Testing used panels
- Thread starter rich4
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sunshine_eggo
Happy Breffast!
You have to measure it.
So that measures the power of the sunlight. How does that help, other than allowing me to work out the efficiency?
What about isolation faults?
sunshine_eggo
Happy Breffast!
LOL... sorry. I read it as insolation.
Check for voltage from either lead to ground point on panel frame?
No worries. I learned a new word today! Insolation! I thought it was a typo on the amazon ad....
Hedges
I See Electromagnetic Fields!
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HiPot
You also need to check Vmp & Imp. Sometimes Voc and Ioc are good, but power output is greatly reduced.
Or do V(load) & I(load) as I did.
The "proper" way is to buy a PV panel tester, which sweeps the IV curve.
An MPPT charge controller into a less than fully charged battery is another way.
Sunshine's Sunshine tester would also be useful, as sun position and clouds may change during the time it takes you to get through all panels.
diysolarforum.com
You also need to check Vmp & Imp. Sometimes Voc and Ioc are good, but power output is greatly reduced.
Or do V(load) & I(load) as I did.
The "proper" way is to buy a PV panel tester, which sweeps the IV curve.
An MPPT charge controller into a less than fully charged battery is another way.
Sunshine's Sunshine tester would also be useful, as sun position and clouds may change during the time it takes you to get through all panels.
Measuring PV panel performance
I suppose I could buy a solar panel tester like Will reviewed, but that doesn't feel DIY enough to me. Besides, I'm a cheapskate, and I try to do things in the most difficult (and expensive if the equipment wasn't on hand) way. I'm presently working on an underperforming string of Sharp 165W...
diysolarforum.com
Can you do that with an electronic load and a scope?HiPot
You also need to check Vmp & Imp. Sometimes Voc and Ioc are good, but power output is greatly reduced.
Or do V(load) & I(load) as I did.
The "proper" way is to buy a PV panel tester, which sweeps the IV curve.
An MPPT charge controller into a less than fully charged battery is another way.
Sunshine's Sunshine tester would also be useful, as sun position and clouds may change during the time it takes you to get through all panels.
Measuring PV panel performance
I suppose I could buy a solar panel tester like Will reviewed, but that doesn't feel DIY enough to me. Besides, I'm a cheapskate, and I try to do things in the most difficult (and expensive if the equipment wasn't on hand) way. I'm presently working on an underperforming string of Sharp 165W...
Hedges
I See Electromagnetic Fields!
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Electronic load and scope (or DMM, or just reading voltage/current from load) should make a good "curve tracer" to measure PV panel performance. I still don't have an electronic load.
That HiPot test I suggested? If leakage is due to moisture, of course it won't detect leakage except when panels are wet.
That HiPot test I suggested? If leakage is due to moisture, of course it won't detect leakage except when panels are wet.
Vigo
Solar Addict
You can't put a real number to that kind of thing (isolation/insulation) without a 'meg-ohm meter' aka 'megger' which shoots a 500 or 1000v pulse into the circuit and measures current. They aren't cheap enough that the typical solar DIY'er has one.
Measuring dc voltage from PV framing to both sides of the PV circuit would identify any possible issues, but requires you to have the potentially dangerous voltage being 'live' to test for it, and with a lot of installations if there WERE a dangerous PV isolation fault it would be dangerous to even get close to the array without proper PPE to poke said framing with meter leads. But, in real life is it likely to be an issue? Not as far as i've heard.. Without said PPE you would probably be more likely to put yourself in danger from a slipup while testing and making connections with the live PV circuit over and over for as many panels as you have, than the danger you would face from leaving it untested and just not knowing. I'm not against testing for it but the only 'good' way to do it is with equipment most DIY'ers don't have.
Measuring dc voltage from PV framing to both sides of the PV circuit would identify any possible issues, but requires you to have the potentially dangerous voltage being 'live' to test for it, and with a lot of installations if there WERE a dangerous PV isolation fault it would be dangerous to even get close to the array without proper PPE to poke said framing with meter leads. But, in real life is it likely to be an issue? Not as far as i've heard.. Without said PPE you would probably be more likely to put yourself in danger from a slipup while testing and making connections with the live PV circuit over and over for as many panels as you have, than the danger you would face from leaving it untested and just not knowing. I'm not against testing for it but the only 'good' way to do it is with equipment most DIY'ers don't have.
Hedges
I See Electromagnetic Fields!
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Agree, live PV high voltage string with ungrounded frames could be dangerous. Since you can't turn them off, harder to test safely. When not defective, there are safe ways to handle.
Individual panels, voltage may be 60 to 80V, so be careful.
Testing with a HiPot, you connect test leads, push "test" button while not touching device under test.
You could get an old hand-crank megger. Still available new and expensive from Granger:
This is a DIY forum:
The amount of leakage which would cause system malfunction is quite high. Ground-fault circuit is often a 1A fuse. Some older Trina panels reportedly had leakage and were recalled.
Individual panels, voltage may be 60 to 80V, so be careful.
Testing with a HiPot, you connect test leads, push "test" button while not touching device under test.
You could get an old hand-crank megger. Still available new and expensive from Granger:
This is a DIY forum:
The amount of leakage which would cause system malfunction is quite high. Ground-fault circuit is often a 1A fuse. Some older Trina panels reportedly had leakage and were recalled.
sunshine_eggo
Happy Breffast!
Not too expensive (I have this one for some hybrid automotive insulation testing needs):
Vigo
Solar Addict
That is EXCELLENT! I wasn't aware there were any down that cheap!
sunshine_eggo
Happy Breffast!
I recently used it due to an odd issue with some stored PHEV NMC cells. They discharged to random levels - some dangerously low. Out of 588 other cells, NONE had exhibited this behavior. The 21 cells in each module were painfully consistent.
The terminals had been in contact with fiberboard. In a desperate effort to explain what should never have happened, I used the megger to see if the material was even slightly conductive. 1000V showed open circuit.
In the end, I lost 4 out of 21 cells, and I only have high confidence in about 10 of them. Dang cells. Still no clue what actually happened.
TorC
Solar Enthusiast
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Oh, great. Another meter I should buy and own. You guys just love to get people to spend more money, don't you? ; )
Looks like that one is now unavailable. This claims the same model number, though it has a dial instead of all buttons. More or less the same specs and review points: https://www.amazon.com/Digital-Insulation-Resistance-Tester-Megohmmeter/dp/B07BGSPH8P/
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