[RE-wrenches] FW: Enphase performance

[Dave Click]

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 <solarworks at gmail.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
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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