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.
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.
Drake
At 12:50 AM 10/11/2010, you wrote:
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'
Nick Soleil
Project Manager
Advanced Alternative Energy Solutions, LLC
PO Box 657
Petaluma, CA 94953
Cell: 707-321-2937
Office: 707-789-9537
Fax: 707-769-9037
From: Jamie Johnson <[email protected]>
To: RE-wrenches <[email protected]>
Sent: Sun, October 10, 2010 5:38:55 AM
Subject: Re: [RE-wrenches] Enphase v. string inverter
Marco,
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.
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.
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.
Performance guarantees with monetary compensation back to the
customer if estimates are not met can be a good thing and improve
the industry IMHO.
Jamie Johnson
General Manager
SOLAR POWER ELECTRIC TM
NABCEP Certified Solar PV Installer #031310-118
(941) 380 - 0098
<http://www.SPEFL.com>www.SPEFL.com
Commercial & Residential
FL State Certified # EC13001765
Sent from my iPhone
On Oct 9, 2010, at 7:07 PM, "Marco Mangelsdorf"
<<mailto:[email protected]>[email protected]> wrote:
Does anyone know of any reports out there from a neutral, 3rd party
which compares an Enphase array with an array using a string
inverter with both arrays on the same unshaded surface?
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.
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.
Thanks,
marco
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