[RE-wrenches] Enphase performance
My biz partner has an Enphase system with BP Solar mods. He believes that the web-based monitoring system may be reporting on the high side as far as kWH performance over time. That is, he suspects that what he's seeing may not be accurate. Anyone out there have a similar experience? 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-wrenches] Enphase performance
I just don't understand why going over 20 percent of module nameplate to nameplate inverter rating makes any sense. I regularly see 120-130 percent of nameplate amperage coming off of the array on our office due to edge of cloud. So I have to disagree with Dana in this instance. I see this a bad design especially since lower output mods are so readily available these days. And what's up with the Enphase 210? Doesn't it say on their latest compatibility list (March 2010) that it's only good for the Sanyo line? What's up with that especially since I know that one other manufacturer is signing off on using the Enphase 210 with their 210-watt module, apparently with Enphase's approval? Marv-why is your Enphase 210 only listed for use with the Sanyo line when there's a growing number of 210+ watt mods out there these days? Thanks, marco I've been concerned about pairing higher wattage modules (~230W) with the 190W Enphase fearing a lot of clipping and power loss when the modules are at full power. I did some modeling of this setup in PVSYST and found that the expected loss from the inverter being underpowered is 0 - 0.2% annually depending on the assumptions. The modeling was for northwestern Washington State. A fifth of a percent seems pretty negligible to me and is easily offset by removing module mismatch from the equation. So, I'm convinced that matching modules in the 230W range with the 190W Enphase inverters is a good design. I recently installed 4kW of 230s with the Enphase 190s and have seen their output as high as 199W. Dana Dana Brandt Ecotech Energy Systems, LLC www.ecotechenergy.com d...@ecotechenergy.com 360.510.0433 On Fri, May 7, 2010 at 4:48 PM, Chris Worcester wrote: Do the Enphase inverters clip the output power to their rating like other manufacturer's? So a M190 can only put out 190 watts max? I have had this question for a bit now on system performances using Enphase in designs during our cold spring and fall days. Sincerely, Chris Worcester Solar Wind Works NABCEP Certified PV Installer Phone: 530-582-4503 Fax: 530-582-4603 www.solarwindworks.com <http://www.solarwindworks.com/> ch...@solarwindworks.com "Proven Energy Solutions" From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Westbrock Sent: Friday, May 07, 2010 10:33 AM To: RE-wrenches Subject: Re: [RE-wrenches] Enphase performance The over-reporting of energy that Randy refers to below was much higher than any discrepancy based on monitoring resolution. We have a pyranometer at the site, and Enphase reported energy production as high as 38% higher that predicted from irradiance data, as well as 38% higher than the string inverter portion of the same system. Individual microinverters showed instantaneous power output as high as 285 W from a nominal 190 W unit. Enphase explained that there was a software glitch that was resulting in "double counting". It took them over two months to correct this issue, time which is lost from our experimental comparison of string vs. microinverter. They indicated that this seemed to be an isolated situation, but I wonder how many Enphase customers are reporting miraculous performance from their system without verifying via another meter. Screen shot of a day's power production of 22 M190 microinverters (nominal 4180 watts AC): Error! Filename not specified. Mark Mark Westbrock NABCEP Certified Solar PV Installer NM ER-1J Journeyman Electrician Positive Energy, Inc. office: 575-524-2030 cell: 575-640-2432 westbr...@positiveenergysolar.com www.positiveenergysolar.com We definitely experienced an overstatement. We have a client who installed 5kW on a string inverter and 5kW on enphase and it is that side-by-side comparison that enabled us to positively identify a problem. There was a significant overstatement of output. We finally got a Enphase person who told us it was a software glitch. The problem appears to be fixed. They explained to us that our problem was isolated without giving us a detailed explanation of what happened. Since that problem was fixed, we have seen no difference in output between a string inverter and enphase. Randy Kirpal Khalsa wrote: This same issue has come up over the years for us..first with PV Powered inverters and then noticed in Fronius as well..We have noticed in most of our grid tied systems that are connected thru a "revenue grade meter" for Oregon Energy Trust production reporting, that the inverter always has a higher performance than indicated on the "utility grade meter". We have seen the discrepency as high as 10%. Over time this adds up to significant kWh differences. In our experience the inverter always has the higher kWh reporting, we have attributed this to the inverter wanting to report a good producti
[RE-wrenches] Enphase performance
So why is the Enphase 210 just limited "officially" to the Sanyo line? Thanks, marco Dana, Marco, Wrenches, In most locations, if the interest is in maximum lifetime energy production, it does make sense to use modules with STC power ratings significantly higher than the inverter max power rating. This is explained in the whitepaper located at: http://www.enphaseenergy.com/downloads/Enphase_White_Paper_Module_Rightsizin g.pdf Remember, under most real world conditions the module will not produce STC rated power. The inverter WILL produce maximum rated power plus some small percent to allow for the CEC max power test methods. Also, the module will produce less power every year (under the same conditions) and the inverter will produce its' max rated power for its' entire lifetime. By the way, this all applies to string, central, or microinverters. Of course, micros still retain the advantages of dealing with mismatch, partial shading/soiling, etc. Bottom line is, the "perfect" match will depend on your particular installation. See ya! Marv 707 763-4784 x7016 Dana Brandt wrote: Something to remember is that my simulation was for a specific location in Washington. The answer might be different for your location and weather patterns. I agree that it seems wrong to have the inverter rating 20% less than the array nameplate. Typically, I would consider that sort of pairing a poor design. You're right that there will certainly be some clipping - especially with cloud-edge effects. The real question in my mind is not whether the inverter will ever clip the output of the array, but what's the real impact of that on energy generation on an annual basis. This is what lead me to do the modeling simulations which indicated the effect is negligible when taken in the context of the total annual production. Compared to the whole year's sun, there just isn't that much energy in high production spikes like cloud edge effects that the inverters will clip - at least not around here. One thing to consider is that if you go with smaller modules you need more inverters. You might compare the cost of the additional inverters to the value of the 0.2% energy loss from clipping over the lifetime of the system. Dana Dana Brandt Ecotech Energy Systems, LLC www.ecotechenergy.com d...@ecotechenergy.com 360.510.0433 On Mon, May 10, 2010 at 11:36 AM, Marco Mangelsdorf wrote: I just don't understand why going over 20 percent of module nameplate to nameplate inverter rating makes any sense. I regularly see 120-130 percent of nameplate amperage coming off of the array on our office due to edge of cloud. So I have to disagree with Dana in this instance. I see this a bad design especially since lower output mods are so readily available these days. And what's up with the Enphase 210? Doesn't it say on their latest compatibility list (March 2010) that it's only good for the Sanyo line? What's up with that especially since I know that one other manufacturer is signing off on using the Enphase 210 with their 210-watt module, apparently with Enphase's approval? Marv-why is your Enphase 210 only listed for use with the Sanyo line when there's a growing number of 210+ watt mods out there these days? Thanks, marco I've been concerned about pairing higher wattage modules (~230W) with the 190W Enphase fearing a lot of clipping and power loss when the modules are at full power. I did some modeling of this setup in PVSYST and found that the expected loss from the inverter being underpowered is 0 - 0.2% annually depending on the assumptions. The modeling was for northwestern Washington State. A fifth of a percent seems pretty negligible to me and is easily offset by removing module mismatch from the equation. So, I'm convinced that matching modules in the 230W range with the 190W Enphase inverters is a good design. I recently installed 4kW of 230s with the Enphase 190s and have seen their output as high as 199W. Dana Dana Brandt Ecotech Energy Systems, LLC www.ecotechenergy.com d...