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Forum Index : Solar : Best way to load cheap panel.

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Phil23
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Joined: 27/03/2016
Location: Australia
Posts: 1667

Posted: 11:40pm 07 Dec 2019

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Hi All,

What I'm looking for is a very simple way to load a cheap panel from a solar garden light to simulate a pyranometer, very roughly.

It's part of the micro that runs my solar Spa heater.

Previously I just had a panel robbed from an old light with circa 10 ohms across it & measured the output voltage on an analogue pin on the Micro.

600mV was my cut in point & 250mV the dropout point.

Max output I'd see during the day was a bit above the 2V mark.

That panel has died & the ones I've tried so far won't work with the 10 ohm load.

So before I go further working out what values will work with whatever panel I find.
(latest will be a new $4 Bunnings solar light).

I know just measuring the voltage across a load resistor is pretty rough, but not sure how I could measure both the voltage & current, due to current being small & anything I'd measure across a shunt would be near minimal.

Any simple better solutions of is the single load just good enough inline with keeping it simple.

Phil.

Phil23
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Joined: 27/03/2016
Location: Australia
Posts: 1667

Posted: 12:04am 08 Dec 2019

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Just pulled the Donor light apart.

3 white Led's 1.2V AA NiCad & an LX805 Solar Charge controller chip.

Wondering if that chip is of any use in an imploved solution to my system.

https://www.google.com.au/search?q=yx805+ic+datasheet&tbm=isch&sxsrf=ACYBGNS2e0GUKUlZeZRTl_K-hL5wSZhtow:1575763259740&source=lnms&sa=X&ved=0ahUKEwjyguPK36TmAhV0xzgGHalRC2gQ_AUICigB&biw=1536&bih=690&dpr=1.25#imgrc=_&spf=1575763264095

Phil.

Phil23
Guru

Joined: 27/03/2016
Location: Australia
Posts: 1667

Posted: 01:59am 08 Dec 2019

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Only other data I now have is that the panel outputs a VOC of around 2.5V
ISC, I measured at 90 & 95mA on the 10A & 400mA ranges of my meter.

And it's a bit dull here today due to the smoke haze.

Load resistor I had previously turned out to be 27ohm's not 10 as stated above.

Cheers.

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