Re: [RE-wrenches] SMA6000U and GT 3.0 FAILURES
Aloha Wrenches: I have been surprised how much equipment has been failing in and out of warranty. - I have recently been put in the unfortunate situation of replacing Sunny Boys that have been dying just out of warranty - I just placed the 50th dead BP module into my module graveyard. - I have been replacing SMA and Xantrex inverters left and right (three more dead inverters yesterday) - Enphase communication issues. Recently, it has been taking 20-40 minutes to reach Enphase customer service This is getting out of hand and taking too much of our staffs time. Have any of you installed the new GT inverters that just came out? They now have a new, larger disconnect enclosure at the bottom of the inverter, and have the guts from the Square D HU-361-RB disconnect inside, with the disconnect handle coming out of it. Perhaps Schneider may be able to work through the bugs that have plagued the GTs. 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: i2p i...@aol.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Thu, June 10, 2010 4:45:51 PM Subject: Re: [RE-wrenches] GT 3.0 FAILURES On Jun 9, 2010, at 10:47:43 AM, August Goers aug...@luminalt.com wrote: maybe Xantrex has fixed it by now? Unlikely, since I continue to replace several sites a 2nd and in one case three times. Don L ___ 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
Re: [RE-wrenches] AC wiring loss on micro-inverters
Hello wrenches and Marv: How many Enphase inverters do you put on a single parallel string? The Enphase manual allows for up to 15, but I have found that a single string of 15 can have very high voltage rise on the AC wiring. Up to 1.5% loss just on the Enphase cables, and that does not take into account resistance at the plug connectors or any home-run wiring. 15 inverters x 190 watts = 2850 watts 2850 watts / 240 Volts = 11.875 Amps (however at the beginning of the string it is 0 Amps) Average Amps on the Enphase cables is 11.875 / 2 = 5.9375 Amps length of contacts + internal wiring = ~6' Total Enphase cabling length (6' x 15 inverters) = ~90' 5.9375 Amps @ 240 V running 90' on #14 AWG CU = 1.4% loss It is pretty hard to design for 1.5% voltage drop if you have to size for 0% loss on your wiring! I hope Enphase will increase the size of the wire in their cables soon. Have you experienced issues with micro-inverters shutting off due to high AC voltages? 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: i2p i...@aol.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Thu, June 10, 2010 4:50:47 PM Subject: Re: [RE-wrenches] Real world PV production On Jun 10, 2010, at 7:57:53 AM, Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com wrote: PV Watts VASTLY underestimate PV production in our area. PV Watts underestimates in Central Ca too. Don ___ 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
Re: [RE-wrenches] AC wiring loss on micro-inverters
Nick, Good to see other wrenches looking at this issue. However, remember that in the interconnect cable between the last and the second to last Enphase, the current is small. If you really want to see how the loss is adding up you need a more detailed analysis that averages the voltage drop for the entire system of interconnect cables. Mark Frye Berkeley solar Electric Systems Hello wrenches and Marv: How many Enphase inverters do you put on a single parallel string? The Enphase manual allows for up to 15, but I have found that a single string of 15 can have very high voltage rise on the AC wiring. Up to 1.5% loss just on the Enphase cables, and that does not take into account resistance at the plug connectors or any home-run wiring. 15 inverters x 190 watts = 2850 watts 2850 watts / 240 Volts = 11.875 Amps (however at the beginning of the string it is 0 Amps) Average Amps on the Enphase cables is 11.875 / 2 = 5.9375 Amps length of contacts + internal wiring = ~6' Total Enphase cabling length (6' x 15 inverters) = ~90' 5.9375 Amps @ 240 V running 90' on #14 AWG CU = 1.4% loss It is pretty hard to design for 1.5% voltage drop if you have to size for 0% loss on your wiring! I hope Enphase will increase the size of the wire in their cables soon. Have you experienced issues with micro-inverters shutting off due to high AC voltages? 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: i2p i...@aol.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Thu, June 10, 2010 4:50:47 PM Subject: Re: [RE-wrenches] Real world PV production On Jun 10, 2010, at 7:57:53 AM, Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com wrote: PV Watts VASTLY underestimate PV production in our area. PV Watts underestimates in Central Ca too. Don ___ 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 ___ 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
