[RE-wrenches] Voltage Rise

[Jerry Shafer]

Wrenches, Dave
I have had this issue, first turn off everything, check static voltage,
this will drive everything else. If the static is 240 L-L look at the
utility side you might have small conductors, you might also have a
transformer size issue bottlenecking the current.  Next turn loads more the
better watch if there is a drop and how much. Now turn off everything and
power up the solar again watch the voltage at the meter if it climbs up and
close to limit it might be the feeders. It's all process of elimination.
Lots of fun


On Thu, Feb 23, 2023, 9:03 AM Dave Tedeyan via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Hi All,
>
> I've got a customer who is having issues with high voltage at their house.
> This first became an issue after installing 23.1kw of AC solar output. They
> have some GREE heat pumps which have been having some failures. The heat
> pump people are saying that the problem is that the voltage is above 252V.
>
> The grid voltage was measured at 246V with the solar off, and 260V with
> the solar cranking. The inverters are within 10' of the MSP where there is
> a line side connection. Then there is 4/0 AL cable which has to go roughly
> 175' before it reaches the transformer. At 246V and 92A, there should only
> be about a 3.6V rise, or maybe 4V including the wire from the inverters to
> the combiner to the MSP. Yet somehow there is about 14V of rise.
>
> The service entrance cable is buried. It is in conduit where it goes into
> and out of the ground, but I have no idea whether there is conduit for most
> of the run underground. Maybe there is a nick in the cable underground
> which has caused corrosion? Does anyone have any ideas of how to find the
> cause of the increased resistance? I should go back out there with an IR
> camera to check the connections that I can at least get to in the house.
>
> I have suggested that they install a buck/boost transformer on the heat
> pump circuits to bring down the voltage a little bit. But they are also
> concerned about the high voltage causing issues with other electrical
> appliances in the house. Does anyone have any anecdata to show whether
> there are other hidden issues if the house is at 260V during times of high
> solar production?
>
> Thanks!
> -Dave
>
> --
> [image: Logo] <https://www.sungineersolar.com/>
> Dave Tedeyan, P.E.
> Owner | Sungineer Solar
> p: he | him | his
> a: 1653 Slaterville Rd. | Ithaca, NY 14850
> w: www.sungineersolar.com <http://www.sungineersolar.com/>
> c: (607) 288-2898
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