[RE-wrenches] mechanical vs. electronic kwh meter

Dave Click daveclick at fsec.ucf.edu
Fri Aug 12 08:14:51 PDT 2011


I just asked a guy I know in utility metering, and he confirms that 
there's no basis for the utility's concern. Their claim that backfeeding 
is a safety hazard could be an attempt to dissuade some non-PV folks 
from flipping their meters to steal power. Or that could be their 
justification to charge the customer for the new electronic meter (some 
utilities do this, apparently).

As an anti-theft precaution, some mechanical meters don't actually spin 
backwards- so whether you're importing or exporting a 1kW, after an hour 
your counter has ticked up by one. So just because it's a mechanical 
meter doesn't mean that you should necessary leave it running until the 
utility installs that bidirectional electronic meter.

On 2011/8/12 9:45, Kirk Herander wrote:
> Hello,
>
> I am now in a debate with the metering dept. of a local utility. They
> don’t want a PV system to be energized and tested until a bidirectional
> electronic meter is installed. They insist that an old plain Jane
> mechanical meter can be damaged and is a safety concern if power is
> pushed through it (its running backwards) to the grid. I have never
> heard of, witnessed, or been told this by any utility or AHJ inspector
> until now. Have any of you ever?
>
> I don’t know the reason for their paranoia. I assume that many utility
> districts don’t to this day install bidirectional electronic meters. And
> rely on the original mechanical meter to count backwards reliably and
> safely.
>
> Kirk Herander
>
> VT Solar, LLC
>
> dba Vermont Solar Engineering
>
> NABCEP^TM Certified installer Charter Member
>
> NYSERDA-eligible Installer
>
> VT RE Incentive Program Partner
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>
>
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