The bitcoin mining calculators are your friend, I dont know what kind of wattage your solar panels are making but i think even at 13 cents a kw your still going to have quite high mining costs.
According to this you will be earning 1 btc every 3 months but you need to take into account that we have a halving in less than a month. Id be inclined just to spend your money on btc rather than mining gear.
http://www.coinwarz.com/calculators/bitcoin-mining-calculatorObviously you need to take into account also the price of the s7. I also probably wouldnt bother with gpu mining unless your wanting to get a good gpu anyway since the only coin im aware of that was worth mining was ether and thats possibly coming to an end.
