That is too steep. I'm pretty sure that I did a detail study on PV watts and concluded that panels should be at lower angles the further from south that they are. If you put solar panels to the SE and another set in parallel to the Southwest (especially if there are trees in the middle that limit each one to mostly morning and afternoon sun, then I am sure the lower angle does better because it captures more summer sun to make up for what it misses in the winter due to the lower angle.
Further, do not worry about over powering the inverter on the best brightest mid-days since the MPPT controller will still only max at its rated power. Yes, you will be loosing some peak sun on those best days, but the lower angle will give more power on less than 100% perfect days because of the longer production. In fact, many installers back east will install 120% of solar panels on an inverter because that will keep it closer to 100% rating for the majority of days that are only 80% as good as the best clearest days. Since solar panels are cheaper than inverters, this makes sense. Bob On Thu, Jul 30, 2020 at 9:41 PM Haudy Kazemi <kaze0...@umn.edu> 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/20200731/cf5b7fb7/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)
