This is a really interesting discussion, and has provided a lot of additional considerations for my paper-design work -- which makes the puzzle all the more interesting.
Thank you! -Luke On Thu, Jul 30, 2020 at 8:41 PM Haudy Kazemi via EV <ev@lists.evdl.org> wrote: > Willie, thanks for the details. I suggest trying again but this time, in > addition to the true east/west orientation, also put them 90 degrees apart > from each other at their peaks. In other words, each should be at 45 degree > angles to the ground. This will limit total illumination as the sun cannot > shine squarely on two sides at once. It should also flatten the daily power > curve from approximately 10a to 4p (varies by day length). Some solar > energy will still be left uncaptured around noon due inverter clipping on > bright days, but the inverter will run at full capacity longer. Enphase has > a whitepaper discussing DC:AC ratios. > > Thinly overcast days may also produce better than you may first guess. The > high DC/AC ratio can partially compensate for even, but lower intensity > light. PV cells with low shunt resistance do better in low light. > > https://www.pveducation.org/pvcdrom/solar-cell-operation/shunt-resistance > > https://www.pveducation.org/pvcdrom/solar-cell-operation/impact-of-both-series-and-shunt-resistance > > > Bob, I do not believe diode isolation is needed, at least if one is using > exactly 2 parallel strings made up of commercial modules which come with > built-in bypass diodes. If using more than 2 parallel strings, things are > different. Also, designs with >2 parallel strings will definitely need > per-string fusing to prevent current from 2 good strings from overloading > the wires of a failed 3rd string if that 3rd string somehow shorts out the > other 2. > > Last, user bcroe from the solarpaneltalk.com forum website has an > east/west > array: > > https://s93.photobucket.com/user/bcroe/library/ENERGY%2520CONSERVATION/East%2520West%2520Facing%2520Solar%2520Array# > ! > > > On Thu, Jul 30, 2020, 09:26 Robert Bruninga via EV <ev@lists.evdl.org> > wrote: > > > True, south always better. But the point is that then you need an > inverter > > with twice the capacity.. > > The topic being discussed is being able to share an inverter with > > additional panels facing a different direction. > > > > Key points: 1) when not facing due south, panels should be less tilted > > since the sun rises in the NE and sets in the NW, having flatter panels > > gets more sun time in the middle of the day. > > 2) Even if both panels are quite illuminated at the same time, the MPPT > > inverter will not be overloaded. It will always adjust to max power and > no > > more. SO having some overlap is OK. > > 3) In my case, my SE panels begin to be shaded by 2 PM, so I installed > > another set of panels facing SW that begin to be unshaded about the same > > time, > > 4) You must parallel them with diode isolation. > > > > Back to #1, remember that even FLAT panels will produce 80% annual totals > > of the ideal south panels. They are terrible in the winter but make up > for > > it with the double high-sun in the summer. Though do not do it, they > will > > collect dust and cant wash off in the rain. Im just makiong the point > that > > the only placew where you tilt to latitude is due south. Other > directions, > > less tilt is better. > > > > Bob > > > > On Thu, Jul 30, 2020 at 10:00 AM Peter VanDerWal via EV < > ev@lists.evdl.org > > > > > wrote: > > > > > FWIW I did some simulations using PVWatts 2 a while back to see if it > > made > > > sense to have a panel facing east and another facing west, like you > > > describe(tilted to match latitude). I was hoping this would result in > a > > > flatter power output through the day. Turned out that in almost all > > cases > > > it was better off to have both panels facing south(tilted to match > > > latitude). > > > More power across the whole day and obviously more daily energy > produced. > > > > > > July 29, 2020 6:55 PM, "Willie via EV" <ev@lists.evdl.org> wrote: > > > > Yes. With a vertical angle between of 30-40 deg; a pair of panels > make > > a > > > near equilateral triangle > > > > with the ground. I'm wondering if I might see better results by > > reducing > > > that angle between panels. > > > > > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20200730/7264ffed/attachment.html > > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > ARCHIVE: http://www.evdl.org/archive/index.html > INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org > Please discuss EV drag racing at NEDRA ( > http://groups.yahoo.com/group/NEDRA) > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20200731/45149d5e/attachment.html> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/index.html INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
