solar panel

alan_21_us · #1 07-29-2008

I plan on leaving my boat in the water over the winter, but I will not have electricity past November. What is your thought on getting a solar panel. I have 2 starter batteries and 4 golf cart batteries for the house?

How do I size my requirements? All help is welcome. Any suggestions on Suppliers would also be helpful.

Alan

camaraderie · #2 07-29-2008

Alan...you are fairly far north so have poor sun angles and length of day over the winter so you will need to size up a bit to get decent output. I will assume you have NO usage of electric (i.e. bilge pump does not run daily etc.) and are just interested in compensating for the daily loss of charge in wet cell batteries.
You have about 450 amp hours in your house bank and I will assume a group 27 type battery for your starters and say those are roughtly 180 ah's total for a grand total of 630 amp hours.
Wet batteries typically lose 5% of their amp hours in self discharge per month so you will need to replace only about 35 amp hours per month...or about 2 amps per day ON AVERAGE. Given the bleak winter weather and few sunny days in the northeast...I would look at something that is capable of putting in 5 amps per SUNNY day....which would put you into a 20 watt panel normally...but given your location, perhaps something in the 40 watt range would be better.
I don't think supplier makes much of a difference in this case...the Kyocera and BP panels seem to get good reviews but any hard panel should work fine so shop around. Your mounting for the winter should be ANGLED to face the winter sun rather than laying flat on deck. Hope this is helpful.

Freesail99 · #3 07-29-2008

I may have read this wrong, but a 20 to 40 watt panel would be fine, if he doesn't plan on using his boat or have any other drain on the batteries. A 40 watt solar panel would not re charge his batteries if he went on a night sail, for example.

sailingdog · #4 07-29-2008

The panel sizing that Cam is talking about assumes no major shading problems, decent exposure and positioning and prompt removal of snow.

camaraderie · #5 07-29-2008

Free...I agree...20 watts minimum and 40 watts ideally. Sorry i was not more clear!

Uglydave · #6 07-29-2008

Is it not possible to take the batteries ashore and keep them on a charger there?

chucklesR · #7 07-29-2008

Go with a 40 and it'll even help during the sailing season by getting that last little bit topped off while the boat sits around between sailing days.
Upsize that appropriately if 'on the water' means at a mooring ball and if you have to run anchor lights for safety or bilge pumps due to known conditions of your boat.

My 80w panel tops me off and keeps me there year round all of 50 miles south of you. It's not that 'bleak' I've never used my charger or run my diesel just to charge but my banks are 1/3 yours (210 ah).

alan_21_us · #8 07-29-2008

Thanks to all - I will go and start my internet search for the best value. Installation will be tough, but I think I can get some help. I will go for the 40 amps.

Alan

sailingdog · #9 07-29-2008

Solar panels are usually sized in WATTS... and you want a 40 WATT panel. It will provide about TWO-AND-A-HALF AMPS during the middle of the day, on a sunny summer day.

Quote:

Originally Posted by alan_21_us

Thanks to all - I will go and start my internet search for the best value. Installation will be tough, but I think I can get some help. I will go for the 40 amps.

Alan

eMKay · #10 07-30-2008

I bought a 45 watt panel at WM last month for $80, for installation I set it on top of the sliding hatch, it has rubber feet on it so I jst put it in the cabin while sailing.