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

[Mark Frye]

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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