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However, regardless of your result, you still need to include the additional cost of your off-grid solar system to ROI since the end goal is to build an off-grid farm.
Or is everything already paid just like the additional 40kW panels you have now?
Yes, mostly paid other than more inverters and mounts for the panels.However, regardless of your result, you still need to include the additional cost of your off-grid solar system to ROI since the end goal is to build an off-grid farm.
Or is everything already paid just like the additional 40kW panels you have now?
How about taking a chance in the $160k bitcoin lottery and solo mine it?
Time estimate: 10 years
0.00000194% chance per block isn't too bad.Time estimate: 10 years
Time estimate isn't really a good basis since this "10 years" could be the block in the next 10 minutes or the next 10 years.
An extreme example is the miner of block 853742 who only had 3.1TH, reference: /index.php?topic=5237323.msg64356985#msg64356985
But don't take that as an encouragement to solo, just saying that a very low chance has a chance.
Annual ROI: Negative until after the payback period (~3.89 years)
At last, someone who doesn't think that "ROI" is the same as "Capital Return". 
Also, take the gradual increase of total network hash rate in consideration and the next "halving" if it would take more than 4 years from now to ROI.
Yes Sir, and how about the projected increase in price,
I recalculated with a 3 X increase in 3 years using todays price, I'll spare all the math.
Future Price = $61,000 × 3 = $183,000
Total Value of Mined Bitcoin After 3 Years
Total Value = Total BTC Mined × Future Price
Total Value = 0.200385 BTC × $183,000/BTC ≈ $36,670.46
ROI
Net Profit
Net Profit = Total Value - Initial Investment
Net Profit = $36,670.46 - $3,000 = $33,670.46
ROI Percentage
ROI (%) = (Net Profit ÷ Initial Investment) × 100%
ROI = ($33,670.46 ÷ $3,000) × 100% ≈ 1,122%