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Posted by jpeachey on December 17, 2004, 6:24 am
  I am currently using 12V deep cycle battery to power lights and a
radio in an 8x10 shed on the weekends. It would be nice to be able to
leave the battery in the shed instead of bringing it home every weekend.
I am looking at a 5 watt solar panel that is supposed to generate 350
milliamps at 15 volts in full sunlight from Camping world. On the
average I use about half of the battery in a weekend. If I'm getting
about 5 hours of direct sunlight for 5 days will  that be enough to
charge my battery?  Should I leave the panel connected while I am
drawing current from the battery? And last, will it be ok to leave the
battery in the shed and hooked to the panel through the winter if I'm
not going to be there?  Any thoughts would be appreciated

 Thanks, Jeff

Posted by developer on December 17, 2004, 7:29 am

does the panel soldered with a diode?

solar power
 designer and developer from

Posted by Anthony Matonak on December 17, 2004, 9:44 am
 jpeachey wrote:

You don't mention the capacity of the battery. There is a wide range of
"deep cycle" batteries out there. You also don't mention the wattage of
your lights and radio or how long you use them so we can't estimate your
energy requirements either way.

What I can say, a panel rated at 5 watts might produce some 20 Wh/day,
more in the summer and less in the winter. You might expect to get out
of that battery some 16 to 18 Wh/day. If you get 20 Wh/day for 7 days
this comes out to some 112 watt-hours that you can use over the weekend.

Yes, you should leave the panel connected while you draw current. You
can't hurt the panel and you'll need all the power you can get. You
should get a good charge controller, preferably one with a low voltage
disconnect so you don't kill the battery by draining it too much.

I suspect you'll need more than 5 watts. I personally find that a room
that size would only be dimly lit with 5 watts. I would need more like
16 to 20 watts of fluorescent lights to be able to do anything useful.
Assuming another couple of watts for the radio and running for some 4
hours a night this would add up to, say, 160 watt-hours for the weekend.
I would spring for at least 10 watts of PV panels but you might squeak
through with 5 watts depending on what you actually use.


Posted by George Ghio on December 17, 2004, 10:23 am

How many Amp hours is the battery?

Posted by jpeachey on December 17, 2004, 4:37 pm
  Yes, the panel has a diode. I Will be cleaning out the shed for winter
this weekend and will be able to give you info on the battery then. The
radio was taken out of my jeep (no cd or tape in it), I have no idea of
the wattage use. Radio probably runs 5 or 6 hours a day for 2 days. I
didn't get any info with the lights on wattage, is there a way to test
this with a multimeter?

Thanks for the help, Jeff

jpeachey wrote:

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