The temperature correction is the concern. I have heard lots of stories of inverters dieing when it gets to cold. Look in the code book 690.7 at the temperature correction table. Go to weather.com and find your record low temperature. Find you Tc factor and will your senerios work? I have heard from a sunny boy rep that it is OK to over power by 1.25% darryl
--- On Mon, 4/19/10, Dana <d...@solarwork.com> wrote: From: Dana <d...@solarwork.com> Subject: Re: [RE-wrenches] overfeed 7kW gridtie inverter or drop a mod per string? To: "'RE-wrenches'" <re-wrenches@lists.re-wrenches.org> Date: Monday, April 19, 2010, 4:31 PM Many times we switch to another module manufacturer as one will not fit or another inverter manufacturer. PVPowered has a more relaxed window and we have had fine success with them when SMA does not fit. Cold is the dictator and the 600 VDC threshold. Thanks, Dana Orzel Great Solar Works, Inc web - www.solarwork.com E - d...@solarwork.com V - 970.626.5253 F - 970.626.4140 C - 970.209.4076 "We have been slow to give up on the myth of the Earth's generosity. Rather grandly, we have overdrawn our accounts." Barbara Kingsolver - Water is life. From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Jim MacDonald Sent: Monday, April 19, 2010 2:37 PM To: RE-wrenches@lists.re-wrenches.org Subject: [RE-wrenches] overfeed 7kW gridtie inverter or drop a mod per string? For a straight grid-tie system@ 10 degree tilt, 180 azimuth, zero/little shade, NYC avg 4.29 kWh/m²/day. Feed an SMA7000 with (3) strings of 11 Suntech STP275’s [9.075 kWdc] Or Do strings of 10, so itd be 8.250 kWdc into the 7 kWac inverter. Strings of 11= 491.7 Voc; 386 Vmp Strings of 10= 447 Voc; 351 Vmp The tradeoff would be power clipping at/around noon in the sunny months in the 9.075 kW scenario; Inverter sleeping late every morning and retiring early in the evenings in the lowered voltage scenario. Trying to figure out which would yield more kWh at the end of the year. Any ideas appreciated, thanks Jim MacDonald Solar Energy Systems, LLC Brooklyn, NY 11222 www.solarEsystems.com No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.801 / Virus Database: 271.1.1/2819 - Release Date: 04/19/10 00:31:00 -----Inline Attachment Follows----- _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
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