solar power

[farquart]

We are off to cruise the Med in May and were considering installing shore power. However since we are intending to avoid marinas as much as possible it doesnt seem worth it. We only need to power minimal lighting, a car cd player and vhf but since we may be at anchor for several days i believe that this is still going to drain the battery. We have a 110ah battery soley for domestics and a Yanmar 3GM engine. Money is an issue and therefore have been looking at a 10w solar panel. Would this be sufficient or would it be just as good to keep a spare battery to swap over & top up with a car charger when in a marina. Also are there any hidden costs, the panel is around £120, do we connet this straight onto the battery?
Please help!!!

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[steve_cronin]

Ten watts

... is around 0.8 amps which at best is only going to replace natural wastage when the boat is out of use. Assuming an optimistic 8 hours of sunshine on a good day this will give you 6.4Ampere hours so it will take a long time to re-charge the battery. Your 3GM probably has the 75 amp alternator. Equipping this with a smart controller like an Adverc or a Sterling would be a better way to spend your £120 as this will ensure that your alternator which is nothing more than a marinised car model designed to just replace what lights, heaters, wipers etc are taking out but with just a little (around 5amps) for charging, properly re-charges your battery up to the full 14.4 volts which mean that it is fully charged up to its full capacity.

To get satisfactory "free" charging you need to look at 50watts at least. This would cost you around £375 for either a solar or a wind generator

We have just bought an Adverc, a BEP charge splitter relay (our batts are 2X140 for domestic and 1X 80 for starting) two 55 watt solar panels and a smart charger for marina hook-ups. To augment these we have a 60watt wind generator from a previous boat. Overkill? Well you should see some of the set-ups on liveaboard boats in the Med! With windlasses, fridges and the odd microwave to eek out the bottled gas not universally available, a good power supply is essential. Twin alternators, IOM the best way of charging separate battery banks, are quite common.

Your best bet is increasing your battery capacity for domestics, getting a second battery for the starter - nothing exotic needed so long as it has the cranking amps rating for your engine, as it doesn't need to deep cycle - and splitting the charge from a controller (battery management system)that will make the best of your alternator's output.

Steve Cronin



<hr width=100% size=1>The above is, like any other post here, only a personal opinion

 

[Richsquest]

Re: Ten watts

I agree, on my boat we have 4 x 110 amp hour domestic batteries, 1 x 110 amp hour cranking battery.
From the domestic batteries we run nav instruments, radar occassionaly, nav lights, interior lights, fridge,occassionally the 1500watt inverter for the microwave, etc,etc,.
To recharge the batteries we have an Aerogen windcharger, two 75 watt solar panels, and an 80 amp alternator which we are modifying with a smart alternator regulator and splitter.



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[AndrewB]

I asked a similar question last week (<A target="_blank" HREF=http://www.ybw.com/cgi-bin/forums/showthreaded.pl?Cat=&Board=pbo&Number=456974>HERE</A>). The answers convinced me a solar panel only makes sense for keeping batteries topped up on an occasionally used yacht, or for one without an inboard engine. You could generate the daily power output of a 10w panel with just a few minutes run on your engine, at little cost.

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[Guest]

For 120 quid ..... you could buy 4 x 5W panels from a car acc. shop .... to top up batterys ......
I use a 5W single to keep my domestic topped up and engine to put in major charge. OK I don't use mine so much as many .... so don't need huge charge amenities !

Surely a 10W can be found cheaper than that though ..... of course the bigger you can afford the better. But as soon as you get up in size (small ones not necessary despite what experts say !!), you need a regulator and reverse blocker.

Now I shall get off the podium and let more knowledgeable people speak ...


<hr width=100% size=1>Nigel ...
So WHAT does the EU really stand for ????/forums/images/icons/cool.gif

 

[pands10]

i have a boat with 120hp diesel + 2 x 85a batteries 1 starter 1 domestic. If i was to add another 85a + link it to my domestic would there be any problems with the alternator charging these or any other problems anyone can think of?

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[Talbot]

Should be no problem at all. IMHO you are very undersupplied for your domestics, I would have expected at least 200 amphrs. If I am using my diesel outboard a lot, it manages to cope with 200amp/hr batteries, (but does need a 6 monthly boost). However the motor only has an 10 amp alternator.

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[charles_reed]

I'd suggest your power allowance is very optimistic.

If you're going to be in the Med during summer you'll need a fridge - at 38C butter runs everywhere and you'll need to shop every day or your food will be "off".

I've been in the Med for the last 3 years and have an Adverc smart regulator with a 100 amp alternator on the 2GM20.
I also have a 100 watt wind generator and an 85 watt solar panel feeding the 300ah battery bank through a two-part regulator.
The pulse charger I have is a 15 amp twin outlet one

The cut outs are set at the following voltages:
Adverc 14.8v with sensing
Pulse charger 13.5v
Wind and solar regulators at 14.4v.

During the summer I spend every 6th night (or so) in a marina - the solar panel and wind generator give me adequate input to put off recharging the batteries until the 6th day.

You'll find the vhf of limited use and I would strongly recommend you have a Navtex for weather forecasts (or a dedicated RTTY receiver).
Your usage will be about the same as mine if I exclude the 50 ah in 24 that the fridge consumes.

rather than buy an inadequate solar panel, I'd suggest a smart regulator will be of far greater value.
You'll have to run the engine to get around during the extended periods of inadequate winds and will need to recharge your batteries during the periods of stormy weather, when your cowering in a marina (there are a limited number of safe anchorages) - it never hits a happy mean in the W Med.

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