So I am trying to figure this out. You don't need to run 1000w per 4x4... seems a bit overkill for todays lm301b diode technology. You need about 30w per sq.f. For a 4x4 that is 16sqf x 30watt = 480w. Lets just assume 600 watt per light for CO2 controlled environment or 37.5w per sq.f.
You can pick up a 670w Trina Solar panel for around $0.33 per watt on alibaba:
https://www.alibaba.com/trade/search?fsb=y&IndexArea=product_en&CatId=&tab=all&SearchText=Trina+670w+solar&selectedTab=product_en
Let's assume we want to grow out 4 4x8's which use 8 lights (600w each) for a total of 4800w/4.8kw. If there is one panel for each light there would be 8 panels total which together would produce (theoretically) 5.36kw. You can pickup a 5.6kw hybrid solar inverter for around $350 on alibaba. Add batteries for around $2500 per 10kw.
The cost without batteries would be around $1800 and with inverter around $2500 total.
For a gram/watt that would produce about 11lbs of weed up to 6 times a year, or 5 to be more realistic. That's 55lbs a year. For the examples sake say that's $500 per lbs that's $27,500 a year.
In 2022 the average cost per kwh in the US was 14.5 cents per kwh. If you were to run 4.8kwh at 12 hours per day 365 days a year that would equal a total of 21024kwh @ 14.5 cents would be around $3048.48 per year on average.
Depending on where you live you can also get a government funded subsidy to install solar so that would also reduce the cost significantly. In california up to 30%:
https://www.sunrun.com/solar-by-state/ca/california-solar-incentives
Please feel free to alter the formula. There is no doubt a sweet-spot for optimal production vs cost using solar and it should definitely be something any serious grower should think about when designing a new grow op. Let's get this dialed in for real... I see some of you guys even work in this industry so it shouldn't be that difficult to calculate...