Solar panels on or off in winter?

[Caboteur]

Expert advice...
I have 2 X 85W solar panel bank that I leave on all summer. They are linked to the battery bank through a supposedly smart controller.
The boat is on the hard for the winter, it is a little north of 45°N. The sun will therefore not be any higher than 30° for the next three months.
With such little exposure should I leave the panel "on" and trickle charge the battery bank or should I turn all this off?
Just for fun... at 45°N we have ice bridges over our summer cruising area!
What do you see as the pro's & con's?
Thanks
Pierre

 

[Steve W]

I'd just leave them on, where they are. The cold weather and snow shouldn't bother them. The only thing I can think of is that you might want to brush off all the snow after a storm. Not because the snow moisture will harm them (they get soaked in a squall or rainstorm during the summer) but repeated freezing and thawing ____might___ cause moisture to work it's way into a crack and that freeze/thaw cycle could cause it to get worse. If you don't need them to function as a trickle charge over the winter then just throw a tarp or cover over them.

 

[Maine Sail]

Pierre,

Consider the potential for snow cover on the panels, the phantom/parasitic loads your boat has, the parasitic load of the solar controller and then wonder if the panels can keep up when buried under 12" of snow while you have a 0.2A - 0.8A draw from things like LPG sniffers, bilge switches, the controller, stereo memory, combiners, Echo Chargers etc. etc.. With the winter sun angles "catching up" may be hard even for 170W of solar unless the panels are strategically aligned to the sun angle.. If, like most boats, your panels won't be angled towards the best sun angle. Ours is disconnected and we're in Maine, a little South of you..

I personally prefer to 100% disconnect the bank, by disconnecting the ground wire. I only do this after fully charging the banks. It never hurts to charge & top them up a few times throughout the winter to prevent electrolyte stratification, if wet cells.. In a perfect world I would leave the solar connected but in the great white North it's rarely a "perfect world" when winter hits..

I would try an experiment and see how much they put out in peak sun and also test your parasitic loads to see how much they will play into it..

Just one week of snow covered panels with a 0.5A parasitic draw = - 84 Ah's

Even a 0.2A parasitic draw puts you at a 33 Ah deficit per week....

0.2A X 24 X 7 = -33Ah


Food for thought..

 

[Night Sailor]

I assume from your post that your panels are mounted flat and can't be tilted toward the sun. I leave my on all the time, but change the angle of incidence ralative to the sun's average postion.We don't get a lot of snow here in TX but I have my panels on pivots made from railing parts, and the tilt keeps them at an optimum angle for power, and the snow slides off when it gets more than six inches deep. They do produce power when covered with six inches of snow and keep my banks charged all winter..