"Free" 15KW of electricity is about 30K USD if you DIY (not sure about the price in Croatia, just plug in the right amount
. Then you need to factor in the sun expo, weather conditions and loss of panel efficiency over the avg lifespan of an installation (15/20 yrs?).
Say you're super lucky and everything is maxed out in your favor, the thing will cost you 125 USD per month (30K USD divided by (20 years x 12 Months x 100% efficiency)) and will let you power about ... 10PCs (4x 797OC + CPU etc is about 1300-1400W at the wall with 80+ Platinum PSU with 95% efficiency). Properly configured, you're looking at about 28GH/s. Cool.
Each computer will cost about 2 or 3K USD (quality components). Don't forget about the environment you're running the PC's in to max their lifespan (heat, humidity, power stability, etc), what about batteries, UPS, internet bandwidth, etc which will add to your costs.
Now, start playing with the numbers and see how low you can get before it becomes unprofitable and you'll know whether it makes sense to invest in this venture and how much your % should be to cover your costs (CAPEX/OPEX etc). It's a job
Good luck.