@ecotechenergy.com 360.510.0433 On Fri, May 7, 2010 at 4:48 PM, Chris Worcester wrote: Do the Enphase inverters clip the output power to their rating like other manufacturer's? So a M190 can only put out 190 watts max? I have had this question for a bit now on system performances using Enphase in designs during our cold spring and fall days. Sincerely, Chris Worcester Solar Wind Works NABCEP Certified PV Installer Phone: 530-582-4503 Fax: 530-582-4603 www.solarwindworks.com <http://www.solarwindworks.com/> ch...@solarwindworks.com "Proven Energy Solutions" From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Westbrock Sent: Friday, May 07, 2010 10:33 AM To: RE-wrenches Subject: Re: [RE-wrenches] Enphase p
Re: [RE-wrenches] Enphase performance
Hi Marco, We definitely experienced an overstatment. We have a client who installed 5kW on a string inverter and 5kW on enphase and it is that side-by-side comparison that enabled us to positively identify a problem. There was a significant overstatement of output. We finally got a Enphase person who told us it was a software glitch. The problem appears to be fixed. They explained to us that our problem was isolated without giving us a detailed explanation of what happened. Since that problem was fixed, we have seen no difference in output between a string inverter and enphase. Randy Randy Sadewic Positive Energy Office: 505 424-1112 Cell:505 570-0137 From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Marco Mangelsdorf Sent: Thursday, May 06, 2010 8:25 PM To: 'RE-wrenches' Subject: [RE-wrenches] Enphase performance My biz partner has an Enphase system with BP Solar mods. He believes that the web-based monitoring system may be reporting on the high side as far as kWH performance over time. That is, he suspects that what he's seeing may not be accurate. Anyone out there have a similar experience? 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] Enphase performance
The over-reporting of energy that Randy refers to below was much higher than any discrepancy based on monitoring resolution. We have a pyranometer at the site, and Enphase reported energy production as high as 38% higher that predicted from irradiance data, as well as 38% higher than the string inverter portion of the same system. Individual microinverters showed instantaneous power output as high as 285 W from a nominal 190 W unit. Enphase explained that there was a software glitch that was resulting in "double counting". It took them over two months to correct this issue, time which is lost from our experimental comparison of string vs. microinverter. They indicated that this seemed to be an isolated situation, but I wonder how many Enphase customers are reporting miraculous performance from their system without verifying via another meter. Screen shot of a day's power production of 22 M190 microinverters (nominal 4180 watts AC): Mark Mark Westbrock NABCEP Certified Solar PV Installer NM ER-1J Journeyman Electrician Positive Energy, Inc. office: 575-524-2030 cell: 575-640-2432 westbr...@positiveenergysolar.com www.positiveenergysolar.com We definitely experienced an overstatement. We have a client who installed 5kW on a string inverter and 5kW on enphase and it is that side-by-side comparison that enabled us to positively identify a problem. There was a significant overstatement of output. We finally got a Enphase person who told us it was a software glitch. The problem appears to be fixed. They explained to us that our problem was isolated without giving us a detailed explanation of what happened. Since that problem was fixed, we have seen no difference in output between a string inverter and enphase. Randy Kirpal Khalsa wrote: This same issue has come up over the years for us..first with PV Powered inverters and then noticed in Fronius as well..We have noticed in most of our grid tied systems that are connected thru a "revenue grade meter" for Oregon Energy Trust production reporting, that the inverter always has a higher performance than indicated on the "utility grade meter". We have seen the discrepency as high as 10%. Over time this adds up to significant kWh differences. In our experience the inverter always has the higher kWh reporting, we have attributed this to the inverter wanting to report a good production number, to boost their efficiency claims..maybe even more than is accurate.I have asked PV Powered and Fronius about this and their line is that to put a "revenue grade meter" into the inverter would be cost prohibitive..interesting as the readily available revenue grade meters are only $30-$60. I would gladly pay that much extra if I didn't have to wire in an additional meter. I don't think this problem is unique to the Enphase units (i haven't installed any of these), I think all inverters should be required to install the revenue grade meters to give accurate reporting of actual production. Similar to how states have a "weights and scales" accuracy certification, energy consumption and production meters should be similarly calibratable. -- Sunny Regards, Kirpal Khalsa NABCEP Certified Solar PV Installer Renewable Energy Systems www.oregonsolarworks.com 541-218-0201 m 541-592-3958 o ___ 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] Enphase performance
Do the Enphase inverters clip the output power to their rating like other manufacturer's? So a M190 can only put out 190 watts max? I have had this question for a bit now on system performances using Enphase in designs during our cold spring and fall days. Sincerely, Chris Worcester Solar Wind Works NABCEP Certified PV Installer Phone: 530-582-4503 Fax: 530-582-4603 www.solarwindworks.com <http://www.solarwindworks.com/> ch...@solarwindworks.com "Proven Energy Solutions" From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Westbrock Sent: Friday, May 07, 2010 10:33 AM To: RE-wrenches Subject: Re: [RE-wrenches] Enphase performance The over-reporting of energy that Randy refers to below was much higher than any discrepancy based on monitoring resolution. We have a pyranometer at the site, and Enphase reported energy production as high as 38% higher that predicted from irradiance data, as well as 38% higher than the string inverter portion of the same system. Individual microinverters showed instantaneous power output as high as 285 W from a nominal 190 W unit. Enphase explained that there was a software glitch that was resulting in "double counting". It took them over two months to correct this issue, time which is lost from our experimental comparison of string vs. microinverter. They indicated that this seemed to be an isolated situation, but I wonder how many Enphase customers are reporting miraculous performance from their system without verifying via another meter. Screen shot of a day's power production of 22 M190 microinverters (nominal 4180 watts AC): Mark Mark Westbrock NABCEP Certified Solar PV Installer NM ER-1J Journeyman Electrician Positive Energy, Inc. office: 575-524-2030 cell: 575-640-2432 westbr...