solar panel- questions

Submitted: Sunday, Feb 04, 2007 at 10:52
ThreadID: 41953 Views:2976 Replies:4 FollowUps:0
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hi, we are new to the world of solar panels and have just got given an old BP photovoltaic generator, i guessing this is the same as a solar panel. anyway we want to use it to charge up our deep cell battery, so do we need anything in between the solar panel and the battery? We are thinking that we need to get an inverter and plug the panel into that and then our trickle feed charger from that to our battery- is that correct?
the panel is putting out 18.3 volts but we are not sure of what amps it produces, the measurements are 48cm x 45cm
also is the photovoltaic generator just another name for a solar panel or is there some difference?
thanks from gonebush
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Reply By: Leroy - Sunday, Feb 04, 2007 at 11:01

Sunday, Feb 04, 2007 at 11:01
i'll just get into my flame retardant suit first. You could get away with connecting the panel directly to your panel without the need for a regulator as the panel probably is only rated at around 30w so not much chance of over charging. You could, to be safe I supose you could get a cheap solar panel regulator from Jaycar.

Leroy
AnswerID: 219618

Reply By: MEMBER - Darian (SA) - Sunday, Feb 04, 2007 at 17:04

Sunday, Feb 04, 2007 at 17:04
At that size, it might be about 2A output - you could get a quality 5A regulator from Jaycar (about $30) and put that between the panel and your deep cycle battery - no worries from thereon - LED's tell you the status. A budget multimeter can confirm the current for you.
AnswerID: 219698

Reply By: Mainey (WA) - Sunday, Feb 04, 2007 at 19:17

Sunday, Feb 04, 2007 at 19:17
your BP photovoltaic generator is indeed a (small) 'solar panel'

Yes, the 18.3v will eventually harm your 12v battery - if the battery is not under load.

The low amps it produces will not be much use if the battery is under any load, would be good for keeping your battery fully charged WITH a solar regulator.
AnswerID: 219725

Reply By: Steve M - Monday, Feb 05, 2007 at 19:42

Monday, Feb 05, 2007 at 19:42
You can measure the short circuit current by just connecting an ammeter (multimeter) to each wire and bunging it in the sun. This will roughly give you the theoretical output ie as normally stated in panel specs.

From this work out the Ah it will give you per day assuming about 7 solar hours per day ( this is not daylight hours).

Compare this to the load in Ah/day that you will be running off the battery.

If the panel can come close to replacing the energy then get a reg that can handle the load, get a new panel/reg or forget the exercise.

Steve M
AnswerID: 219982

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