Re: [RE-wrenches] AC wiring loss on micro-inverters
Hi Nick, You bring up a good point that Enphase should address more clearly. However, I think the math should be done section by section to accurately account for the wire loss and not the total combined amps for the entire length. If the loss's are too high then reducing the number in each string to an acceptable wire loss would be my recommendation. On Jun 11, 2010, at 12:14 AM, Nick Soleil wrote: Hello wrenches and Marv: How many Enphase inverters do you put on a single parallel string? The Enphase manual allows for up to 15, but I have found that a single string of 15 can have very high voltage rise on the AC wiring. Up to 1.5% loss just on the Enphase cables, and that does not take into account resistance at the plug connectors or any home-run wiring. 15 inverters x 190 watts = 2850 watts 2850 watts / 240 Volts = 11.875 Amps (however at the beginning of the string it is 0 Amps) Average Amps on the Enphase cables is 11.875 / 2 = 5.9375 Amps length of contacts + internal wiring = ~6' Total Enphase cabling length (6' x 15 inverters) = ~90' 5.9375 Amps @ 240 V running 90' on #14 AWG CU = 1.4% loss It is pretty hard to design for 1.5% voltage drop if you have to size for 0% loss on your wiring! I hope Enphase will increase the size of the wire in their cables soon. Have you experienced issues with micro-inverters shutting off due to high AC voltages? 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: i2p i...@aol.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Thu, June 10, 2010 4:50:47 PM Subject: Re: [RE-wrenches] Real world PV production On Jun 10, 2010, at 7:57:53 AM, Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com wrote: PV Watts VASTLY underestimate PV production in our area. PV Watts underestimates in Central Ca too. Don ___ 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 ___ 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
Re: [RE-wrenches] Real world PV production
Joel, Thanks for the information. 35% loss due to to smog or soiling is a big hit and, I'm sure, an exception. Still, if the loss is even 20% it supports the concept that an array here on the cool, cloudy west side of the WA Cascades can perform on par with an equivalent array in a hot, dusty/smoggy location in CA. I'd still like to hear of actual less-than-stellar production numbers recorded in such situations. -Kelly On Jun 10, 2010, at 9:02 AM, Joel Davidson wrote: PVWatts is a good general estimator when you fine-tune the derate factor. For single crystal and multicrystalline arrays, I generally use 0.65 for battery-based PV and inverter systems and 0.82 for batteryless inverter systems. PVWatts annual results are l5% low for Unisolar arrays because PVWatts uses the crystalline silicon temperature coefficient. Even though PVWatts2 may seem more accurate, it does not factor in unique local climate conditions like California coastal morning and afternoon fog or inland persistent winter Tule fog. However, NREL's climate data does include LA's June gloom see http://en.wikipedia.org/wiki/June_Gloom For flat roofs in snowy climates like the Unisolar project in Rochester NY, I deduct 30% from PVWatt's November through March estimates for a fairly accurate annual estimate. Powerlight (now SunPower) also uses an additional 30% monthly derating for flat roofs in snowy locations. PVWatts does not account for really dusty and dirty air locations. Bill Brooks worked at PVUSA and is very knowledgeable about power loss from soiling from agricultural dust in central California. Bill also measured 35% power loss at the Long Beach CA harbor waste-to- energy powerplant PV systems. That location and most LA county freeways experience particulate pollution that not only reduces PV production but causes permanent respiratory damage to children and shorten the lives of elderly people, sort of like the canary in the mine. Joel Davidson - Original Message - From: Kelly Keilwitz, Whidbey Sun Wind To: RE-wrenches Sent: Thursday, June 10, 2010 7:57 AM Subject: Re: [RE-wrenches] Real world PV production Thanks, Don, Performance predictions such as from PV Watts VASTLY underestimate PV production in our area. For example, PV Watts estimates 940 kWh/ kW for a 4:12 pitch at 180˚, whereas such systems are actually producing up to 1300 kWh/kW (as measured by a renenue-grade production meter). We have to set the derating factor to nearly 100% in order for the predictions to match. I assume that is partly due to coarse irradiance data (not accounting for higher irradiance for our location in the rain shadow of the Olympic Mountains), but also due to our clear, cool, windy summers, good natural washing, and (perhaps) dispersed distribution of irradiance. I want to know if the opposite is true: Do performance predictions OVERESTIMATE PV production in areas with historically high irradiance, but significant soiling and temperature issues. Thanks, -Kelly Kelly Keilwitz, P.E. Whidbey Sun Wind Renewable Energy Systems ke...@whidbeysunwind.com 360-678-7131 On Jun 9, 2010, at 8:59 AM, i2p wrote: On Jun 9, 2010, at 8:22:12 AM, Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com wrote: Thanks, Joel How about PV systems away from the coast, in a hotter, dustier location, like Bakersfield, Fresno, Sacramento, Palm Springs, etc? In central CA we do a little better. I casually monitor several systems in this area and expect around 1500-1600 kwh/kw. per year. Don Loweburg ___ 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