@positiveenergysolar.com www.positiveenergysolar.com We definitely experienced an overstatement. We have a client who installed 5kW on a string inverter and 5kW on enphase and it is that side-by-side comparison that enabled us to positively identify a problem. There was a significant overstatement of output. We finally got a Enphase person who told us it was a software glitch. The problem appears to be fixed. They explained to us that our problem was isolated without giving us a detailed explanation of what happened. Since that problem was fixed, we have seen no difference in output between a string inverter and enphase. Randy Kirpal Khalsa wrote: This same issue has come up over the years for us..first with PV Powered inverters and then noticed in Fronius as well..We have noticed in most of our grid tied systems that are connected thru a "revenue grade meter" for Oregon Energy Trust production reporting, that the inverter always has a higher performance than indicated on the "utility grade meter". We have seen the discrepency as high as 10%. Over time this adds up to significant kWh differences. In our experience the inverter always has the higher kWh reporting, we have attributed this to the inverter wanting to report a good production number, to boost their efficiency claims..maybe even more than is accurate.I have asked PV Powered and Fronius about this and their line is that to put a "revenue grade meter" into the inverter would be cost prohibitive..interesting as the readily available revenue grade meters are only $30-$60. I would gladly pay that much extra if I didn't have to wire in an additional meter. I don't think this problem is unique to the Enphase units (i haven't installed any of these), I think all inverters should be required to install the revenue grade meters to give accurate reporting of actual production. Similar to how states have a "weights and scales" accuracy certification, energy consumption and production meters should be similarly calibratable. -- Sunny Regards, Kirpal Khalsa NABCEP Certified Solar PV Installer Renewable Energy Systems www.oregonsolarworks.com 541-218-0201 m 541-592-3958 o _ ___ 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] Enphase performance
The "Maximum Output Power" listed on the M190 spec sheet is 190 watts. Upon observing output exceeding 190 watts, we questioned Enphase tech support and were told that the "actual" max output is 199 watts. Similarly, the actual max output for the M210 is reported to be 219 watts, although the spec sheet specifies 210 watts. This contradiction between "specified" and "actual" is troubling, both for proper overall system design and proper sizing of overcurrent protection, per 690.8(B)(1). Mark Westbrock NABCEP Certified Solar PV Installer NM ER-1J Journeyman Electrician Positive Energy, Inc. office: 575-524-2030 cell: 575-640-2432 westbr...@positiveenergysolar.com www.positiveenergysolar.com Chris Worcester wrote: Do the Enphase inverters clip the output power to their rating like other manufacturer’s? So a M190 can only put out 190 watts max? I have had this question for a bit now on system performances using Enphase in designs during our cold spring and fall days. Sincerely, Chris Worcester Solar Wind Works NABCEP Certified PV Installer Phone: 530-582-4503 Fax: 530-582-4603 www.solarwindworks.com ch...@solarwindworks.com "Proven Energy Solutions" From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Westbrock Sent: Friday, May 07, 2010 10:33 AM To: RE-wrenches Subject: Re: [RE-wrenches] Enphase performance The over-reporting of energy that Randy refers to below was much higher than any discrepancy based on monitoring resolution. We have a pyranometer at the site, and Enphase reported energy production as high as 38% higher that predicted from irradiance data, as well as 38% higher than the string inverter portion of the same system. Individual microinverters showed instantaneous power output as high as 285 W from a nominal 190 W unit. Enphase explained that there was a software glitch that was resulting in "double counting". It took them over two months to correct this issue, time which is lost from our experimental comparison of string vs. microinverter. They indicated that this seemed to be an isolated situation, but I wonder how many Enphase customers are reporting miraculous performance from their system without verifying via another meter. Screen shot of a day's power production of 22 M190 microinverters (nominal 4180 watts AC): Mark Mark Westbrock NABCEP Certified Solar PV Installer NM ER-1J Journeyman Electrician Positive Energy, Inc. office: 575-524-2030 cell: 575-640-2432 westbr...@positiveenergysolar.com www.positiveenergysolar.com We definitely experienced an overstatement. We have a client who installed 5kW on a string inverter and 5kW on enphase and it is that side-by-side comparison that enabled us to positively identify a problem. There was a significant overstatement of output. We finally got a Enphase person who told us it was a software glitch. The problem appears to be fixed. They explained to us that our problem was isolated without giving us a detailed explanation of what happened. Since that problem was fixed, we have seen no difference in output between a string inverter and enphase. Randy Kirpal Khalsa wrote: This same issue has come up over the years for us..first with PV Powered inverters and then noticed in Fronius as well..We have noticed in most of our grid tied systems that are connected thru a "revenue grade meter" for Oregon Energy Trust production reporting, that the inverter always has a higher performance than indicated on the "utility grade meter". We have seen the discrepency as high as 10%. Over time this adds up to significant kWh differences. In our experience the inverter always has the higher kWh reporting, we have attributed this to the inverter wanting to report a good production number, to boost their efficiency claims..maybe even more than is accurate.I have asked PV Powered and Fronius about this and their line is that to put a "revenue grade meter" into the inverter would be cost prohibitive..interesting as the readily available revenue grade meters are only $30-$60. I would gladly pay that much extra if I didn't have to wire in an additional meter. I don't think this problem is unique to the Enphase units (i haven't installed any of these), I think all inverters should be required to install the revenue grade meters to give accurate reporting of actual production. Similar to how states have a "weights and scales" accuracy certification, energy consumption and production meters should be similarly calibratable. -- Sunny Regards, Kirpal Khalsa NABCEP Certified Solar PV Installer Renewable Energy Systems www.oregonsolarworks.com 541-218-0201 m 541-592-3958 o
Re: [RE-wrenches] Enphase performance
The CEC max power tests require continuous output power monitoring for 180 minutes. At the end of the test, the CEC published power rating of the inverter is the manufacturer's stated max power OR the lowest power measured during the CEC test, whichever is lower. So, most manufacturers set the power limit slightly above their advertised max power, just to be sure that the CEC rating equals their desired power rating. An Enphase M190 Microinverter will typically limit power to 195W. So you are guaranteed 190W, but may see as high as 198W. Hope this helps! See ya! Marv 707 763-4784 x7016 Chris Worcester wrote: Do the Enphase inverters clip the output power to their rating like other manufacturer’s? So a M190 can only put out 190 watts max? I have had this question for a bit now on system performances using Enphase in designs during our cold spring and fall days. Sincerely, Chris Worcester Solar Wind Works NABCEP Certified PV Installer Phone: 530-582-4503 Fax: 530-582-4603 www.solarwindworks.com ch...@solarwindworks.com "Proven Energy Solutions" From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Westbrock Sent: Friday, May 07, 2010 10:33 AM To: RE-wrenches Subject: Re: [RE-wrenches] Enphase performance The over-reporting of energy that Randy refers to below was much higher than any discrepancy based on monitoring resolution. We have a pyranometer at the site, and Enphase reported energy production as high as 38% higher that predicted from irradiance data, as well as 38% higher than the string inverter portion of the same system. Individual microinverters showed instantaneous power output as high as 285 W from a nominal 190 W unit. Enphase explained that there was a software glitch that was resulting in "double counting". It took them over two months to correct this issue, time which is lost from our experimental comparison of string vs. microinverter. They indicated that this seemed to be an isolated situation, but I wonder how many Enphase customers are reporting miraculous performance from their system without verifying via another meter. Screen shot of a day's power production of 22 M190 microinverters (nominal 4180 watts AC): Mark Mark Westbrock NABCEP Certified Solar PV Installer NM ER-1J Journeyman Electrician Positive Energy, Inc. office: 575-524-2030 cell: 575-640-2432 westbr...