Using grid type solar panels to charge batteries.

My neighbour has just picked up 3 x 250w solar panels off a house that feeds back into the grid, because the house owner is fitting a larger system.
My neighbour wants to install a 12v stand alone system on a shed in his back yard, using these panels.
I have solar panels for a 12v system and note that the panel voltage is around 18 - 20 volts. His 250w panels are rated at about 30v. Will these panels work without cooking the batteries? Is it just a matter for the regulator to sort out the differences in the incoming voltages? Like to know what others think.
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Reply By: Frank P (NSW) - Wednesday, Oct 25, 2017 at 19:43

Wednesday, Oct 25, 2017 at 19:43
GerryG,

He MUST have a solar regulator. Without one he will destry his batteries.

He will need a solar reg that can take higher panel voltages than your typical nominal 12V panel. There are plenty available. GSL is an Aussie manufacturer that makes a good product. I have a GSL 30-2 and am very satisfied. The model most likely to be suitable would be the 30-2HV.Link

Of course there are others.

750 watts of solar might be overdoing it for 12V batteries. Give the manufacturer you choose a call.

Cheers
FrankP

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Follow Up By: GerryG - Wednesday, Oct 25, 2017 at 20:47

Wednesday, Oct 25, 2017 at 20:47
Thanks frank,
I did mentioned the regulator in my blog as I know he will need one. I just didn't know if there was a reg. that would tolerate the higher voltage but you've given me some good leads.
750w is a bit excessive but he got them for $50 each. The site is a bit shady so I suggested he put up two panels facing North and the third, if he thought he needed it, facing the evening sun.
To be honest with you, I'm thinking, at $50 each, I might get a couple myself. Just needed to know if there was a reg. that would absorb/tolerate the higher volts.
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Follow Up By: Bob Y. - Qld - Wednesday, Oct 25, 2017 at 23:15

Wednesday, Oct 25, 2017 at 23:15
He needs a reg like a Victron 75/15, or they have other models too, for the higher voltage panels.

Bob

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Can't remember most of it.

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Follow Up By: Frank P (NSW) - Thursday, Oct 26, 2017 at 00:15

Thursday, Oct 26, 2017 at 00:15
Bob,

Yes, Victrons are good. The one I mentioned will charge 12V batteries from solar panels up to 160V OC.

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FrankP

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Reply By: COLIN / LESLEY VK3ZZS - Thursday, Oct 26, 2017 at 10:16

Thursday, Oct 26, 2017 at 10:16
safe to use as long as you use a regulator of suitable wattage.

best of sunny days to you

colin mobile tassie
AnswerID: 614594

Reply By: RMD - Thursday, Oct 26, 2017 at 11:05

Thursday, Oct 26, 2017 at 11:05
Because the panel OC voltage is far above the normal panel voltage you will need a regulator able to handle that input voltage.
If the regulator you choose is an MPPT regulator, in this case it can take advantage of the additional voltage and combined with the amp flow availabe it will convert the energy available, ie volts and amps which is wattage, into more charge into the batteries than a normal Pulse type regulator is able to do.
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Follow Up By: qldcamper - Saturday, Oct 28, 2017 at 10:19

Saturday, Oct 28, 2017 at 10:19
That combination works better than I expected, I have installed a 180 watt 36 volt panel on the lid of my trailer coupled to a victron 75/15 and on a heavily overcast day it still puts 0.6 amps into the system.
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Reply By: Banjo (WA) - Friday, Oct 27, 2017 at 08:47

Friday, Oct 27, 2017 at 08:47
and due to the higher voltage you can use smaller wiring.
AnswerID: 614616

Follow Up By: Zippo - Friday, Oct 27, 2017 at 14:58

Friday, Oct 27, 2017 at 14:58
and rated for the panel peak voltage, NOT typical 12V stuff (the cheaper end of which would be dubious at 30V).
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