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Hello Joel,<br><br>
The issue is that over half the array was in shade. I don't think
there would have been enough string voltage to start a string
inverter. <br><br>
Cheers,<br><br>
Drake <br><br>
<br><br>
<br>
At 11:33 AM 10/11/2010, you wrote:<br>
<blockquote type=cite class=cite cite=""><font size=2>Hello Drake,<br>
</font> <br>
<font size=2>I have observed hundreds of PV systems in the early morning
and can say without doubt that string inverters are not inherently slow
to wake up.<br>
</font> <br>
<font size=2>For example, today my 12 year old SW4048 with a single
crystal PV array facing south at 12 and 18 degrees tilt and my SB2100
with a single crystal PV array facing south at 18 degrees both were
putting out power at 7:45 am when the sun was 9 degrees above the horizon
at azimuth 105 degrees. Today the sky is clear and the sun rose in Los
Angeles at 6:57 am.<br>
</font> <br>
<font size=2>I have seen systems with 100 kW Xantrex inverters and flat
Unisolar arrays wake up before the morning sun rose above the horizon.
Granted the systems were putting out less than 5 kW, but the inverters
were on.<br>
</font> <br>
<font size=2>See you all at the solar conference.<br>
</font> <br>
<font size=2>Best regards,<br>
Joel Davidson<br>
</font> <br>
<br>
----- Original Message ----- <br>
<dl>
<dd>From:</b>
<a href="mailto:drake.chamberlin@redwoodalliance.org">Drake</a> <br>
<dd>To:</b>
<a href="mailto:re-wrenches@lists.re-wrenches.org">RE-wrenches</a> <br>
<dd>Sent:</b> Monday, October 11, 2010 6:39 AM<br>
<dd>Subject:</b> Re: [RE-wrenches] Enphase v. string inverter<br><br>
<dd>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>
<dd>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>
<dd>Drake <br><br>
<br><br>
<dd>At 12:50 AM 10/11/2010, you wrote:<br>
<blockquote type=cite class=cite cite="">
<dd> 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>
<dd>Nick Soleil<br>
<dd>Project Manager<br>
<dd>Advanced Alternative Energy Solutions, LLC<br>
<dd>PO Box 657<br>
<dd>Petaluma, CA 94953<br>
<dd>Cell: 707-321-2937<br>
<dd>Office: 707-789-9537<br>
<dd>Fax: 707-769-9037<br><br>
<br><br>
<dd><font face="Tahoma" size=2>From:</b> Jamie Johnson
<jjohnson@spefl.com><br>
<dd>To:</b> RE-wrenches <re-wrenches@lists.re-wrenches.org><br>
<dd>Sent:</b> Sun, October 10, 2010 5:38:55 AM<br>
<dd>Subject:</b> Re: [RE-wrenches] Enphase v. string inverter<br>
</font><br>
<dd>Marco,<br><br>
<dd>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>
<dd>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>
<dd>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>
<dd>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>
<dd>Jamie Johnson<br>
<dd>General Manager<br>
<dd>SOLAR POWER ELECTRIC TM<br>
<dd>NABCEP Certified Solar PV Installer #031310-118<br>
<dd>(941) 380 - 0098<br>
<dd><a href="http://www.SPEFL.com">www.SPEFL.com</a><br>
<dd>Commercial & Residential<br>
<dd>FL State Certified # EC13001765<br><br>
<dd>Sent from my iPhone<br><br>
<dd>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="">
<dd>Does anyone know of any reports out there from a neutral, 3rd</sup>
party which compares an Enphase array with an array using a string
inverter with both arrays on the same unshaded surface?<br><br>
<dd> <br><br>
<dd>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>
<dd> <br><br>
<dd>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>
<dd> <br><br>
<dd>Thanks,<br><br>
<dd>marco<br><br>
<dd> <br>
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