I did an analysis for a small 250kw unit, price of generator at $70,000 CAD ($50,000 USD) with an average price of gas at roughly $2750 CAD/Month ($2000 USD) with that generators gas consumption, 85% up time, and thats at 65% of the 5-year average nataural gas price.
That's backyard scale, 250kw install won't make shit or worth your time. You can only really run them at 80% load so that 200kw usable.
Want it to be a hobby go for it. It's not a business model, sorry
Who is going to do the dailies on the gen, oil and filter changes? Who is going to change out the sleeves, pistons and bearings? It takes a lot of money to keep those running.
having just ended a 210-230kwatt mine it is too small unless it is a one man show.
If you are running 60 x 190th t21s you have 11400th or about 570 a day.
So lets pretend your access to the gas is “free”
But you need a box. 35-40k
you need shelter for the generator and box 25k
as you said 70k for the transformer
and 60 miners are about 215k
add that up 350k if you make 570 a day it is just under 2 years to break even.
that assumes 100% up time and nothing breaks for two years.
it also assumes earnings stay at 5cents a th.
having worked on mines for years I can tell you I would not want the extra work of keeping the genney running..
this may be good enoguh to protect the mining box and the generator
https://www.ebay.com/itm/115274046645?