I've got my SMA SB5 on a revenue grade meter and it's actually
under-reported slightly since I started comparing it last August. SMA's
counter has increased by 5649 kWh while the revenue meter has increased
5666 kWh- only 0.3% off. If I remember correctly from their training
session they said they're usually within 1%, but their tech documents
say +/- 5%. YMMV.
-------- Original Message --------
Subject: Re: [RE-wrenches] FW: Enphase performance
From: Kirpal Khalsa <[email protected]>
To: RE-wrenches <[email protected]>
Date: 2010/5/7 12:38
This same issue has come up over the years for us......first with PV
Powered inverters and then noticed in Fronius as well......We have
noticed in most of our grid tied systems that are connected thru a
"revenue grade meter" for Oregon Energy Trust production reporting, that
the inverter always has a higher performance than indicated on the
"utility grade meter". We have seen the discrepency as high as 10%.
Over time this adds up to significant kWh differences. In our
experience the inverter always has the higher kWh reporting, we have
attributed this to the inverter wanting to report a good production
number, to boost their efficiency claims......maybe even more than is
accurate.....I have asked PV Powered and Fronius about this and their
line is that to put a "revenue grade meter" into the inverter would be
cost prohibitive......interesting as the readily available revenue grade
meters are only $30-$60. I would gladly pay that much extra if I
didn't have to wire in an additional meter.
I don't think this problem is unique to the Enphase units (i haven't
installed any of these), I think all inverters should be required to
install the revenue grade meters to give accurate reporting of actual
production. Similar to how states have a "weights and scales" accuracy
certification, energy consumption and production meters should be
similarly calibratable.
--
Sunny Regards,
Kirpal Khalsa
NABCEP Certified Solar PV Installer
Renewable Energy Systems
www.oregonsolarworks.com <http://www.oregonsolarworks.com>
541-218-0201 m
541-592-3958 o
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