According to the most recent mining report by Wayi, which ranks No.9 both in BTC and BCH mining pool, 325,000 S9i 14T have been deployed in the last fortnight and the hashrate of BTC network is expected to increase.

This report briefly analyzes BTC and BCH mining market from the perspective of price, difficulty, miner sales price, mining revenue. The numbers are based on Antminer S9i (14T/1320w).

Static analysis:

For mining BTC only, the static ROI of one unit of S9i is 256.55 days, in which electricity is accounted for 45.59%. The bubble index for miner and BTC price was 1.73 and 12.66 respectively. The difficulty in the last three months increased by 37.1%;
For mining BCH only, the static ROI is 231.92 days, in which electricity is accounted for 43.10%. The bubble index for miner and BCH price is 1.73 and 83.8 respectively. The difficulty has increased by 37.1% in the last three months.

Dynamic Analysis:

For mining BTC only, the annualized ROI of S9i 14T miner in terms of RMB is 56.56% (without depreciation) and -8.74% (with depreciation). If it’s based on BTC terms, the annual ROI of S9i is 73.45% (without depreciation) and 53.99% (with depreciation).
For mining BCH only, the annual ROI of S9i 14T miner in RMB is 66.47% (without depreciation) and 1.18% (with depreciation) and 86.33% (without depreciation) and 66.87% (with depreciation) in terms of BCH.

The report concludes that mining BCH is slightly more profitable than mining BTC. However the bubble index of BCH is 83.8, far exceeding the safety level of 3. The bubble index of BTC 12.66, which makes BTC the better choice for the majority of people.

In addition, this report reveals some interesting statistics on the BTC and BCH network.
The active address on BTC and BCH is 519,805 and 35,873, which is why the bubble index of BCH is much greater than BTC as the bubble index is calculated in the following formula:

“The bubble index = total market value (billion) divided by “60-day average active address (10,000)^√2”

At current 35.36EH/s hashrate, there are equivalent of 2,525,714 units of S9i validating the BTC transaction, which is an increment of 325,000 units over the last period. Also the power consumption accounts for 0.117686% of the global scale. The power cost is around 0.5 CNY per kwh as it is told by mining farm operators.
Currently, the market price of S9i 14T is about 4,850 CNY (including official PSU), plus 50 CNY of power cables and transportation cost. The deployment cost per TH is equivalent to 350 CNY(4900/14T).
Depreciation is another factor to consider. Wayi considers the manufacturing cost of S9 is around 2,800 CNY and assumes that the second hand S9 could be sold at 2,520 CNY(90% of manufacturing cost). The number leaves plenty of safety margin for potential mining investors. The newly-deployed 325,000 units indicates more machines are being deployed.