Solar pump

[Aukai]

I know next to 0 about electrical testing. My solar water heater pump motor(24V) is not running, with the pump disconected my late afternoon voltage is 18.7 VDC from the panels. When I connect the pump back up, I only get a minimal reading of .01 VDC, with one wire disconnected I get the 18VDC again. Continuity gets a tone, and the Ohms reading is 4 ohms from the motor wires disconnected from the panel. What am I looking at here? Thank you

 

[woodchucker]

sounds like it is shorted out, but I am no expert.

 

[SLK001]

Your panel(s) are (probably) bad. 18.7VDC in full sun from a 24V+ panel is a bad sign. Go look at your panels and look for cracks.

 

[Aukai]

I will get up on the roof tomorrow to check on the panel, and recheck the voltage during better sun angles. The pump motor has a 2018 date on it which I didn't think is too bad.

 

[Aukai]

I klunked the motor with a wrench(like hitting a starter), and it ran till some clouds came buy, and it won't run again. I still have to get up on the roof.

 

[WobblyHand]

I klunked the motor with a wrench(like hitting a starter), and it ran till some clouds came buy, and it won't run again. I still have to get up on the roof.

What's your mid day voltage from your panel? If it's low, your motor will need more current. But having to clank it sounds like it's gunked up, the bearings are going or gone, or maybe there's an issue with the impeller.

 

[Aukai]

11:00 AM voltage is 19.7, with the motor wires connected it drops to decimal point voltage. I checked the panel on the roof, and it seems to be in good condition visually. The wire connections are tucked up tight, and sealed under the panel, so I did not check them.

 

[WobblyHand]

11:00 AM voltage is 19.7, with the motor wires connected it drops to decimal point voltage. I checked the panel on the roof, and it seems to be in good condition visually. The wire connections are tucked up tight, and sealed under the panel, so I did not check them.

I don't know much about these panels but that voltage reading sounds low, especially if the motor states it's 24V. I'd expect a higher voltage than 19.7V on a clear day close to noon. Could be hidden corrosion in the wiring connectors, or a dying panel. I'd be checking the wiring and inspecting the wire connections. If they are good, then it might be the panel. Betting it's corrosion, due to your location.

 

[WobblyHand]

The back of the panel should have a VOC rating on it. What is it for your panel? VOC stands for Voltage open circuit.

 

[WobblyHand]

A 100W monocrystaline panel has a VOC around 21.3V, according to the googles.