[RE-wrenches] Warranty Claim Based On Enphase Monitoring Data

matt at solar-energy-solutions.com matt at solar-energy-solutions.com
Thu Jun 9 06:47:50 PDT 2011


Mark,

We have nine Trina modules on our roof with Enphase.  Enphase says the
array has produced 2,680 kWh to date.  The revenue grade meter 12 feet
away says 2,564.  Until I hear otherwise I am reluctant to consider
Enphase reporting precise.  It seems to be similar to what I would expect
from a string inverter.  I would be delighted to hear more anecdotes
confirming your observations.


Regards,

Matt


Matthew Partymiller
Solar Energy Solutions LLC
(859) 312-7456
matt at solar-energy-solutions.com


> Folks,
>
> Has anyone used Enphase monitoring data to get warranty replacement on new
> modules with sub par yield?
>
> I have several interesting questions stemming from access to Enphase
> module
> level monitoring data.
>
> Looking at data from a larger site (80 modules) with no shading issues,
> instant power production indicates a high degree of uniformity in panel
> power (Sharp NU-U240F1 and D380) easily within 1%.
>
> So what can we now say about the precision and accuracy of this monitoring
> data? It seems the old school thinking for string inverters was all the
> monitors were 5% off and reporting 5% more power than actual.
>
> Based on the data that I am looking at, it seems the microinverter meters
> must be fairly precise and possibly fairly accurate as well. Uniformity of
> module performance must also be fairly high.
>
> In any case, this data clearly shows a single module that is not
> performing
> as well as it's cohorts. For power levels above 50% of STC, it averages 9%
> less power than all other modules in the system. So off to Sharp for a
> warranty replacement? Yes, but, what if I am 5% low on the report from my
> inverter meter and 5% lower on my power from this one module? What if the
> module gets back to Sharp and they say it is within spec, now the costs
> are
> all mine?
>
> Interestingly enough, access to this monitoring data is making more work
> for
> me as an installer. With a string inverter, I would monitor power
> production
> readings monthly and be happy so long as yields were higher than what I
> projected when I designed and bid the job. Pretty much fire and forget.
>
> Now I am spending time on evaluating this data and doing the work to
> change
> out the module under warranty and so forth. I am going to end up putting
> in
> quite a few hours into this for what: to recapture 10% of 1/80 of total
> system yield
.0.0013%.
>
> I am not complaining, just musing over this interesting evolution.
>
> Mark Frye
> Berkeley Solar Electric Systems
> 303 Redbud Way
> Nevada City,  CA 95959
> (530) 401-8024
> www.berkeleysolar.com
>
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