Re: [RE-wrenches] AC wiring loss on micro-inverters
Did you notice that in my calculation I divided the total amperage by 2 to get the average ampacity across the string. This seems to be the best way to deal with that. Otherwise the loss would have been over 2.8% 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: ma...@berkeleysolar.com ma...@berkeleysolar.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Fri, June 11, 2010 7:02:00 AM Subject: Re: [RE-wrenches] AC wiring loss on micro-inverters Nick, Good to see other wrenches looking at this issue. However, remember that in the interconnect cable between the last and the second to last Enphase, the current is small. If you really want to see how the loss is adding up you need a more detailed analysis that averages the voltage drop for the entire system of interconnect cables. Mark Frye Berkeley solar Electric Systems Hello wrenches and Marv: How many Enphase inverters do you put on a single parallel string? The Enphase manual allows for up to 15, but I have found that a single string of 15 can have very high voltage rise on the AC wiring. Up to 1.5% loss just on the Enphase cables, and that does not take into account resistance at the plug connectors or any home-run wiring. 15 inverters x 190 watts = 2850 watts 2850 watts / 240 Volts = 11.875 Amps (however at the beginning of the string it is 0 Amps) Average Amps on the Enphase cables is 11.875 / 2 = 5.9375 Amps length of contacts + internal wiring = ~6' Total Enphase cabling length (6' x 15 inverters) = ~90' 5.9375 Amps @ 240 V running 90' on #14 AWG CU = 1.4% loss It is pretty hard to design for 1.5% voltage drop if you have to size for 0% loss on your wiring! I hope Enphase will increase the size of the wire in their cables soon. Have you experienced issues with micro-inverters shutting off due to high AC voltages? 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: i2p i...@aol.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Thu, June 10, 2010 4:50:47 PM Subject: Re: [RE-wrenches] Real world PV production On Jun 10, 2010, at 7:57:53 AM, Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com wrote: PV Watts VASTLY underestimate PV production in our area. PV Watts underestimates in Central Ca too. Don ___ 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 ___ 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 ___ 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
Re: [RE-wrenches] AC wiring loss on micro-inverters
Maybe Marv can help out here. I¹ve talked with tech support at Enphase and am under the impression that you can center tap their branch circuits to reduce voltage drop. This technique was used on a project that we profiled in SolarPro: http://solarprofessional.com/article/?file=SP3_2_pg92_Projects_1search= David Brearley, Senior Technical Editor SolarPro magazine On 6/11/10 2:50 PM, Nick Soleil nicksoleilso...@yahoo.com wrote: Did you notice that in my calculation I divided the total amperage by 2 to get the average ampacity across the string. This seems to be the best way to deal with that. Otherwise the loss would have been over 2.8% 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: ma...@berkeleysolar.com ma...@berkeleysolar.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Fri, June 11, 2010 7:02:00 AM Subject: Re: [RE-wrenches] AC wiring loss on micro-inverters Nick, Good to see other wrenches looking at this issue. However, remember that in the interconnect cable between the last and the second to last Enphase, the current is small. If you really want to see how the loss is adding up you need a more detailed analysis that averages the voltage drop for the entire system of interconnect cables. Mark Frye Berkeley solar Electric Systems Hello wrenches and Marv: How many Enphase inverters do you put on a single parallel string? The Enphase manual allows for up to 15, but I have found that a single string of 15 can have very high voltage rise on the AC wiring. Up to 1.5% loss just on the Enphase cables, and that does not take into account resistance at the plug connectors or any home-run wiring. 