[RE-wrenches] Shading from Overhead Transmission Lines

[Rebekah Hren]

Hey Jerry,
If I remember correctly - it was about five years ago -   it was a little
complicated because the utility was doing the witness test where they pull
one phase and leave the other two connected, then test that there is no
current on any phase (because the inverters should shut off when one phase
drops). So two phases were still fully connected to the utility power, and
there was current flowing on those conductors, not from the PV array but
induced from the higher voltage lines. The inverter did shut off, but the
utility was still measuring over 1A  (at 12.47kV). I don't think we would
have noticed except that the utility was specifically looking for the lack
of current on the lines at that moment. I don't know what the high voltage
lines were, maybe 100 kV and not that far above the PV system lines?


On Wed, Feb 24, 2016 at 6:08 PM, Jerry Shafer <jerrysgarage01 at gmail.com>
wrote:

> Just so l understand you had current not voltage where was the current
> flowing to.
> I have had static voltage from HV transmission lines but not induced
> current while the system was off.
> Jerry
> Jerry
> On Feb 24, 2016 12:42 PM, "Rebekah Hren" <rebekah.hren at gmail.com> wrote:
>
>> I'd be more worried about  induced current/voltage on metal/conductors in
>> the PV array, which seems like it could cause issues with GFP devices, and
>> possibly unsafe conditions. I worked on one large array (5 MW) where the
>> point of interconnection was parallel to / under high voltage lines. Even
>> when the PV system wasn't operating there was measurable current on the PV
>> system conductors induced from the high voltage lines above. The utility
>> nearly wouldn't let the system be allowed to interconnect, because we had
>> trouble proving the anti-islanding was working as current was still flowing
>> when the utility supply was disconnected (on the lower voltage not higher
>> voltage lines).
>> Rebekah
>>
>>
>> On Wed, Feb 24, 2016 at 4:18 PM, Jerry Shafer <jerrysgarage01 at gmail.com>
>> wrote:
>>
>>> We have both GT and off grid in the shadow lines, because of the
>>> distance away, diameter of the wire and also the sun have not seen any
>>> issues that will warrent micro inverters. All that said, its a moving
>>> target and if the wires are very close then it will be more of an issue.
>>> Something else to ponder can you in fact install under HV transmission
>>> lines in your area.
>>> Jerry
>>> On Feb 24, 2016 5:50 AM, "Paul Lyons" <Lyons at zapotecenergy.com> wrote:
>>>
>>>> Hell RE-Wrenches –
>>>>
>>>>
>>>>
>>>> Do any of you have experience with locating ground-mounted PV systems
>>>> under high-voltage transmission lines? We have an electric utility client
>>>> who would like to use some of its land underneath its HV transmission lines
>>>> to install PV. Is the shadow cast be the overhead wires significant enough
>>>> to affect the string voltages in the array? Should we go with
>>>> micro-inverters?
>>>>
>>>>
>>>>
>>>> Thank you,
>>>>
>>>>
>>>>
>>>> Paul Lyons, P.E.
>>>>
>>>> Zapotec Energy Inc.
>>>>
>>>> 675 Massachusetts Ave
>>>>
>>>> Cambridge, MA 02139-3309
>>>>
>>>> Tel: 617-547-5900  ext.201
>>>>
>>>> Email: Lyons at ZapotecEnergy.com
>>>>
>>>> Web: www.ZapotecEnergy.com
>>>>
>>>>
>>>>
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>>
>> --
>> Tel: 336.266.8800
>> NABCEP Certified Solar PV Installation Professional™ 091209-85
>> NC Licensed Electrical Contractor
>>
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-- 
Tel: 336.266.8800
NABCEP Certified Solar PV Installation Professional™ 091209-85
NC Licensed Electrical Contractor
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