High Voltage on L1

[davedottcom]

Customer of mine gave me a call. (I did not install this particular 10KW PV system)

He says when his PV system produces the full 10KW output, it raises his voltage on LINE-1 from 120-ish to 132-ish. (L1 to ground)

The only reason he even noticed it was because his RV was plugged in at the time and he has some kind of Factory installed Surge-Protection on his RV. It would shut off and give him an error code stating the voltage on Line-1 was too high. He used to think it was the RV but he recently purchased a new RV and it does the same thing.

He has already had the POCO out there and supposedly they have changed the transformer and made some adjustments??? (Not exactly sure what that means!)

He has had the solar pv installer out there and they said everything was fine on their end.

The ONLY thing I could think of was to swap L1 & L2 on the pv inverter breaker and see if that makes any difference!?!?

He did this and is going to let me know if it happens again and if it is still on L1 or if it is now on L2.

Any thoughts?

 

[GoldDigger]

Customer of mine gave me a call. (I did not install this particular 10KW PV system)

He says when his PV system produces the full 10KW output, it raises his voltage on LINE-1 from 120-ish to 132-ish. (L1 to ground)

The only reason he even noticed it was because his RV was plugged in at the time and he has some kind of Factory installed Surge-Protection on his RV. It would shut off and give him an error code stating the voltage on Line-1 was too high. He used to think it was the RV but he recently purchased a new RV and it does the same thing.

He has already had the POCO out there and supposedly they have changed the transformer and made some adjustments??? (Not exactly sure what that means!)

He has had the solar pv installer out there and they said everything was fine on their end.

The ONLY thing I could think of was to swap L1 & L2 on the pv inverter breaker and see if that makes any difference!?!?

He did this and is going to let me know if it happens again and if it is still on L1 or if it is now on L2.

Any thoughts?

Is the inverter connected from L1 to L2 rather then actually delivering power L1 to neutral and L2 to neutral?
If so, then the most logical explanation is that there is a higher resistance in the L1 connection than in the L2 connection somewhere between the inverter and the POCO transformer, or that one side of the center tap in the POCO transformer has a higher resistance.

The inverter will let the voltage rise to the point that the reverse current flow can push all of its output power back to your loads and/or POCO.

If you can put an equally high current single phase load on the system and get a voltage drop from 120 to 108, then it is a problem in your service or feeder wiring or in POCO. If that load does not cause a large voltage drop, the problem is in the wiring closer to the inverter. I do not know of any fault in the inverter itself that could cause this symptom.

 

[davedottcom]

Thanks!

Since this only happens every once in a while (weather permitting) he will be letting me know if it ever happens again.

I have no idea if the inverter is feeding L1-neutral or L1 to L2. I did not install it, never saw it, and I don't even know what brand it is.

I haven't seen an inverter in years that was not L1 to Neutral & L2 to Neutral as apposed to L1-L2. But I guess there are plenty of them out there.

Hmmm, to create an equal load would mean 5,000 watts on L1 only... I could hook-up a bunch of 1,500W space heaters on L1 and take some voltage readings.

It's probably a loose connection in the overhead service... that's my guess anyway.

Thanks again.

 

[BillK-AZ]

More information on the PV system will help get you some answers.

• Model of inverter and any menu/jumper configurations (it is possible to configure some inverters to operate without a neutral, then if L2 is low, L1 will be high)
• Wiring to the inverter, gauge, run length, number of wires (neutral?)
• Voltages on L2 and L1 to Neutral and L1 to L2
• Does the inverter often trip out for overvoltage?

 

[ggunn]

When this is happening turn off the inverter and measure L1 and L2 voltages. If L1 is significantly lower than L2 the issue may be voltage drop on the L1 side from the service/transformer. Voltage drop becomes voltage rise when power is being supplied from the other end of a line.