[RE-wrenches] Voltage Rise

[Dave Tedeyan]

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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