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I'm now monitoring a 5.376 kW system we recently installed. The sun is
barely up, with light clouds, and a portion of the array is still in
shade. The system is putting out 700 watts. A string inverter
would probably be waiting to start. <br><br>
My main problem with the Enphase is the 199 watt limit to its
output. The inverters are rated for up to 235 watt modules.
This 224 watt module array spends a fair amount of time at full inverter
capacity during cool sunny days. Maybe these inverters should not
be used with over 210 watt modules. <br><br>
Drake <br><br>
<br><br>
At 12:50 AM 10/11/2010, you wrote:<br>
<blockquote type=cite class=cite cite=""> The main
advantage of Enphase is the module level monitoring. However, the
increased output due to partial shading can be significant. I was
at a 6 year old PV site this week, and a tree had grown up near the base
of the roof. Branches were casting a few minor shadows on the
array, but was wiping out 75% of the production. I can assure you,
those 9 modules would have been producing '50+% greater output'<br>
Nick Soleil<br>
Project Manager<br>
Advanced Alternative Energy Solutions, LLC<br>
PO Box 657<br>
Petaluma, CA 94953<br>
Cell: 707-321-2937<br>
Office: 707-789-9537<br>
Fax: 707-769-9037<br><br>
<br>
<br>
<font face="Tahoma" size=2><b>From:</b> Jamie Johnson
<jjohnson@spefl.com><br>
<b>To:</b> RE-wrenches <re-wrenches@lists.re-wrenches.org><br>
<b>Sent:</b> Sun, October 10, 2010 5:38:55 AM<br>
<b>Subject:</b> Re: [RE-wrenches] Enphase v. string inverter<br>
</font><br>
Marco,<br><br>
The last I heard the NREL was testing enphase vs. a string inverter, they
were also suppose to test enphase vs. A competitors module level mpp
tracking. Not sure if that performance test is complete yet.
<br><br>
I have seen 1 independent unshaded test ( potentially biased ) which IIRC
showed enphase ~1% less than a string inverter, this seems to match the
inverters CEC rating.<br><br>
What we see around here is an over estimate of kWh production by the
selling contractor using enphase, sometimes by 50+% greater than unshaded
kWh estimates.<br><br>
Performance guarantees with monetary compensation back to the customer if
estimates are not met can be a good thing and improve the industry
IMHO.<br><br>
Jamie Johnson<br>
General Manager<br>
SOLAR POWER ELECTRIC TM<br>
NABCEP Certified Solar PV Installer #031310-118<br>
(941) 380 - 0098<br>
<a href="http://www.SPEFL.com">www.SPEFL.com</a><br>
Commercial & Residential<br>
FL State Certified # EC13001765<br><br>
Sent from my iPhone<br><br>
On Oct 9, 2010, at 7:07 PM, "Marco Mangelsdorf"
<<a href="mailto:marco@pvthawaii.com">marco@pvthawaii.com</a>>
wrote:<br><br>
<blockquote type=cite class=cite cite="">Does anyone know of any reports
out there from a neutral, 3<sup>rd</sup> party which compares an Enphase
array with an array using a string inverter with both arrays on the same
unshaded surface?<br><br>
<br><br>
Some Enphase peddlers here are saying that the energy harvest from an
Enphase system is going to be better since they supposedly come on sooner
and stay on later in the day.<br><br>
<br><br>
One guy is actually saying that the Enphase inverters come on before the
sun comes over the horizon. Maybe from the same family that
claimed that a-Si modules produced power from the moonlight.<br><br>
<br><br>
Thanks,<br><br>
marco<br><br>
<br>
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