There are really 3 kinds of meters in terms of running backwards and
billing.
1 True mechanical - these run and read forwards and backwards and are
not only safe to run backwards but they will inherently bill that way
too as there is not way for the utility to know whether they ran forward
or backwards.
2. Mechanical disk with magnetic sensor spot and pick-up. These look
mechanical from the outside - spinning disk - turning numbers - but
they've been retrofitted with a magneitc spot and a pick up that counts
everytime it goes by. These will run the wheell backwards but the
pickup doesn't know which way it's going and just counts magnetic
passes as revolutions no matter which way the disk is spinning - hence
you get billed forward even if it runs backward.
3. True electronic - which totally depend on software to read the
signals in terms of billing.
On the mechanical meters you can see whether it has the magnetic sensor
inside or not.
Hope that helps.
Jeff
Dana wrote:
Another issue is with our local mechanical meters is no
matter which way they run they are adding KWHR so to leave
it running you are costing your customer $ not saving them
$. We test to see that is does back feed for 5 minutes and
then turn it off till the net meter is installed.
Dana Orzel
Great Solar Works, Inc
E [email protected]
V - 970.626.5253
F - 970.626.4140
C - 970.209.4076
web -www.solarwork.com
"Responsible Technologies for Responsible People since 1988"
Do not ever believe anything, but seriously trust through
action.
-----Original Message-----
From:[email protected]
[mailto:[email protected]] On Behalf
Of Dave Click
Sent: Friday, August 12, 2011 9:15 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] mechanical vs. electronic kwh
meter
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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