@positiveenergysolar.com www.positiveenergysolar.com We definitely experienced an overstatement. We have a client who installed 5kW on a string inverter and 5kW on enphase and it is that side-by-side comparison that enabled us to positively identify a problem. There was a significant overstatement of output. We finally got a Enphase person who told us it was a software glitch. The problem appears to be fixed. They explained to us that our problem was isolated without giving us a detailed explanation of what happened. Since that problem was fixed, we have seen no difference in output between a string inverter and enphase. Randy Kirpal Khalsa wrote: This same issue has come up over the years for us..first with PV Powered inverters and then noticed in Fronius as well..We have noticed in most of our grid tied systems that are connected thru a "revenue grade meter" for Oregon Energy Trust production reporting, that the inverter always has a higher performance than indicated on the "utility grade meter". We have seen the discrepency as high as 10%. Over time this adds up to significant kWh differences. In our experience the inverter always has the higher kWh reporting, we have attributed this to the inverter wanting to report a good production number, to boost their efficiency claims..maybe even more than is accurate.I have asked PV Powered and Fronius about this and their line is that to put a "revenue grade meter" into the inverter would be cost prohibitive..interesting as the readily available revenue grade meters are only $30-$60. I would gladly pay that much extra if I didn't have to wire in an additional meter. I don't think this problem is unique to the Enphase units (i haven't installed any of these), I think all inverters should be required to install the revenue grade meters to give accurate reporting of actual production. Similar to how states have a "weights and scales" accuracy certification, energy consumption and production meters should be similarly calibratable. -- Sunny Regards, Kirpal Khalsa NABCEP Certified Solar PV Installer Renewable Energy Systems www.oregonsolarworks.com 541-218-0201 m 541-592-3958 o ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Optio
Re: [RE-wrenches] Enphase performance
This should not be troubling at all. It is very straight forward. Because there is only one module per inverter, and the conductors are sized for all possible overcurrent conditions, no further consideration is necessary for the DC side of the circuit. For the ac side, section 690.8(A)(3) applies. "Inverter Output Circuit Current. The maximum current shall be the inverter continuous output current rating." So, for an M190-240 this is 0.8A. A fully loaded branch of 15 inverters is 12A, times 1.25 yields a 15A breaker. Do you think we should provide more documentation on this subject? All suggestions for improved documentation, whitepapers, app notes, etc. are very welcome. See ya! Marv 707 763-4784 x7016 Mark Westbrock wrote: The "Maximum Output Power" listed on the M190 spec sheet is 190 watts. Upon observing output exceeding 190 watts, we questioned Enphase tech support and were told that the "actual" max output is 199 watts. Similarly, the actual max output for the M210 is reported to be 219 watts, although the spec sheet specifies 210 watts. This contradiction between "specified" and "actual" is troubling, both for proper overall system design and proper sizing of overcurrent protection, per 690.8(B)(1). Mark Westbrock NABCEP Certified Solar PV Installer NM ER-1J Journeyman Electrician Positive Energy, Inc. office: 575-524-2030 cell: 575-640-2432 westbr...@positiveenergysolar.com www.positiveenergysolar.com Chris Worcester wrote: Do the Enphase inverters clip the output power to their rating like other manufacturer’s? So a M190 can only put out 190 watts max? I have had this question for a bit now on system performances using Enphase in designs during our cold spring and fall days. Sincerely, Chris Worcester Solar Wind Works NABCEP Certified PV Installer Phone: 530-582-4503 Fax: 530-582-4603 www.solarwindworks.com ch...@solarwindworks.com "Proven Energy Solutions" From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Westbrock Sent: Friday, May 07, 2010 10:33 AM To: RE-wrenches Subject: Re: [RE-wrenches] Enphase performance The over-reporting of energy that Randy refers to below was much higher than any discrepancy based on monitoring resolution. We have a pyranometer at the site, and Enphase reported energy production as high as 38% higher that predicted from irradiance data, as well as 38% higher than the string inverter portion of the same system. Individual microinverters showed instantaneous power output as high as 285 W from a nominal 190 W unit. Enphase explained that there was a software glitch that was resulting in "double counting". It took them over two months to correct this issue, time which is lost from our experimental comparison of string vs. microinverter. They indicated that this seemed to be an isolated situation, but I wonder how many Enphase customers are reporting miraculous performance from their system without verifying via another meter. Screen shot of a day's power production of 22 M190 microinverters (nominal 4180 watts AC): Mark Mark Westbrock NABCEP Certified Solar PV Installer NM ER-1J Journeyman Electrician Positive Energy, Inc. office: 575-524-2030 cell: 575-640-2432 westbr...@positiveenergysolar.com www.positiveenergysolar.com We definitely experienced an overstatement. We have a client who installed 5kW on a string inverter and 5kW on enphase and it is that side-by-side comparison that enabled us to positively identify a problem. There was a significant overstatement of output. We finally got a Enphase person who told us it was a software glitch. The problem appears to be fixed. They explained to us that our problem was isolated without giving us a detailed explanation of what happened. Since that problem was fixed, we have seen no difference in output between a string inverter and enphase. Randy Kirpal Khalsa wrote: This same issue has come up over the years for us..first with PV Powered inverters and then noticed in Fronius as well..We have noticed in most of our grid tied systems that are connected thru a "revenue grade meter" for Oregon Energy Trust production reporting, that the inverter always has a higher performance than indicated on the "utility grade meter". We have seen the discrepency as high as 10%. Over time this adds up to significant kWh differences. In our experience the inverter always has the higher kWh reporting, we have attributed this to the inverter wanting to report a good production number, to boost their efficiency claims..maybe even more than is accurate.I have asked PV Powered and Fronius a
Re: [RE-wrenches] Enphase performance
I've been concerned about pairing higher wattage modules (~230W) with the 190W Enphase fearing a lot of clipping and power loss when the modules are at full power. I did some modeling of this setup in PVSYST and found that the expected loss from the inverter being underpowered is 0 - 0.2% annually depending on the assumptions. The modeling was for northwestern Washington State. A fifth of a percent seems pretty negligible to me and is easily offset by removing module mismatch from the equation. So, I'm convinced that matching modules in the 230W range with the 190W Enphase inverters is a good design. I recently installed 4kW of 230s with the Enphase 190s and have seen their output as high as 199W. Dana Dana Brandt Ecotech Energy Systems, LLC www.ecotechenergy.com d...@ecotechenergy.com 360.510.0433 On Fri, May 7, 2010 at 4:48 PM, Chris Worcester wrote: > Do the Enphase inverters clip the output power to their rating like other > manufacturer’s? So a M190 can only put out 190 watts max? I have had this > question for a bit now on system performances using Enphase in designs > during our cold spring and fall days. > > > > Sincerely, > > Chris Worcester > > Solar Wind Works > NABCEP Certified PV Installer > Phone: 530-582-4503 > Fax: 530-582-4603 > www.solarwindworks.com > ch...@solarwindworks.com > "Proven Energy Solutions" > > > > *From:* re-wrenches-boun...