Is a 10w solar panel enough

PabloPicasso

PabloPicasso

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Is a 10w solar panel enough to keep a 12v 80ah battery charged over the winter? Boat ashore near Liverpool UK., and as clear a view to the sky as can be had near Liverpool.

Will it need a controller?
If so what type, pmr or mppt?

There will be no draw on the battery as boat ashore and primary switches off.
 
PabloPicasso said:
Is a 10w solar panel enough to keep a 12v 80ah battery charged over the winter? Boat ashore near Liverpool UK., and as clear a view to the sky as can be had near Liverpool.

Will it need a controller?
If so what type, pmr or mppt?

There will be no draw on the battery as boat ashore and primary switches off.
Click to expand...

Depends of type of battery and if you have any parasitic items still connected. Took me a while to track down powered antenna on radio/CD player wired by dealer to always have power (retain station memory). AGM batteries have very low self discharge, just charge then disconnect at posts to be OK over winter. Trojan T105s are at other end of the scale and have pretty high self discharge rate. Fortunately, you don't have this type.

I'm guessing std. leisure type so not a huge charge needed but I'd need to check actual figures.

A 10W panel would probably supply 0.3 - 0.4 Ah/day in Dec./January period which isn't a lot but is still around 0.5% of your battery capacity. I think that would be enough to prevent it running down.

I assume you meant PWM, not PMR. I wouldn't spend extra money on MPPT for such a small panel even though MPPT is a lot better in low light levels when PWM won't reach charging voltage a lot of the time. A lot of cheaper MPPTs are fake and not worth buying anyway.
 
In theory, a 10w will charge your battery, in practice, you will find that it is not adequate. Solar panels vary in quality and many deteriorate rapidly; also, being in Liverpool it doesn't help. I have two different makes of 10w panels; they just about provide a charge in the summer for a few hours to charge car batteries. Location is critical; my 100w panel was keeping my 5 x 120 amp batteries fully charged in the Solent area, now the boat is in south Wales and the solar panel can not provide enough charge to the batteries. As a minimum, you need a 15-watt panel; no need for a controller IMHO.
 
PabloPicasso said:
Is a 10w solar panel enough to keep a 12v 80ah battery charged over the winter? Boat ashore near Liverpool UK., and as clear a view to the sky as can be had near Liverpool.

Will it need a controller?
If so what type, pmr or mppt?

There will be no draw on the battery as boat ashore and primary switches off.
Click to expand...

I agree with Richard except that I would fit a PWM controller

I have a 5 watt panel charging a 60Ah battery no problems ........ actual experience ... not gut feeling !

I dont have a controller but your ratio of "watts to Ah" exceeds the max of 1 watt to 10 Ah ratio that is the usual rule of thumb. I guess that is only relevant in the summer though so no bother if only a temporary arrangement for the winter
 
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My gut feeling (with no figures to back it up) is that 10w is marginal. As prices have come down quite a lot, I'd get 20w and a cheap on line pwm controller (<£10).
 
A 10w panel will be ok during the winter but may overcharge during summer.If you are buying one you may as well get a 20w as there is not a lot of difference in price on ebay also get a controller and you will always have a well charged battery.
 
Kept a boat at Conwy and a 10W panel kept the 110 Ah batt fully charged over winter and even recharged it, slowly, after gentle use.
Again, not relying on 'gut feeling' to offer this advice.
Don't bother with regulators with this setup, croc clips straight onto terminals work fine for this purpose. I have also used the same panel to maintain a
70 Ah car battery in Brittany over the summer months sans problème.
 
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RichardS said:
10W will be fine to keep your battery topped-up against self-discharge provided it has a clear view of the southern sky. No controller required. :)

Richard
Click to expand...

+1. But not if you're going on board and using lights/radio, etc too often. I have 40w and that's just enough to put back what I use in a winter weekend of working by the next weekend.
 
Stemar said:
+1. But not if you're going on board and using lights/radio, etc too often. I have 40w and that's just enough to put back what I use in a winter weekend of working by the next weekend.
Click to expand...

" There will be no draw on the battery " it says in #1
 
PabloPicasso said:
Is a 10w solar panel enough to keep a 12v 80ah battery charged over the winter? Boat ashore near Liverpool UK., and as clear a view to the sky as can be had near Liverpool.

Will it need a controller?
If so what type, pmr or mppt?

There will be no draw on the battery as boat ashore and primary switches off.
Click to expand...

I would have thought so. Certainly a 30W flexible did the job on our 3 x 90AH batteries.

But the best thing is to remove the battery, take it home and use a home trickle charger in the garage.
 
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