What size solar panel

[Tony]

I'm thinking of adding a solar panel to keep my battery charged up. I only use it to power nav. lights and the cabin lights for occasional overnights. I'm looking at the flexible unisolar panels since they seem to be easy to place on the boat. What size should I use to keep my battery topped up - 11W or 5W? Tony

 

[Miles]

I've got the Unisolar...

32 watt and it does a good job of charging up my 4D house batteries as long as I'm not running the refridgerator. A lot depends on how big your batteries are, also you really can't get TOO much power. A guy on my dock has a USF 5 watt and says it does a good job of keeping his battery topped off but doesn't actually charge it up much if it's discharged. I'd say go with the 11 watt if not the 32. The best prices I've found by far are at Solar Electric Inc. (about half of what WM wants...) Some of them are cosmetic "blems" but I couldn't see anything. I put the link below, love that new feature!

 

[Frank]

I've got the 11 watt one.

I have an 11 watt unisolar and don't have any worries so far.

 

[Bryan C.]

11W probably ok

Unless you hook it up to your regulator, you want your solar power to be no more than about 1% of your batteries amp hour capacity. An 11w solar panel puts out about 11/15v ~2/3 of an amp, so if you house amp is bigger than 70 amp hours you should be ok.Make sure the lead connected to the positive post on the batter is fused.

 

[Bryan C.]

Correction

My post should have read "Unless you hook it to a voltage regulator..."

 

[GT Lowden]

11W

It sounds like you have a similar electrical requirement as I do. Although the 5w would keep up with a minimal electrical need....I went with the 11w just in case something gets added in the future.No more lugging the battery out to charge!!! yee haa!G.T. LowdenSV Serenity

 

[Wanderer138]

Minimum 11W

The rated wattage is for ideal sunshine conditions, under which you will get about 0.9A. You would also have to move the panel every so often to keep it perpendicular to the sun.With the panel fixed on your boat, you might get about half of that, or about 5 amp-hr for 12 hours of daylight. This should be enough restore the power you use each time if you sail two or three times a month and allow enough time between uses to let the panel work its magic.I have a 10W Unisolar panel on my H23 and it works great. I use a tiller pilot and sail at night. If I do need to recharge quickly, I take the battery home and put it on the charger.PeterS/V Raven