@lists.re-wrenches.org [mailto: > re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Mark Westbrock > *Sent:* Friday, May 07, 2010 10:33 AM > *To:* RE-wrenches > *Subject:* Re: [RE-wrenches] Enphase performance > > > > The over-reporting of energy that Randy refers to below was much higher > than any discrepancy based on monitoring resolution. We have a pyranometer > at the site, and Enphase reported energy production as high as 38% higher > that predicted from irradiance data, as well as 38% higher than the string > inverter portion of the same system. Individual microinverters showed > instantaneous power output as high as 285 W from a nominal 190 W unit. > > Enphase explained that there was a software glitch that was resulting in > "double counting". It took them over two months to correct this issue, time > which is lost from our experimental comparison of string vs. microinverter. > They indicated that this seemed to be an isolated situation, but I wonder > how many Enphase customers are reporting miraculous performance from their > system without verifying via another meter. > > Screen shot of a day's power production of 22 M190 microinverters (nominal > 4180 watts AC): > > > Mark > > Mark Westbrock > > NABCEP Certified Solar PV Installer > > NM ER-1J Journeyman Electrician > > Positive Energy, Inc. > > office: 575-524-2030 > > cell: 575-640-2432 > > westbr...@positiveenergysolar.com > > www.positiveenergysolar.com > > > > We definitely experienced an overstatement. > > > > We have a client who installed 5kW on a string inverter and 5kW on enphase > and it is that side-by-side comparison that enabled us to positively > identify a problem. There was a significant overstatement of output. We > finally got a Enphase person who told us it was a software glitch. The > problem appears to be fixed. They explained to us that our problem was > isolated without giving us a detailed explanation of what happened. Since > that problem was fixed, we have seen no difference in output between a > string inverter and enphase. > > > > Randy > > Kirpal Khalsa wrote: > > This same issue has come up over the years for us..first with PV > Powered inverters and then noticed in Fronius as well..We have noticed > in most of our grid tied systems that are connected thru a "revenue grade > meter" for Oregon Energy Trust production reporting, that the inverter > always has a higher performance than indicated on the "utility grade > meter". We have seen the discrepency as high as 10%. Over time this adds > up to significant kWh differences. In our experience the inverter always > has the higher kWh reporting, we have attributed this to the inverter > wanting to report a good production number, to boost their efficiency > claims..maybe even more than is accurate.I have asked PV Powered and > Fronius about this and their line is that to put a "revenue grade meter" > into the inverter would be cost prohibitive..interesting as the readily > available revenue grade meters are only $30-$60. I would gladly pay that > much extra if I didn't have to wire in an additional meter. > I don't think this problem is unique to the Enphase units (i haven't &g
Re: [RE-wrenches] Enphase performance
Something to remember is that my simulation was for a specific location in Washington. The answer might be different for your location and weather patterns. I agree that it seems wrong to have the inverter rating 20% less than the array nameplate. Typically, I would consider that sort of pairing a poor design. You're right that there will certainly be some clipping - especially with cloud-edge effects. The real question in my mind is not whether the inverter will ever clip the output of the array, but what's the real impact of that on energy generation on an annual basis. This is what lead me to do the modeling simulations which indicated the effect is negligible when taken in the context of the total annual production. Compared to the whole year's sun, there just isn't that much energy in high production spikes like cloud edge effects that the inverters will clip - at least not around here. One thing to consider is that if you go with smaller modules you need more inverters. You might compare the cost of the additional inverters to the value of the 0.2% energy loss from clipping over the lifetime of the system. Dana Dana Brandt Ecotech Energy Systems, LLC www.ecotechenergy.com d...@ecotechenergy.com 360.510.0433 On Mon, May 10, 2010 at 11:36 AM, Marco Mangelsdorf wrote: > I just don’t understand why going over 20 percent of module nameplate to > nameplate inverter rating makes any sense. > > > > I regularly see 120-130 percent of nameplate amperage coming off of the > array on our office due to edge of cloud. > > > > So I have to disagree with Dana in this instance. I see this a bad design > especially since lower output mods are so readily available these days. > > > > And what’s up with the Enphase 210? Doesn’t it say on their latest > compatibility list (March 2010) that it’s only good for the Sanyo line? > What’s up with that especially since I know that one other manufacturer is > signing off on using the Enphase 210 with their 210-watt module, apparently > with Enphase’s approval? > > > > Marv—why is your Enphase 210 only listed for use with the Sanyo line when > there’s a growing number of 210+ watt mods out there these days? > > > > Thanks, > > marco > > > > I've been concerned about pairing higher wattage modules (~230W) with the > 190W Enphase fearing a lot of clipping and power loss when the modules are > at full power. > > I did some modeling of this setup in PVSYST and found that the expected > loss from the inverter being underpowered is 0 - 0.2% annually depending on > the assumptions. The modeling was for northwestern Washington State. A fifth > of a percent seems pretty negligible to me and is easily offset by removing > module mismatch from the equation. So, I'm convinced that matching modules > in the 230W range with the 190W Enphase inverters is a good design. > > I recently installed 4kW of 230s with the Enphase 190s and have seen their > output as high as 199W. > > Dana > > > Dana Brandt > Ecotech Energy Systems, LLC > www.ecotechenergy.com > d...@ecotechenergy.com > 360.510.0433 > > On Fri, May 7, 2010 at 4:48 PM, Chris Worcester > wrote: > > Do the Enphase inverters clip the output power to their rating like other > manufacturer’s? So a M190 can only put out 190 watts max? I have had this > question for a bit now on system performances using Enphase in designs > during our cold spring and fall days. > > > > Sincerely, > > Chris Worcester > > Solar Wind Works > NABCEP Certified PV Installer > Phone: 530-582-4503 > Fax: 530-582-4603 > www.solarwindworks.com > ch...@solarwindworks.com > "Proven Energy Solutions" > > > > *From:* re-wrenches-boun...@lists.re-wrenches.org [mailto: > re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Mark Westbrock > *Sent:* Friday, May 07, 2010 10:33 AM > *To:* RE-wrenches > *Subject:* Re: [RE-wrenches] Enphase performance > > > > The over-reporting of energy that Randy refers to below was much higher > than any discrepancy based on monitoring resolution. We have a pyranometer > at the site, and Enphase reported energy production as high as 38% higher > that predicted from irradiance data, as well as 38% higher than the string > inverter portion of the same system. Individual microinverters showed > instantaneous power output as high as 285 W from a nominal 190 W unit. > > Enphase explained that there was a software glitch that was resulting in > "double counting". It took them over two months to correct this issue, time > which is lost from our experimental comparison of string vs. microinverter. > They indicated that this seemed to be an isolated situation, but I wonder > how
Re: [RE-wrenches] Enphase performance
On Behalf Of Mark Westbrock Sent: Friday, May 07, 2010 10:33 AM To: RE-wrenches Subject: Re: [RE-wrenches] Enphase performance The over-reporting of energy that Randy refers to below was much higher than any discrepancy based on monitoring resolution. We have a pyranometer at the site, and Enphase reported energy production as high as 38% higher that predicted from irradiance data, as well as 38% higher than the string inverter portion of the same system. Individual microinverters showed instantaneous power output as high as 285 W from a nominal 190 W unit. Enphase explained that there was a software glitch that was resulting in "double counting". It took them over two months to correct this issue, time which is lost from our experimental comparison of string vs. microinverter. They indicated that this seemed to be an isolated situation, but I wonder how many Enphase customers are reporting miraculous performance from their system without verifying via another meter. Screen shot of a day's power production of 22 M190 microinverters (nominal 4180 watts AC): Error! Filename not specified. Mark Mark Westbrock NABCEP Certified Solar PV Installer NM ER-1J Journeyman Electrician Positive Energy, Inc. office: 575-524-2030 cell: 575-640-2432 westbr...