January 6, 20197 yr Hi,The I'm looking for someone to check my logic when it comes to designing my PV array . I'm in Cape Town. I have about 8m by 4.5m space on my north-facing roof for panels (there is a large pool heating mat up there too, taking quite a bit of space, and I'd like to leave room for solar water). My inverter says: Nominal operating voltage 360v Vmax 500v Isc 18A MPPT range 250-450v Looks like this was designed for hybrid/grid-tie with around 10-12 panels. The approach I'm taking: It'll probably be one string. Moderate wattage panels are more cost effective than the high power ones. I need to keep the total Voc below 500V (in fact probably below 450V to leave some wiggle room for a really sunny South African day?) I need to keep the Isc below 18A (not going to be a problem with one string). Within those constraints I presume I might as well design to get as close to the 360v nominal voltage at the "nominal operating conditions (one panel data sheet say: "* Under Nominal Operating Cell Temperature (NOCT), irradiance of 800 W/m2, spectrum AM 1.5, ambient temperature 20°C, wind speed 1 m/s." I won't be able to generate enough I don't think to carry all my load, but might as well get as close as I can? Steve
January 6, 20197 yr I think you are right, but, may be, It would be better a pair of strings, fulling roof completely. Has your inverter one or two MPPT? Any shadow?
January 6, 20197 yr Author 1 hour ago, Javi Martínez said: I think you are right, but, may be, It would be better a pair of strings, fulling roof completely. Has your inverter one or two MPPT? Any shadow? HI, No shadow on my roof. My inverter has one PV input, though I do have two inverters the same. Elbow
January 7, 20197 yr On 2019/01/06 at 3:01 PM, Elbow said: My inverter says: Nominal operating voltage 360v Vmax 500v Isc 18A MPPT range 250-450v Looks like this was designed for hybrid/grid-tie with around 10-12 panels Looking at you figures it looks like your inverter was designed around strings of 10 72 cell panels and a maximum of 2 strings per MPPT - roughly 6000W per inverter does that make sense? What does the datasheet say? With your available roof space you looking at a maximum of eighteen 72 cell panels - maybe only sixteen. With two inverters I would go with a single string of 8 or 9 panels per inverter.
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