* output can I expect for a given nominal wattage (in France but not very far South)? Are flexible (walkable on) panels any good? .... etc.
I will do the installation/wiring etc. myself, will probably buy the electronics separately from the panels, advice on this side of things (i.e. where to buy etc.) would also be welcome.
The boat is 12 metres long so has a reasonable amount of roof, though not in one big chunk. The batteries are three 12v 200Ah, two for 'leisure' and one for starter.
--
Chris Green

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snipped-for-privacy@isbd.co.uk wrote:

annualised average is about 4.7kWh per day pert square meter in France.
In winter one quarter of that, in summer four times times that.
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So that's 200 watt hours in a day from a 60 watt panel, 200/24 watt hours per hour, i.e. it averages somewhat less than 10 watts during the summer. About three times less in winter.
Thanks, it at least gives me some 'real' figures to work from.
--
Chris Green

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On 12/06/2012 12:26, snipped-for-privacy@isbd.co.uk wrote:

This isn't from experience, just what I've seen - but have you considered a little windmill?
Andy
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On Tue, 12 Jun 2012 12:26:52 +0100, snipped-for-privacy@isbd.co.uk wrote:

I can't supply you with much info, but I can say from experience that even the cheaper polycrystalline 15W panel will keep a 70Ah battery topped up over winter. I bought one five years ago, just after buying a new battery and then laid the car up for nearly four years. The battery survived just fine during that time and what killed it was the vicious cold weather and a dud alternator the following winter, after nearly a year of being back in service. If it hadn't been for that I'd probably still be using that battery. Charging rates ranged from 600mA summer to 120mA winter. It was enough. I never measured it giving its max, which would have been a nominal 1.2A, but I took that with a pinch of salt anyway. Perhaps I might have seen that on a more discharged battery on a high-summer day, but I doubt it.
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Grimly Curmudgeon wrote:

You just have to make sure there's no drain on the battery from vehicle electronics.
Bill
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wrote:

20 year old diesel - no drain from any of that new-fangled nonsense. That's why I keep it. Oh, it has a digital clock, which goes into standby with the ign off. The only other thing that's been added is a decent car audio head unit, which will have a slight standby drain.
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http://www.machinemart.co.uk/shop/product/details/interplex-solar-2-go-5-watt-poly-crystalline-s
Pro-rata that's very expensive, bigger panels are moving down towards £1 per watt of output now. The above kit includes a battery of course (which I don't want) and the charger (which I do) but I feel that shopping around for the individual bits will get me a better deal and probably better 'bits' (though they have to be correctly matched of course).
Looking further at Machine Mart even their Solar Panels by themselves are expensive, e.g.:- http://www.machinemart.co.uk/shop/product/details/interplex-solar-50-watt-mono-crystalline-solar
That's £298 for a 50 watt panel, way more than can be found on eBay and elsewhere.
--
Chris Green

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On Tuesday, June 12, 2012 7:26:52 AM UTC-4, (unknown) wrote:

http://www.facebook.com/pages/Solar-Wind-Projects-Home/268488803203806
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