@positiveenergysolar.com www.positiveenergysolar.com We definitely experienced an overstatement. We have a client who installed 5kW on a string inverter and 5kW on enphase and it is that side-by-side comparison that enabled us to positively identify a problem. There was a significant overstatement of output. We finally got a Enphase person who told us it was a software glitch. The problem appears to be fixed. They explained to us that our problem was isolated without giving us a detailed explanation of what happened. Since that problem was fixed, we have seen no difference in output between a string inverter and enphase. Randy Kirpal Khalsa wrote: This same issue has come up over the years for us..first with PV Powered inverters and then noticed in Fronius as well..We have noticed in most of our grid tied systems that are connected thru a "revenue grade meter" for Oregon Energy Trust production reporting, that the inverter always has a higher performance than indicated on the "utility grade meter". We have seen the discrepency as high as 10%. Over time this adds up to significant kWh differences. In our experience the inverter always has the higher kWh reporting, we have attributed this to the inverter wanting to report a good production number, to boost their efficiency claims..maybe even more than is accurate.I have asked PV Powered and Fronius about this and their line is that to put a "revenue grade meter" into the inverter would be cost prohibitive..interesting as the readily available revenue grade meters are only $30-$60. I would gladly pay that much extra if I didn't have to wire in an additional meter. I don't think this problem is unique to the Enphase units (i haven't installed any of these), I think all inverters should be required to install the revenue grade meters to give accurate reporting of actual production. Similar to how states have a "weights and scales" accuracy certification, energy consumption and production meters should be similarly calibratable. -- Sunny Regards, Kirpal Khalsa NABCEP Certified Solar PV Installer Renewable Energy Systems www.oregonsolarworks.com 541-218-0201 m 541-592-3958 o ___ 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 No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.819 / Virus Database: 271.1.1/2864 - Release Date: 05/09/10 08:26:00 _
Re: [RE-wrenches] Enphase performance
I recently installed 4kW of 230s with the Enphase 190s and have seen their output as high as 199W. Dana Dana Brandt Ecotech Energy Systems, LLC www.ecotechenergy.com d...@ecotechenergy.com 360.510.0433 On Fri, May 7, 2010 at 4:48 PM, Chris Worcester <ch...@solarwindworks.com> wrote: Do the Enphase inverters clip the output power to their rating like other manufacturer’s? So a M190 can only put out 190 watts max? I have had this question for a bit now on system performances using Enphase in designs during our cold spring and fall days. Sincerely, Chris Worcester Solar Wind Works NABCEP Certified PV Installer Phone: 530-582-4503 Fax: 530-582-4603 www.solarwindworks.com ch...@solarwindworks.com "Proven Energy Solutions" From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Westbrock Sent: Friday, May 07, 2010 10:33 AM To: RE-wrenches Subject: Re: [RE-wrenches] Enphase performance The over-reporting of energy that Randy refers to below was much higher than any discrepancy based on monitoring resolution. We have a pyranometer at the site, and Enphase reported energy production as high as 38% higher that predicted from irradiance data, as well as 38% higher than the string inverter portion of the same system. Individual microinverters showed instantaneous power output as high as 285 W from a nominal 190 W unit. Enphase explained that there was a software glitch that was resulting in "double counting". It took them over two months to correct this issue, time which is lost from our experimental comparison of string vs. microinverter. They indicated that this seemed to be an isolated situation, but I wonder how many Enphase customers are reporting miraculous performance from their system without verifying via another meter. Screen shot of a day's power production of 22 M190 microinverters (nominal 4180 watts AC): Error! Filename not specified. Mark Mark Westbrock NABCEP Certified Solar PV Installer NM ER-1J Journeyman Electrician Positive Energy, Inc. office: 575-524-2030 cell: 575-640-2432 westbr...@positiveenergysolar.com www.positiveenergysolar.com We definitely experienced an overstatement. We have a client who installed 5kW on a string inverter and 5kW on enphase and it is that side-by-side comparison that enabled us to positively identify a problem. There was a significant overstatement of output. We finally got a Enphase person who told us it was a software glitch. The problem appears to be fixed. They explained to us that our problem was isolated without giving us a detailed explanation of what happened. Since that problem was fixed, we have seen no difference in output between a string inverter and enphase. Randy Kirpal Khalsa wrote: This same issue has come up over the years for us..first with PV Powered inverters and then noticed in Fronius as well..We have noticed in most of our grid tied systems that are connected thru a "revenue grade meter" for Oregon Energy Trust production reporting, that the inverter always has a higher performance than indicated on the "utility grade meter". We have seen the discrepency as high as 10%. Over time this adds up to significant kWh differences. In our experience the inverter always has the higher kWh reporting, we have attributed this to the inverter wanting to report a good production number, to boost their efficiency claims..maybe even more than is accurate.I have asked PV Powered and Fronius about this and their line is that to put a "revenue grade meter" into the inverter would be cost prohibitive..interesting as the readily available revenue grade meters are only $30-$60. I would gladly pay that much extra if I didn't have to wire in an additional meter. I don't think this problem is unique to the Enphase units (i haven't installed any of these), I think all inverters should be required to install the revenue grade meters to give accurate reporting of actual production. Similar to how states have a "weights and scales" accuracy certification, energy consumption and production meters should be similarly calibratable. -- Sunny Regards, Kirpal Khalsa NABCEP Certified Solar PV Installer Renewable Energy Systems www.oregonsolarworks.com 541-218-0201 m 541-592-3958 o ___ 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: [RE-wrenches] Enphase performance
Hi Marv, In our experience, there are a couple of things you didn't mention that can make a big difference. The mounting approach can affect the delta T ambient-module temperature resulting in much higher output for groundmounts, polemounts, or rooftop arrays in windy ridges or open spaces. Second, we regularly get irradiance above 1000W/m2 in our area. So your statement "depends on the particular installation" is a very important point. Randy Randy Sadewic Positive Energy Office: 505 424-1112 Cell:505 570-0137 From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Marv Dargatz Sent: Monday, May 10, 2010 3:59 PM To: RE-wrenches Subject: Re: [RE-wrenches] Enphase performance Marco, Sorry, I missed that question in the previous e-mail. A couple of points about the compatibility list: 1. We include only modules that have passed our internal math check for compatibility over the temperature range of the inverter. 