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 <[email protected]> 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 <[email protected] > > > 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" <[email protected]> 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)
