Posted: 7/18/2012 3:42:25 PM EDT
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I'd like to dip my toe into the ability to charge batteries with solar. Right now I have two 33mH batteries connected in parallel that I trickle charge with a Battery Tender Jr every so often. I only use them for emergency power, not everyday use. Pretend I know nothing :) and please recommend some simple panels for me. I haven't even really seen any before, so what is the typical terminal from the panels? Straight to the batteries? Or to an outlet that the trickle charger plugs into?
Also, what would I need to charge four Eneloop AA batteries in the same or separate system? I'm thinking I could leave something small under our bathroom skylight to charge the AAs at will. Thanks. |
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put a charge controller between the panel and batteries to protect the battery and prevent discharge. a 20wt panel is roughly 1.6a at peak output. for a 33ah battery it would take roughly 20hrs to charge from complete drain. about 10h at 50% this is peak output, remember you will likely only get 4-5h a day of peak on full sun. over cast days will be less.
the bigger the panel the more forgiving in off peak conditions. using my chargers during the tornadoes here last year i found anything "needed" that needs more than one 4-5h session to charge becomes a PIA to deal with and a bit frustrating. ALWAYS buy more panel than you need JMHO but figure your need and double it. |
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Northern Arizona wind and sun––––––––> solar Panels––––––––->Kyocera solar panels they are the best
http://www.solar-electric.com/kykd140wa12v.html |
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Welcome!
First, while you could in theory hook panels directly to your battery, in the long run, bad things can happen as this is unregulated charging and there is nothing to do the electrical things that SLA batteries like having done to them. First, some advice. If possible, leave your current batteries connected to the Battery Tender at all times. It's called a Tender, not Charger. This will help to ensure longevity and readiness. Now back to solar. There are two types of charge controllers. There are just standard charge controllers which pull the solar panel battery down to whatever voltage is being applied to the battery for that particular state of charge. This is fine as far as the battery is concerned, but it is not the most efficient use of your panels. Some of the better brands of charge controller are Morningstar and Steca The other (and more $$$) type is Maximum Power Point Tracking charge controllers. These charge controllers isolate your panel voltage from your charging voltage. They "load" the panels at various voltages while monitoring current draw to determine the point where power output is maximum (hence MPPT). This results in more power going in to your battery (effectively, a higher current on the charger side). For more info, please Google. Now, as far as panels are concerned, you generally have two types. Monocrystaline and Polycrystaline. Mono panels are made from one large continuous piece of cell material. These tend to be the most expensive but they have the benefit of being smaller / watt (less surface area compared to other chemistries), are slightly more efficient (18-22% mono vs 12-18% poly), and the perform better under heat (as panels heat up, they lose efficiency, mono panels are better here than poly). Panels will have all kinds of connection options, but you can always strip down to bare wires and connect whatever you want. In general, to charge your batteries, you want to go Solar Panels ––> Charge Controller ––> Batteries. As far as charging AAs... I HIGHLY recommend you purchase a Goal Zero Guide 10 Plus Adventure Kit which includes a 4 AA/AAA charger that doubles as a flashlight and a USB power source and a 7 watt foldable solar panel. Here is a video of a complete portable solar generator I built. Feel free to ask more questions. I would post more, but have to get to bed! 
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