15 inverters x 190 watts = 2850 watts 2850 watts / 240 Volts = 11.875 Amps (however at the beginning of the string it is 0 Amps) Average Amps on the Enphase cables is 11.875 / 2 = 5.9375 Amps length of contacts + internal wiring = ~6' Total Enphase cabling length (6' x 15 inverters) = ~90' 5.9375 Amps @ 240 V running 90' on #14 AWG CU = 1.4% loss It is pretty hard to design for 1.5% voltage drop if you have to size for 0% loss on your wiring! I hope Enphase will increase the size of the wire in their cables soon. Have you experienced issues with micro-inverters shutting off due to high AC voltages? 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: i2p i...@aol.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Thu, June 10, 2010 4:50:47 PM Subject: Re: [RE-wrenches] Real world PV production On Jun 10, 2010, at 7:57:53 AM, Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com wrote: PV Watts VASTLY underestimate PV production in our area. PV Watts underestimates in Central Ca too. Don ___ 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 http://www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org http://www.members.re-wrenches.org ___ 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 http://www.members.re-wrenches.org ___ 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 ___ 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
Re: [RE-wrenches] AC wiring loss on micro-inverters
I guess all this does is effectively reduce the number of inverters in each string, and create two strings from one (but without additional homerun string wiring). So you need two factory pigtails instead of one for each original string for the center tap j-box, but a small price to pay for increased system efficiency. Good idea. Kirk Herander Vermont Solar Engineering 802.863.1202 NABCEP(tm) Certified Solar Installer NYSERDA-eligible Installer VT Solar Incentive Program Partner _ From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of David Brearley Sent: Friday, June 11, 2010 4:04 PM To: RE-wrenches Subject: Re: [RE-wrenches] AC wiring loss on micro-inverters Maybe Marv can help out here. I've talked with tech support at Enphase and am under the impression that you can center tap their branch circuits to reduce voltage drop. This technique was used on a project that we profiled in SolarPro: http://solarprofessional.com/article/?file=SP3_2_pg92_Projects_1 http://solarprofessional.com/article/?file=SP3_2_pg92_Projects_1search= search= David Brearley, Senior Technical Editor SolarPro magazine On 6/11/10 2:50 PM, Nick Soleil nicksoleilso...@yahoo.com wrote: Did you notice that in my calculation I divided the total amperage by 2 to get the average ampacity across the string. This seems to be the best way to deal with that. Otherwise the loss would have been over 2.8% 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 ___ 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
[RE-wrenches] desperately seeking MC4 connectors
Anyone have any line on some MC4s or have some, even a paltry quantity, that they're willing to part with? Thanks, marco ___ 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
Re: [RE-wrenches] Real world PV production
Kelly, Your area is a prime example of needing to find a data site that is not geographically closest, but climatically closest. In Washington, the microclimates are so extreme, that data from PV:Watts must be manually selected. It is not because the program is that far off, it is the climatic input information that is not relevant to your location. Bill. From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Kelly Keilwitz, Whidbey Sun Wind Sent: Friday, June 11, 2010 9:55 AM To: RE-wrenches Subject: Re: [RE-wrenches] Real world PV production Joel, Thanks for the information. 35% loss due to to smog or soiling is a big hit and, I'm sure, an exception. Still, if the loss is even 20% it supports the concept that an array here on the cool, cloudy west side of the WA Cascades can perform on par with an equivalent array in a hot, dusty/smoggy location in CA. I'd still like to hear of actual less-than-stellar production numbers recorded in such situations. -Kelly On Jun 10, 2010, at 9:02 AM, Joel Davidson wrote: PVWatts is a good general estimator when you fine-tune the derate factor. For single crystal and multicrystalline arrays, I generally use 0.65 for battery-based PV and inverter systems and 0.82 for batteryless inverter systems. PVWatts annual results are l5% low for Unisolar arrays because PVWatts uses the crystalline silicon temperature coefficient. Even though PVWatts2 may seem more accurate, it does not factor in unique local climate conditions like California coastal morning and afternoon fog or inland persistent winter Tule fog. However, NREL's climate data does include LA's June gloom see