At the current Bitcoin price level it is very hard to make a profit even with zero cost electricity. How is that possible? Depreciation of mining equipment.
But I read somewhere that it costs ~40 USD per bitcoin for large miners due to mass production and hence lower maintenance cost per unit. I dont think none of the large bitcoin firms would have run unless they made profit. Both Cex.io & KNC cloud are closed for customers, but they are mining on their own. Is not it obvious that they are mining because they are making profit ?
It's hard to tell on cost's as most don't share this information. It is somethig that a company really does not have any advantage to release information if they are mining thierself.
And yes some of the big hardware companies, and some big data centers are making money. There is no doubt as they continue to mine, even at this lower level of price. Home miners still can pull a profit to, but you have to mine smart. You might be underclocking more, and doing lots of math.
And as far as thread mining with solar just does not add up. There is so much up front costs, a company is better off getting cheap electricity then installing ton's of solar equipment. It's just a cost vs amount of time to get a ROI on solar.