[RE-wrenches] Enphase and oversizing
Nick Soleil
nicksoleilsolar at yahoo.com
Mon Jan 17 07:55:34 PST 2011
Enphase has been very clear that the M-190 can be paired with modules up to 230
watts DC, with a slight amount of power loss
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: Randy <randy at positiveenergysolar.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Sun, January 16, 2011 2:35:27 PM
Subject: Re: [RE-wrenches] Enphase and oversizing
Hi Marco,
I would doubt you would have clipping where you except for edge of cloud effect
but here are that factors that we considered:
1. A low coefficient of power module such as sanyo or thin film running
at lower temperatures would mean the module runs closer to its rating depending
on ambient temperature
2. In cold, high altitude areas such as Colorado and NM where the module
temp frequently is close to 25 degree C
3. In ground mount or windy situations where the delta T to ambient is
very small (might apply to you)
4. Where irradiance is regularly running above 1000W/m2 and the array is
mounted on a tracker or when there is snow on the ground and albedo is
reflecting more sunlight.
We have seen output clipping of any inverter that is rated less than the module
STC DC watts in NM including enphase.
Thanks,
Randy
Randy Sadewic
Positive Energy
Office: 505 424-1112
Cell: 505 570-0137
From:re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Kent Osterberg
Sent: Saturday, January 15, 2011 6:13 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Enphase and oversizing
Marco,
Enphase has a white paper on this topic that seems consistent with
observations. The results depend on the roof and the location. But even on a
12:12 roof in Denver they compute less than 0.6% annual loss with new clean
235-watt modules. I've looked for clipping events on systems with Sharp
235-watt modules that I've installed on 4:12 roofs and haven't seen much -
rarely are they even near 199 watts for a few minutes. Obviously it'll be more
significant with larger modules like the SW 245, but I doubt that occasional
clipping that amounts to less than 1% of the possible annual output should be
characterized as wasting the customer's money. That much can be lost in
selecting a different inverter.
I suspect and hope that a larger inverter is in the works. But in the mean time
I see putting 245-watt modules on the 190-watt inverters as working the inverter
hard. Would you hesitate to put 2400 watts of PV modules on a 2-kW inverter?
Kent Osterberg
Blue Mountain Solar, Inc.
Marco Mangelsdorf wrote:
To those of you installing Enphases.
Other than their 210 only working with Sanyo and SunPower modules, the vast
majority of other mods only work with the Enphase 190.
Question: what’s the max size module that you’re comfortable using with the
Enphase 190?
In there here parts I’m seeing competitors pairing the Enphase 190 with modules
in the 230+ watt range. Some are even pairing the 190 with the SolarWorld 245.
Talk about wasting the customer’s money….
This strikes me as a bad design that essentially has the homeowner throwing away
some of his/her money on unused PV horsepower. Here in the tropics, where the
edge-of-cloud effect can be seen on a regular basis, I see DC nameplate AND
higher coming out on the AC side of my systems.
I’m wondering where others are on this question of oversizing.
Thanks,
marco
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