http://en.wikipedia.org/wiki/June_Gloom For flat roofs in snowy climates like the Unisolar project in Rochester NY, I deduct 30% from PVWatt's November through March estimates for a fairly accurate annual estimate. Powerlight (now SunPower) also uses an additional 30% monthly derating for flat roofs in snowy locations. PVWatts does not account for really dusty and dirty air locations. Bill Brooks worked at PVUSA and is very knowledgeable about power loss from soiling from agricultural dust in central California. Bill also measured 35% power loss at the Long Beach CA harbor waste-to-energy powerplant PV systems. That location and most LA county freeways experience particulate pollution that not only reduces PV production but causes permanent respiratory damage to children and shorten the lives of elderly people, sort of like the canary in the mine. Joel Davidson - Original Message - From: Kelly Keilwitz, Whidbey Sun mailto:ke...@whidbeysunwind.com Wind To: RE-wrenches mailto:re-wrenches@lists.re-wrenches.org Sent: Thursday, June 10, 2010 7:57 AM Subject: Re: [RE-wrenches] Real world PV production Thanks, Don, Performance predictions such as from PV Watts VASTLY underestimate PV production in our area. For example, PV Watts estimates 940 kWh/kW for a 4:12 pitch at 180˚, whereas such systems are actually producing up to 1300 kWh/kW (as measured by a renenue-grade production meter). We have to set the derating factor to nearly 100% in order for the predictions to match. I assume that is partly due to coarse irradiance data (not accounting for higher irradiance for our location in the rain shadow of the Olympic Mountains), but also due to our clear, cool, windy summers, good natural washing, and (perhaps) dispersed distribution of irradiance. I want to know if the opposite is true: Do performance predictions OVERESTIMATE PV production in areas with historically high irradiance, but significant soiling and temperature issues. Thanks, -Kelly Kelly Keilwitz, P.E. Whidbey Sun Wind Renewable Energy Systems ke...@whidbeysunwind.com 360-678-7131 On Jun 9, 2010, at 8:59 AM, i2p wrote: On Jun 9, 2010, at 8:22:12 AM, Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com wrote: Thanks, Joel How about PV systems away from the coast, in a hotter, dustier location, like Bakersfield, Fresno, Sacramento, Palm Springs, etc? In central CA we do a little better. I casually monitor several systems in this area and expect around 1500-1600 kwh/kw. per year. Don Loweburg ___ 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
Re: [RE-wrenches] PVWatts Module Temperature Coefficient
Joel and All, PV:WATTS is just a very simple simulation. You can make simple corrections for temp coefficient if you like, but if you want better accuracy, you have to go to a more sophisticated program like PVSyst or PVSol. Bill. -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Joel Davidson Sent: Monday, April 19, 2010 9:03 PM To: RE-wrenches Subject: Re: [RE-wrenches] PVWatts Module Temperature Coefficient Dave, Thank you. PVWatts does not predict accurately Unisolar (-0.21%/degC) or Sunpower (-0.38%/degC) or Sanyo HIT ( -0.336%/degC). In Los Angeles, I measured 6% more annual kWh from Unisolar over a 3 year period and over 10% more from Sunpower so far this year. Joel Davidson - Original Message - From: Dave Click davecl...@fsec.ucf.edu To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Monday, April 19, 2010 7:01 AM Subject: Re: [RE-wrenches] PVWatts Module Temperature Coefficient (was Enphase derate) It seems to be -0.5%/degC: http://rredc.nrel.gov/solar/calculators/PVWATTS/moreabout.html Original Message Subject: [RE-wrenches] PVWatts Module Temperature Coefficient (was Enphase derate) From: Joel Davidson joel.david...@sbcglobal.net To: RE-wrenches re-wrenches@lists.re-wrenches.org Date: 2010/4/18 12:23 Wrenches, PVWatts does not accurately predicate Unisolar and Sunpower module performance because it uses a generic single crystal silicon solar module power temperature coefficient (I think -0.4% per degree C). Does someone have the technical paper that specifies PVWatts module temperature coefficient? Thank you. Joel Davidson ___ 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 ___ 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
Re: [RE-wrenches] Isofoton modules
We did a 6 kW system 6 years ago using 160 watt, 160 watt modules, and the client recently called back and asked us to add another 4 kW. We no longer install this brand of module and have lost track who in US supplies them. We found them to be well made and look great, but we just started using other brands and slowly moved in other directions. Their web page indicates they have or are building a plant in US, so I assume they are still around, but do not know who is stocking these. We need the 160 watt size to best match the modules already installed, but looks like they have re-worked these to now be 24 volt modules and our original ones were 12 volt (17 Voc), but we can work around that. Any idea? Thanks, Jeff Yago _ Netscape. Just the Net You Need. ___ 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
