[RE-wrenches] FW: Enphase performance

[Kirpal Khalsa]

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
541-218-0201 m
541-592-3958 o
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