Your calculations seem to be correct.
I am running about 200kW DC Solar and we are mining with about 20kW Hardware, growing to about 50kW until 12-2018.
So far i cant tell you the solar coverage ... maybe in september all counters are installed and when the logging works for some month i will make a prognosis.
At the moment i try to calculate the costs of investing in Batteries to use as much solar energy as possible.
We are somewhere between 200 and 300$/kWh storage costs i think...
But on the long go its very interesting and the ROI should be <5 years, if solar is available and "for free"...
...
You're MINING HARDWARE:
1x Bitmain Antminer S9 (link) 1,340 Watts
1x Bitmain Antminer R4 (link) 845 Watts
2x Bitmain Antminer L3+ (link) 800W x 2 = 1600 Watts
1x Bitmain Antminer A3 (link) 1,275 watts
2x Radeon RX Vega 56 (link) 210 x 2 = 420 Watts (500W counting the System they're running off on.
Just the Mining hardware = 5,560 Watts x 24 hours a day = 133,440 KWh's Per day and I'm sure I left out many things like the power draw from the power supplies needed to power the Antminers or any additional fans and cooling.
My estimate is that your solar panels are suppling only 27.32% of your homes total energy usage.
Also, you mentioned you're already at $40K in cost and saving $1,995.34 a year (btw: 11.1cents per kWh) That's over a 20 year break not counting tying your money up with no interest and inflation eating the value. Those 2 power walls are going to need $7K worth of new batteries every 10-12 years. Your solar cells will likely hold over 90% power after 30 years.
Sorry to sound negative.
It would be awesome if you would post your actual electric bills.