Final solution

So I flew 15000 kilometers for my vacation, just to spend it sick in bed. This has led to several days of cruising pv porn and now I have a lust for 4000 more beautiful watts. Since I have the [new to me] Flex power2, and 2 now extra FM80s I want to do my final additions to the house/shop system before I get too old to lust for anything.

I am looking at bulk panels [off commercial I reckon] by Santan Solar. I do not understand why there seem to be Lots of used commercial panels on Ebay etc at the moment.  Perhaps someone in the commercial trade could enlighten us. Anyway, as I am less than a day from that warehouse, I can test and pick up. The ones of interest are Sunpower 250 blk Mono, claiming high efficiency. These were made with micro inverters, which it seems Sunpower pulled and dumped the panels. I have a query in to Santan re this. No sun power warranty. One year vendor.

Spec 250 watt

VOC 48.8 v

VMP 40.5

ISC 6.56

Max power 6.17A 

Tolerance -3%+5%

72 cell

Our lowest low -10f very rare, +10 fairly common. Altitude 7500, latitude, 32/long 104

So, at current price I want 20 of these. BuT…..

My best non ground mount, non shade location is atop my 29 foot long quonset style shop building. This would be an east/west install in portrait of 2 rows max 10 panels each at 32 inches x 62 inches each. So whats best? 3 strings of 3, per array, [ got 2 FM80s] or 5 strings of 2, for 2500 watts nameplate. Then derate 15% for east west, or more, 3% wire loss, 2% just because and I am giving the FM80 2000 watts per string at whichever voltage. Combiner boxes, racking and wire costs are important  but so is quality. We are building on what I saved as a wage slave.

I want all you to opine here, given my respect, and I have never been shy about asking, but I have one more request. I would like to enter a remote fee based consultancy of some sort with a practical and skilled off grid designer. As I see it, I would send a document of my cobbled together stuff, [most from NAWS] pics diagrams explanations etc. And the designer would advise on corrections, directions etc. Because my whole remote place happened a few months per year over 12 years, due to out of state work, no permits have ever been requested. And I have a very short memory for names. PM me.