Nobody talks about an Antminer S9. First of all, those coins who are not fair like Monero bring the need to switch the miner regularly for the next, more powerful. And secondly, I am talking about a very low power system on a chip, optimised for running a fair coin like Monero.
It's a great idea but at this time don't think it's economically feasible. Panels are pricy, batteries are also. PV (photo voltaic) systems are only working about 6-8 hours out of the day so if one wants to mine for 24 hours a day the system would have to be oversized enough to charge the batteries to carry over for the 16 hours that the PV isn't charging to any degree, just don't think the amount of money one gets from mining will offset the costs, maybe a wind generator to help in a reliably windy area might be an idea to pursue or home sized hydro electric if there's a reliable stream?
The wind and hydro aspects are a great idea. The solar power idea aims a poor countries, where sunshine is plentiful. And I don't think that such a panel would only bring power for eight hours, at least not in summer.