On 17 Dec 2012 at 12:56, IVP wrote:

> Hi all,
>=20
> I have an acquaintance, a menace I've mentioned before, who has
> come up with another way to surprise me
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> He's just installed four 200W solar panels to power his house via
> 24V batteries and an inverter
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> He rang me this morning and asked a question that I wasn't able
> to answer except to say it didn't sound safe. I Googled then and
> now but didn't find any relevant information
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> Apparently the 24V panels he ordered are actually 12V, which
> he's going to sort out with the supplier
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> But in the meantime, he's connecting the panels directly to the
> batteries, bypassing the charger, as he says in full sunlight the panels
> put out 26V which is "enough to keep the batteries topped up"
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> What concerns me is that he says he connects the panels only when
> their output is over 24V and sees a spark. The supplier has suggested
> he not do this, which sounds reasonable to me. 'menace'claims (based
> on what, I don't know) that this spark will do the panel no harm, and
> rang me for reassurance that he is correct. To my mind, a spark when
> a power supply is connected to a load means something is under stress,
> for better or worse, and if they were my panels I'd not be tempting fate
> by blowing an internal connection, thereby getting lumbered with a non-
> returnable damaged panel
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> Am I right to right to advise that panel damage is possible and that
> basically what he's doing is an intuitively stupid thing to do ? (for
> various reasons)

Yes, sounds like a fair call. Taking him at his word that he actually has 4=
 x 12V=20
panels (but intended them to be 24V) and 24V batteries and a correctly spec=
'd 24V=20
solar charger, then a safer interim solution might be to suggest he wire th=
e 12V=20
panels in series pairs to provide 24V and use the solar charger.

--=20
Brent Brown, Electronic Design Solutions
9 Titoki Place, Pukete,
Hamilton 3200, New Zealand
Ph: +64 7 849 0069
Fax: +64 7 849 0071
Cell: +64 27 433 4069
eMail:  brent.brown@clear.net.nz



--=20
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