Re: [RE-wrenches] AC wiring loss on micro-inverters
I just attended a training class in Philly last week by Enphase technical staff and my notes say they suggest up to 15 micro-inverters @ 190 watts each per string with no problem. They also are now shipping their dual module micro-inverter which should help with this wire issue since this model #D380 has two #M190 units built into the same box which is only slightly larger thana single micro-inverter. Since this new dual micro-inverter does NOT have the AC pass-through wire built-in, you are no longer limited to the wire size that comes in and out for the 240 VAC connections. HOWEVER, they require you to purchase this awful looking multi-tap pigtail cable for the AC connections which has a pre-wired connector spaced the expected distance apart the micro-inverters would be installed, and this is a $950 item for every six dual micro-inverters. When I saw this thing I thought is was a python that had swalled six pepsi cans! Not sure what this will look like on a roof or how well it can be hidden behind the array, but it uses a larger wire size so perhaps the wire loss issue has been resolved. Jeff Yago DTI SolarNetscape. Just the Net You Need. ___ 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
Re: [RE-wrenches] AC wiring loss on micro-inverters
Hi fellow wrenches forgive me if this has been said. The AC is a special problem on MIcro inverters because the long runs modules to service are now in the AC section of the system. The DC connections are very short. The utility has a +- 5% normal tolerance, which leaves us with only 5% to count on. If the grid is high any voltage rise would put us very close to high voltage shut down. The manufacture is trying to help us prevent nuisance shut downs, and is looking for 1% voltage rise. Voltage rise or drop is easily calculated in English units by Vr=2KIL/CM where K is the coefficient of resistance for copper (12.9) I is the current in amps, (0.82x#of M190 inverters) L is the one way length of the wire run. or equally straight forward is Vr= 2LIR/1000 where the L is the one way length, I is the current as above, R is the resistance per 1000 feet of wire. The CM and R values are from Chapter 9 Table 8 of the NEC Darryl --- On Fri, 6/11/10, Jeff Yago jry...@netscape.com wrote: From: Jeff Yago jry...@netscape.com Subject: Re: [RE-wrenches] AC wiring loss on micro-inverters To: k...@vtsolar.com, RE-wrenches re-wrenches@lists.re-wrenches.org Date: Friday, June 11, 2010, 5:42 PM I just attended a training class in Philly last week by Enphase technical staff and my notes say they suggest up to 15 micro-inverters @ 190 watts each per string with no problem. They also are now shipping their dual module micro-inverter which should help with this wire issue since this model #D380 has two #M190 units built into the same box which is only slightly larger than a single micro-inverter. Since this new dual micro-inverter does NOT have the AC pass-through wire built-in, you are no longer limited to the wire size that comes in and out for the 240 VAC connections. HOWEVER, they require you to purchase this awful looking multi-tap pigtail cable for the AC connections which has a pre-wired connector spaced the expected distance apart the micro-inverters would be installed, and this is a $950 item for every six dual micro-inverters. When I saw this thing I thought is was a python that had swalled six pepsi cans! Not sure what this will look like on a roof or how well it can be hidden behind the array, but it uses a larger wire size so perhaps the wire loss issue has been resolved. Jeff Yago DTI Solar Netscape. Just the Net You Need. -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 ___ 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
Re: [RE-wrenches] Real world PV production
