No doubt that this is a good news for miners, but I'm afraid we need a bigger drop in difficulty for Bitcoin mining to become profitable with the current price of BTC for those paying $0.12 per KWh. But for those paying $0.07 per KWh or less mining is already profitable and this a good news indeed, especially considering that most likely the price of BTC will rise eventually.
Electricity is an important factor, but what people tend to overlook is how high the expenses of the larger farms are when it comes to their employees, the ground and properties they rent, etc.
Even if you're a smaller miner with a relatively higher electricity rate, you can still have it work in your favor with how you don't have much external expenses to focus on, especially if you don't mind mining at a loss.
The larger farms have to cough up the same amount worth of expenses on a monthly basis, and with the price tanking, you have to sell more coins to pay the bills. A 15% lower difficulty adjustment isn't doing much here.
I think electricity is the most important factor, and here's why. For a big mining farm with dozens of thousands of miners all the other expenses, like employees' payment and rent, are negligible. In an article on Bitmain's farm in Inner Mongolia, they say that they need 50 employees to watch over eight buildings filled with 25,000 machines.
$600/month considered a good salary in China so I doubt they pay more to those workers.
$600/month x 50 = $30,000/month (to pay employees)
And I bet they pay not more than $3,000/month for the land those eight buildings are located in the Inner Mongolia.
$30,000/month + $3,000/month = $33,000/
month (employees + rent)
While, as they say in the same article, their
daily electricity bill amounts to $39,000.
Source:
https://qz.com/1055126/photos-china-has-one-of-worlds-largest-bitcoin-mines/