2. If the module manufacturer objects to being on the compatibility list, we will not include them. Sunpower has objected, so they are not on the list. Zhejiang Wanxiang Solar Co. Ltd is also shown as compatible with the M210. The list is only a guideline. Any module that falls within the voltage spec over the expected operating temperature range of the installation, and does not exceed the inverter DC input short circuit current rating is certainly a valid combination, and the inverter is fully warranted. Notice that module power rating is not a factor here. I hope this helps. See ya! Marv 707 763-4784 x7016 Marco Mangelsdorf wrote: So why is the Enphase 210 just limited "officially" to the Sanyo line? Thanks, marco Dana, Marco, Wrenches, In most locations, if the interest is in maximum lifetime energy production, it does make sense to use modules with STC power ratings significantly higher than the inverter max power rating. This is explained in the whitepaper located at: http://www.enphaseenergy.com/downloads/Enphase_White_Paper_Module_Rightsizin g.pdf Remember, under most real world conditions the module will not produce STC rated power. The inverter WILL produce maximum rated power plus some small percent to allow for the CEC max power test methods. Also, the module will produce less power every year (under the same conditions) and the inverter will produce its' max rated power for its' entire lifetime. By the way, this all applies to string, central, or microinverters. Of course, micros still retain the advantages of dealing with mismatch, partial shading/soiling, etc. Bottom line is, the "perfect" match will depend on your particular installation. See ya! Marv 707 763-4784 x7016 Dana Brandt wrote: Something to remember is that my simulation was for a specific location in Washington. The answer might be different for your location and weather patterns. I agree that it seems wrong to have the inverter rating 20% less than the array nameplate. Typically, I would consider that sort of pairing a poor design. You're right that there will certainly be some clipping - especially with cloud-edge effects. The real question in my mind is not whether the inverter will ever clip the output of the array, but what's the real impact of that on energy generation on an annual basis. This is what lead me to do the modeling simulations which indicated the effect is negligible when taken in the context of the total annual production. Compared to the whole year's sun, there just isn't that much energy in high production spikes like cloud edge effects that the inverters will clip - at least not around here. One thing to consider is that if you go with smaller modules you need more inverters. You might compare the cost of the additional inverters to the value of the 0.2% energy loss from clipping over the lifetime of the system. Dana Dana Brandt Ecotech Energy Systems, LLC www.ecotechenergy.com d...@ecotechenergy.com 360.510.0433 On Mon, May 10, 2010 at 11:36 AM, Marco Mangelsdorf wrote: I just don't understand why going over 20 percent of module nameplate to nameplate inverter rating makes any sense. I regularly see 120-130 percent of nameplate amperage coming off of the array on our office due to edge of cloud. So I have to disagree with Dana in this instance. I see this a bad design especially since lower output mods are so readily available these days. And what's up with the Enphase 210? Doesn't it say on their latest compatibility list (March 2010) that it's only good for the Sanyo line? What's up with that especially since I know that one other manufacturer is signing off on using the Enphase 210 with their 210-watt module, apparently with Enphase's approval? Marv-why is your Enphase 210 only listed for use with the Sanyo line when there's a gro
Re: [RE-wrenches] Enphase performance
Marv, What would be a (or more) reason(s) that the module manufacturer wouldn't want to be on your approved list (and sell more modules)? Thank you, Bill Loesch Solar 1 - Saint Louis Solar - Original Message - From: Marv Dargatz To: RE-wrenches Sent: Monday, May 10, 2010 4:59 PM Subject: Re: [RE-wrenches] Enphase performance Marco, Sorry, I missed that question in the previous e-mail. A couple of points about the compatibility list: 1. We include only modules that have passed our internal math check for compatibility over the temperature range of the inverter. 2. If the module manufacturer objects to being on the compatibility list, we will not include them. Sunpower has objected, so they are not on the list. Zhejiang Wanxiang Solar Co. Ltd is also shown as compatible with the M210. The list is only a guideline. Any module that falls within the voltage spec over the expected operating temperature range of the installation, and does not exceed the inverter DC input short circuit current rating is certainly a valid combination, and the inverter is fully warranted. Notice that module power rating is not a factor here. I hope this helps. See ya! Marv 707 763-4784 x7016 Marco Mangelsdorf wrote: So why is the Enphase 210 just limited "officially" to the Sanyo line? Thanks, marco Dana, Marco, Wrenches, In most locations, if the interest is in maximum lifetime energy production, it does make sense to use modules with STC power ratings significantly higher than the inverter max power rating. This is explained in the whitepaper located at: http://www.enphaseenergy.com/downloads/Enphase_White_Paper_Module_Rightsizing.pdf Remember, under most real world conditions the module will not produce STC rated power. The inverter WILL produce maximum rated power plus some small percent to allow for the CEC max power test methods. Also, the module will produce less power every year (under the same conditions) and the inverter will produce its' max rated power for its' entire lifetime. By the way, this all applies to string, central, or microinverters. Of course, micros still retain the advantages of dealing with mismatch, partial shading/soiling, etc. Bottom line is, the "perfect" match will depend on your particular installation. See ya! Marv707 763-4784 x7016 Dana Brandt wrote: Something to remember is that my simulation was for a specific location in Washington. The answer might be different for your location and weather patterns. I agree that it seems wrong to have the inverter rating 20% less than the array nameplate. Typically, I would consider that sort of pairing a poor design. You're right that there will certainly be some clipping - especially with cloud-edge effects. The real question in my mind is not whether the inverter will ever clip the output of the array, but what's the real impact of that on energy generation on an annual basis. This is what lead me to do the modeling simulations which indicated the effect is negligible when taken in the context of the total annual production. Compared to the whole year's sun, there just isn't that much energy in high production spikes like cloud edge effects that the inverters will clip - at least not around here. One thing to consider is that if you go with smaller modules you need more inverters. You might compare the cost of the additional inverters to the value of the 0.2% energy loss from clipping over the lifetime of the system. Dana Dana Brandt Ecotech Energy Systems, LLC www.ecotechenergy.com d...@ecotechenergy.com 360.510.0433 On Mon, May 10, 2010 at 11:36 AM, Marco Mangelsdorf wrote: I just don't understand why going over 20 percent of module nameplate to nameplate inverter rating makes any sense. I regularly see 120-130 percent of nameplate amperage coming off of the array on our office due to edge of cloud. So I have to disagree with Dana in this instance. I see this a bad design especially since lower output mods are so readily available these days. And what's up with the Enphase 210? Doesn't it say on their latest compatibility list (March 2010) that it's only good for the Sanyo line? What's up with that especially since I know that one other manufacturer is signing off on using the Enphase 210 with their 210-watt module, apparently with Enphase's approval? Marv-why is your Enphase 210 only listed for use with the Sanyo line when there's a growing number of 210+ watt mods out there these days? Thanks, marco I've been concerned about pairing higher wattage modules (~230W) with the 190W Enphase fearing a lot of clipping and power loss when the modules are at full power. I did
Re: [RE-wrenches] Enphase performance
Bill,
Sunpower likes to sell overpriced, private labeled inverters along with
their modules. The make installers who want to use their modules, but
"Sunpower" inverters.
David
David Katz
Chief Technical Officer
AEE Solar
1155 Redway Drive
P.O. Box 339
Redway, CA 95560
Tel (707) 825-1200
Fax (707) 825-1202
dk...@aeesolar.com <mailto:da...@aeesolar.com>
www.aeesolar.com <http://www.aeesolar.com/>
DISCLAIMER:
This communication, along with any documents, files or attachments, is
intended for the use of only the addressee and contains privileged and
confidential information. If you are not the intended recipient, you are
hereby notified that any dissemination, distribution or copying of any
information contained in or attached to this communication is strictly
prohibited. If you have received this message in error, please notify
the sender immediately by e-mail reply and destroy the original
communication and its attachments without reading, printing or saving in
any manner.
Bill Loesch wrote:
Marv,
What would be a (or more) reason(s) that the module manufacturer
wouldn't want to be on your approved list (and sell more modules)?
