[RE-wrenches] FW: Enphase performance
Marco, I have a revenue grade kWh meter on my 3 Enphase 175 system that is owned by the utility (production based incentive in WA state) and the Enphase monitoring reads about 6% over the revenue meter. This has been over a one year period. I've been very pleased with the performance using either measurement. Brad AEE Solar ___ 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] FW: Enphase performance
Marco, My email doesn't seem to work on wrenches, so I am replying to you directly. 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 Randy Sadewic Positive Energy 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: Friday, May 07, 2010 12:11 AM To: 'RE-wrenches' Cc: 'Douglas Bath' Subject: [RE-wrenches] FW: Enphase performance Marco, I have a revenue grade kWh meter on my 3 Enphase 175 system that is owned by the utility (production based incentive in WA state) and the Enphase monitoring reads about 6% over the revenue meter. This has been over a one year period. I've been very pleased with the performance using either measurement. Brad AEE Solar ___ 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] FW: Enphase performance
Makes you wonder what is officially calibrated to whatis digital more accurate or analog utility meters...?? From: Marco Mangelsdorf To: RE-wrenches Cc: Douglas Bath Sent: Thu, May 6, 2010 8:11:16 PM Subject: [RE-wrenches] FW: Enphase performance Marco, I have a revenue grade kWh meter on my 3 Enphase 175 system that is owned by the utility (production based incentive in WA state) and the Enphase monitoring reads about 6% over the revenue meter. This has been over a one year period. I've been very pleased with the performance using either measurement. Brad AEE Solar ___ 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] FW: Enphase performance
All meters are analog at the point of measurement, because the signals that are being measured are analog. What makes a meter "digital" is the conversion of the original analog data to digital format and downstream data manipulation. Therefore I doubt digital meters are fundamentally more or less accurate than analog. There is one point I would like to make: we have not used the GE I70S, the electromechanical (100% analog) meter with pointers, for several years now. We were told by a Southern California Edison engineer that they were not reliable (i.e. stopped working) and they were less accurate than +/-5%. Sure enough within a month the meter in question stopped worked and required a "rap" on the bezel to start working again, only to freeze up again in a few days. I remember two others that stopped working (one perhaps never worked). We got these puppies from Austin International in SC. We use the Itron Centron C1S and have been happy ever since. - Peter Peter T. Parrish, Ph.D., President California Solar Engineering, Inc. 820 Cynthia Ave., Los Angeles, CA 90065 CA Lic. 854779, NABCEP Cert. 031806-26 peter.parr...@calsolareng.com Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885 _ From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Keith Cronin Sent: Friday, May 07, 2010 12:28 AM To: RE-wrenches Subject: Re: [RE-wrenches] FW: Enphase performance Makes you wonder what is officially calibrated to whatis digital more accurate or analog utility meters...?? _ From: Marco Mangelsdorf To: RE-wrenches Cc: Douglas Bath Sent: Thu, May 6, 2010 8:11:16 PM Subject: [RE-wrenches] FW: Enphase performance Marco, I have a revenue grade kWh meter on my 3 Enphase 175 system that is owned by the utility (production based incentive in WA state) and the Enphase monitoring reads about 6% over the revenue meter. This has been over a one year period. I've been very pleased with the performance using either measurement. Brad AEE Solar ___ 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] FW: Enphase performance
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
Re: [RE-wrenches] FW: Enphase performance
I've got my SMA SB5 on a revenue grade meter and it's actually under-reported slightly since I started comparing it last August. SMA's counter has increased by 5649 kWh while the revenue meter has increased 5666 kWh- only 0.3% off. If I remember correctly from their training session they said they're usually within 1%, but their tech documents say +/- 5%. YMMV. Original Message -------- Subject: Re: [RE-wrenches] FW: Enphase performance From: Kirpal Khalsa To: RE-wrenches Date: 2010/5/7 12:38 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 <http://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
