no, your calculations are way off or at least misunderstood.

2 panels are in parallel at the array. the long runs (south-facing array)about 60 feet require 1 red PV 10 gauge and I black PV 10 gauge wire. so 120 feet that is for 2 panels. the short runs (west-facing array) are more like 30 feet so 60 feet of PV wire for 2 panels. if I put 24 panels in the big array that is 12 runs = 960 feet. and 16 panels short wire runs are 60 feet per 2 panels so 8 runs = 480 feet of PV wire. so I estimate 960 feet plus 480 feet of PV wire for 20 runs for 40 250-watt panels =1460 feet of 10 gauge PV wire or 730 feet of red PV wire and 730 feet of black PV wire 10 gauge. the wire cost $250 dollar delivered to my doorstep in 1000 feet rolls so I have less than $500 for PV wire. more like $375 dollars for the 1460 feet of PV wire (a bit less even).

Your wire calculation is 2400/375=6.4 is inflated 6.4 times over actual cost. you say 2400 dollars for wire that costs 375 dollars.

the excess solar PV will be used to heat the house directly thru solid-state relays (DSSR20 with diversion).

I liked the radiant floor heating idea and also have a superinsulated multi-story building (a different location) with many south-facing double pane windows to collect the solar sun in the winter designed for in-floor radiant heating. I think I will put the resistive or hydronic in-floor or underfloor heating in that also using the electricity from the sun. I believe solar energy is the way to go. I am trying to go off-grid sustainable in all new construction I do. DIY what you can do!

6 250 watt panels were putting out 1100 to 1200 watts in the sun yesterday on the 60 feet runs(1162.7 watts in the attached photo). the incoming voltage was 36volts from the 3rd set of 2 panels I hooked up yesterday. the 6 south-facing panels were charging the 24-volt battery at 41.898 amps. I had the DC light on in the insulated 8x8 foot power shed as the small load and maybe another light.

The solar panels are mounted at 45 degrees.

I still need to look at the voltage drop issue but the code says not important at less than 75 feet.

I have not calculated voltage drop on the 60 feet runs of 10 gauge PV wire from the solar panels to the DSSR20's; but it does not seem to stop the battery charging one bit.

maybe you can calculate that for me?

one solar panel is only $2340/40 = $58.50 so the delivered price to me was 58 dollars and 40 cents per 250watt solar panel.

the dssr20 cost $877.06 for 20 DSSR20's (4 of the DSSR20's have diversion so I can use for heating) and 1 SBMS0 (wifi version) and 2 DECT16 to control 40 250 watt solar panels (10,000-watt PV array).

the Electrodacus monitors watts and amps in 3 decimal places and balances the 24-volt 16cell 2P8S LiFePo4 battery while charging.

I bought the wifi version so I can view it on a larger screen. (not done with that part yet).

if I would have bought higher wattage 60 or 72 cell solar panels, then I could easily have a larger array(higher wattage). the SBMS0 will control up to 18,000 watts of solar power from the array. this build is 10,000 watts at this moment.

the panels weigh 41 pounds each so not an easy task to mount them. bigger panels weigh more and are more difficult to handle. These panels are 39 inches by 65 inches so 117 inches x 130 inches requires about a 10x12 foot mounting surface per 6 250 watt panels.

I built a 10-foot by 12-foot array mounting structure to fit 6 250 watt panes at a time.

the mppt solar charge controllers cost about 500 dollars each for outback flexmax 80 and will only control a few panels. I believe they would only control 6 of the 327-watt panels if I remember correctly. no savings there.

I needed at least 6 flexmax 80 for the 40 327 watt panels so no bargain there. I bought 4 of those. plus combiner boxes etc for that 48-volt system

the inverter prices are essentially the same whether it is 24 volt or 48 volts. wire to 24-volt inverter or wire to the 48-volt inverter is also essentially the same price.

with LiFePO4 you have to have a BMS. The SBMS0 is the BMS so you have to take that out of your price comparison as you will need some sort of BMS regardless. the SBMS0 cost 159 or less and is a very nice accurate BMS. I regularly check its output readings with my multimeters.