Thank you,
Bill Loesch
Solar 1 - Saint Louis Solar
- Original Message -
*From:* Marv Dargatz <mailto:mdarg...@enphaseenergy.com>
*To:* RE-wrenches <mailto:re-wrenches@lists.re-wrenches.org>
*Sent:* Monday, May 10, 2010 4:59 PM
*Subject:* Re: [RE-wrenches] Enphase performance
Marco,
Sorry, I missed that question in the previous e-mail.
A couple of points about the compatibility list:
1. We include only modules that have passed our internal math
check for compatibility over the temperature range of the inverter.
2. If the module manufacturer objects to being on the
compatibility list, we will not include them.
Sunpower has objected, so they are not on the list.
Zhejiang Wanxiang Solar Co. Ltd is also shown as compatible with
the M210.
The list is only a guideline. Any module that falls within the
voltage spec over the expected operating temperature range of the
installation, and does not exceed the inverter DC input short
circuit current rating is certainly a valid combination, and the
inverter is fully warranted. Notice that module power rating is
not a factor here.
I hope this helps.
See ya!
Marv
707 763-4784 x7016
Marco Mangelsdorf wrote:
So why is the Enphase 210 just limited "officially" to the Sanyo
line?
Thanks,
marco
Dana, Marco, Wrenches,
In most locations, if the interest is in maximum lifetime energy
production, it does make sense to use modules with STC power
ratings significantly higher than the inverter max power rating.
This is explained in the whitepaper located at:
http://www.enphaseenergy.com/downloads/Enphase_White_Paper_Module_Rightsizing.pdf
Remember, under most real world conditions the module will not
produce STC rated power. The inverter WILL produce maximum rated
power plus some small percent to allow for the CEC max power test
methods. Also, the module will produce less power every year
(under the same conditions) and the inverter will produce its'
max rated power for its' entire lifetime.
By the way, this all applies to string, central, or
microinverters. Of course, micros still retain the advantages of
dealing with mismatch, partial shading/soiling, etc.
Bottom line is, the "perfect" match will depend on your
particular installation.
See ya!
Marv
707 763-4784 x7016
Dana Brandt wrote:
Something to remember is that my simulation was for a specific
location in Washington. The answer might be different for your
location and weather patterns.
I agree that it seems wrong to have the inverter rating 20% less
than the array nameplate. Typically, I would consider that sort
of pairing a poor design. You're right that there will certainly
be some clipping - especially with cloud-edge effects. The real
question in my mind is not whether the inverter will ever clip
the output of the array, but what's the real impact of that on
energy generation on an annual basis. This is what lead me to do
the modeling simulations which indicated the effect is negligible
when taken in the context of the total annual production.
Compared to the whole year's sun, there just isn't that much
energy in high production spikes like cloud edge effects that the
inverters will clip - at least not around here.
One thing to consider is that if you go with smaller modules you
need more inverters. You might compare the cost of the additional
inverters to the value of the 0.2% energy loss from clipping over
Re: [RE-wrenches] Enphase performance
Hi Randy, What are the best ways to mount the inverters to increase the output? Thanks At 06:49 PM 5/10/2010, you wrote: The mounting approach can affect the delta T ambient-module temperature resulting in much higher output for groundmounts, polemounts, or rooftop arrays in windy ridges or open spaces. Drake Chamberlin Athens Electric OH License 44810 CO License 3773 NABCEP TM Certified PV Installer Office - 740-448-7328 Mobile - 740-856-9648 ___ 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] Enphase performance
Thanks, Randy. You're absolutely right. Cell temperature is one of the big driving factors, and air circulation around the module definitely affects cell temperature. Your second point about cloud enhancement is also well taken. It always comes down to analyzing the specific conditions for each installation. And that's why they pay you the big bucks! Right? ;-) See ya! Marv 707 763-4784 x7016 Randy wrote: Hi Marv, In our experience, there are a couple of things you didn’t mention that can make a big difference. The mounting approach can affect the delta T ambient-module temperature resulting in much higher output for groundmounts, polemounts, or rooftop arrays in windy ridges or open spaces. Second, we regularly get irradiance above 1000W/m2 in our area. So your statement “depends on the particular installation” is a very important point. Randy Randy Sadewic Positive Energy Office: 505 424-1112 Cell: 505 570-0137 From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Marv Dargatz Sent: Monday, May 10, 2010 3:59 PM To: RE-wrenches Subject: Re: [RE-wrenches] Enphase performance Marco, Sorry, I missed that question in the previous e-mail. A couple of points about the compatibility list: 1. We include only modules that have passed our internal math check for compatibility over the temperature range of the inverter. 2. If the module manufacturer objects to being on the compatibility list, we will not include them. Sunpower has objected, so they are not on the list. Zhejiang Wanxiang Solar Co. Ltd is also shown as compatible with the M210. The list is only a guideline. Any module that falls within the voltage spec over the expected operating temperature range of the installation, and does not exceed the inverter DC input short circuit current rating is certainly a valid combination, and the inverter is fully warranted. Notice that module power rating is not a factor here. I hope this helps. See ya! Marv 707 763-4784 x7016 Marco Mangelsdorf wrote: So why is the Enphase 210 just limited “officially” to the Sanyo line? Thanks, marco Dana, Marco, Wrenches, In most locations, if the interest is in maximum lifetime energy production, it does make sense to use modules with STC power ratings significantly higher than the inverter max power rating. This is explained in the whitepaper located at: http://www.enphaseenergy.com/downloads/Enphase_White_Paper_Module_Rightsizing.pdf Remember, under most real world conditions the module will not produce STC rated power. The inverter WILL produce maximum rated power plus some small percent to allow for the CEC max power test methods. Also, the module will produce less power every year (under the same conditions) and the inverter will produce its' max rated power for its' entire lifetime. By the way, this all applies to string, central, or microinverters. Of course, micros still retain the advantages of dealing with mismatch, partial shading/soiling, etc. Bottom line is, the "perfect" match will depend on your particular installation. See ya! Marv 707 763-4784 x7016 Dana Brandt wrote: Something to remember is that my simulation was for a specific location in Washington. The answer might be different for your location and weather patterns. I agree that it seems wrong to have the inverter rating 20% less than the array nameplate. Typically, I would consider that sort of pairing a poor design. You're right that there will certainly be some clipping - especially with cloud-edge effects. The real question in my mind is not whether the inverter will ever clip the output of the array, but what's the real impact of that on energy generation on an annual basis. This is what lead me to do the modeling simulations which indicated the effect is negligible when taken in the context of the total annual production. Compared to the whole year's sun, there just isn't that much energy in high production spikes like cloud edge effects that the inverters will clip - at least not around here. One thing to consider is that if you go with smaller modules you need more inverters. You might compare the cost of the additional inverters to the value of the 0.2% energy loss from clipping over the lifetime of the system. Dana Dana Brandt Ecotech Energy Systems, LLC www.ecotechenergy.com d...@ecotechenergy.com 360.510.0433 On Mon, May 10, 2010 at 11:36 AM, Marco Mangelsdorf <ma...@pvthawaii.com> wrote: I just don’t understand why going over 20 percent of module nameplate to nameplate inverter rating makes any sense. I regularly see 120-130 percent of nameplate amperage coming off of the array on our office due to edge of cloud.