Just my two cents worth, from measured data we get about 1250 kWh per watt in Minnesota per year this is measured over roughly 8 years, I had more trouble with the monitoring system than the array. The winter measured lower than predicted, and the summer measured higher. The winter is easy to explain in that we have a lot of snow and loss because of snow cover. The summer was higher and I have no idea why. The average was about the same as prediction. Darryl --- On Fri, 6/11/10, Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com wrote: From: Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com Subject: Re: [RE-wrenches] Real world PV production To: RE-wrenches re-wrenches@lists.re-wrenches.org Date: Friday, June 11, 2010, 11:54 AM Joel, Thanks for the information. 35% loss due to to smog or soiling is a big hit and, I'm sure, an exception. Still, if the loss is even 20% it supports the concept that an array here on the cool, cloudy west side of the WA Cascades can perform on par with an equivalent array in a hot, dusty/smoggy location in CA. I'd still like to hear of actual less-than-stellar production numbers recorded in such situations. -Kelly On Jun 10, 2010, at 9:02 AM, Joel Davidson wrote: PVWatts is a good general estimator when you fine-tune the derate factor. For single crystal and multicrystalline arrays, I generally use 0.65 for battery-based PV and inverter systems and 0.82 for batteryless inverter systems. PVWatts annual results are l5% low for Unisolar arrays because PVWatts uses the crystalline silicon temperature coefficient. Even though PVWatts2 may seem more accurate, it does not factor in unique local climate conditions like California coastal morning and afternoon fog or inland persistent winter Tule fog. However, NREL's climate data does include LA's June gloom see http://en.wikipedia.org/wiki/June_Gloom For flat roofs in snowy climates like the Unisolar project in Rochester NY, I deduct 30% from PVWatt's November through March estimates for a fairly accurate annual estimate. Powerlight (now SunPower) also uses an additional 30% monthly derating for flat roofs in snowy locations. PVWatts does not account for really dusty and dirty air locations. Bill Brooks worked at PVUSA and is very knowledgeable about power loss from soiling from agricultural dust in central California. Bill also measured 35% power loss at the Long Beach CA harbor waste-to-energy powerplant PV systems. That location and most LA county freeways experience particulate pollution that not only reduces PV production but causes permanent respiratory damage to children and shorten the lives of elderly people, sort of like the canary in the mine. Joel Davidson- Original Message -From: Kelly Keilwitz, Whidbey Sun WindTo: RE-wrenchesSent: Thursday, June 10, 2010 7:57 AMSubject: Re: [RE-wrenches] Real world PV production Thanks, Don,Performance predictions such as from PV Watts VASTLY underestimate PV production in our area. For example, PV Watts estimates 940 kWh/kW for a 4:12 pitch at 180˚, whereas such systems are actually producing up to 1300 kWh/kW (as measured by a renenue-grade production meter). We have to set the derating factor to nearly 100% in order for the predictions to match. I assume that is partly due to coarse irradiance data (not accounting for higher irradiance for our location in the rain shadow of the Olympic Mountains), but also due to our clear, cool, windy summers, good natural washing, and (perhaps) dispersed distribution of irradiance. I want to know if the opposite is true: Do performance predictions OVERESTIMATE PV production in areas with historically high irradiance, but significant soiling and temperature issues. Thanks,-Kelly Kelly Keilwitz, P.E.Whidbey Sun WindRenewable Energy systemske...@whidbeysunwind.com360-678-7131 On Jun 9, 2010, at 8:59 AM, i2p wrote: On Jun 9, 2010, at 8:22:12 AM, Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com wrote: Thanks, Joel How about PV systems away from the coast, in a hotter, dustier location, like Bakersfield, Fresno, Sacramento, Palm Springs, etc? In central CA we do a little better. I casually monitor several systems in this area and expect around 1500-1600 kwh/kw. per year. Don Loweburg -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 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings:
[RE-wrenches] Housekeeping: product needs
Hi gang. If you have a comments on this post, please contact me off list. Some time ago we decided we should allow requests for hard to find products and replacement products on the list. This has me a bit worried, specially as systems become older and products damaged by weather etc. need to be replaced; and specially as the number of Wrench List members creeps steadily higher. There has been a minor flow of these requests lately, when in the past we have practically had none. At least for now, let's continue allowing these requests, because I cannot think of another or better means of finding these things when you need them. But in order to keep this to a dull roar, please follow these guidelines: 1. First, please exhaust the methods you can think of for finding the products through normal channels, like your distributors or the former manufacturers. 2. Please always ask Wrenches to contact you off-list with their responses. 3. When responding, please email the seeker directly and off-list instead of on the list. Thanks much, Wrenches. ___ 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
