Small deck lighting system

[Ottawa Clean Energy Nerd]

Hi there - looking to get a small 1-to-3 panel (10 W ea.) system for the roof of my daughter's playhouse to help her get excited about solar (and to provide some power to some LEDs around the yard and deck).

I'm looking to keep a small battery under the deck to store the energy, but I'm just not clear on what type of battery I should or shouldn't use. I'm looking to get a few Enerwatt EWS-10P panels, a PWM 10A charge controller, and looking to run a couple strips of LEDs. Looking online suggests between 0.6 A and 1.2 A per meter, and I'm looking at about about 10 m... so about 12-15 A?

I looked at the solacity site, but the deep cycle batteries (starting at $170) strike me as overkill for such a piddly project. Wondering if indeed they are the best option, or if I could get away with something from Canadian tire or even a small power sonic battery or something.

Any thoughts on battery specs that I should go for would be really appreciated, just want to make sure I'm headed in the right direction.

[Rob Beckers]

Hi Nerd,

Yep, we (as Solacity Inc.) don't really cater to the very tiny systems. The focus is also on more durable components, and for batteries that puts us in the more pricey category.

I'd look for a cheap AGM battery from Walmart or Costco. A 10 Watt panel in full sun facing south will produce around 25 Wh per average day in our general area from spring through fall. Half that in winter. So, 10 Watt of LED lights can run on that amount of energy for 2.5 hours. You'll have to size on the side of caution since there is no generator to pick up the slack for cloudy periods, maybe half that amount in light vs. panel.

On the battery side, a single 10 Watt panel could be paired with a 4 - 6 Ah battery. I wouldn't go any larger than that. The risk of a large battery vs. small PV system is that the battery never sees a full 100% charge and that will kill it in short order. Lead-acid batteries need to see a 100% charge every 2 weeks, especially sealed batteries.

By the way, for a really small system we have a 5Ah lithium-ion battery for $116. Those should be good for 20 years!

-RoB-