I am curious why you care? Is it close to maxing out cold weather Voc for one more panel in the string? If so I would be conservative and use one less panel.
I have an old Sanyo Bi Array and it pretty much has never gone outside the cold weather Voc that is logged by the controller. The 600v mppt just cranks out the power when the snow is off the array. It does pretty well also when the snow is on it. Just curious what you are doing? Testing used panels to make sure they are good? If so I would line them all up exactly the same and have a second set of eyes to record it all. Dave Angelini Offgrid Solar "we go where powerlines don't" http://members.sti.net/offgridsolar/ e-mail [email protected] text 209 813 0060 On Mon, 2 Nov 2020 10:18:29 -0500, Jason Kechijian <[email protected]> wrote: > Hey wrenches, > > Does anyone have any guidance to which values to use when testing open > circuit voltage on bi-facial modules, considering you take the temperature > reading from the cell vs. the back sheet? Also, what would be the correct > module Voc to use since there are values for both the front and back? > > 405W Module: Front/Back > Pmpp: 405 / 285 > Vmpp: 40.89 / 41.10 > Impp: 9.91 / 6.94 > Voc: 48.42 / 46.99 > Isc: 10.38 / 7.28 > Module efficiency: 19.7% / 13.9% > Temp coefficient Pmpp: -0.3528%/ºC > Temp coefficient Isc: +0.0400%/ºC > Temp coefficient Voc: -0.2769%/ºC > Nominal: 44+/-2ºC > > I was using the front Voc and Voc temp coefficient, but I am getting some > results which are not in line with the 5% of expected. > > Jason D. Kechijian, LEED AP > NABCEP Certified PV Installation Professional™ > > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/[email protected]/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org _______________________________________________ List sponsored by Redwood Alliance List Address: [email protected] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org There are two list archives for searching. When one doesn't work, try the other: https://www.mail-archive.com/[email protected]/ http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out or update participant bios: http://www.members.re-wrenches.org
