I like the thought of ease of installation for these all-in-one systems. To the best of my knowledge (and I should probably check with my contractor), I do not have to have UL listed equipment.... I'm out in the middle of nowhere in oklahoma.
the inverter is a DEYE 8k which from my understanding is the parent manufacturer of the Sol-Ark 8k?
links to spec sheets below
Deye 8k inverter
200aH powerwall
"Operating temperature range -20 ~ 50[C]"
"Life cycles > 6000"
Don't believe 6000 cycles. A third-party test of dozens of lithium batteries had only a couple that reached 3500 equivalent 100% cycles (ending with about 80% of original capacity.) Sony was one of the those. 95% of the units tested failed, needing replacement or repair. Many showed much more degradation, like to 50%, and many reached or were projected to about 2500 or 1000 cycles.
How much will you draw at night? If 35 kWh or 87% DoD, then you will need 3650 cycles to last a decade. If 10 kWh then only 900 equivalent cycles. Normally for off-grid people thing of 3 days operation without sun. Generator lets you go smaller. Sized for one night would be the minimum. I favor more PV, less battery, but my use is grid-backup.
The temperature range is OK for discharge. Not mentioned here is charge, which can't occur below 0 degrees C. Keep battery warm, and BMS ought to have low-temperature disconnect to prevent charging below that temperature (try to find that in documentation.)
Your 12kW (STC) array will produce about 10 kW, and with 40 kWh of battery that's 0.25C
Discharge is shown as 1.0C max, charge is probably 0.5C max (at nominal temperature.)
Some cell brands show charging 1.0C OK at room temperature, cut in half to 0.5C or 0.7 degrees C
With 0.25C available (half my presumed max charge rate for this battery), I suggest setting low-temperature charge disconnect at 15 degrees C, or at least 7 degrees C; don't let it charge that fast down towards zero degrees C.
...I glazed over...Soooo far past me...... but, does this mean that the claims of the -20F chargeable LiFePO4 cells could be true? Based on what i’ve read in this forum, not for any practical use. I’m no expert on the matter, though.
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Deye vs. SolArk - appears both began as same design, but thought Deye wasn't supposed to sell in US? For a higher price, SolArk may have better support. There is a 12 kW (PV) SolArk, but it's AC output is about 8kW or 9kW max. It supports AC coupling of grid-tie PV inverters that have frequency-watts; moving some PV panels to such an inverter could allow more AC power during peak sun.
I'd be worried the DEYE is a cheap knock-off of a superior product. When I look at the images of the two products they're not identical (e.g., Sol-Arc has on/off button on the front, the display is different, different case, the DEYE weights 99 lbs, the Sol-Arc 75 lbs), so it's definitely more...
diysolarforum.com
What are your loads? Any big induction motors like a well pump or air conditioner? Starting surge is about 5x the nameplate rating, so an 8kW inverter should start up to 1500W load (my small air conditioner for 1000sf house is bigger than that.) If inverter has a surge rating to higher wattage for multiple seconds, use that. It is possible to reduce the surge with a soft-start, or 3-phase inverter drive motors have no surge. There are several top-name low frequency inverters known to run motor loads well. Make sure what you select will meet your needs.
Those "SanTan" white-label panels are cheap, but put out less power per unit area. Big question is whether they degrade faster than others; panels vary greatly in quality/durability. I understand these were originally Trina, who makes good panels today but replaced a bunch under warranty in the hpast. Without UL labels, could be a problem for fire insurance. You can pay more for premium quality and 50% higher output in the same area.
Your 2400 sf "cabin" is 2.5 times the size of my house. But I have a huge PV system (just because I can.)