I paid $.65/watt including shipping (bought from a wholesaler on eBay), $2800 for 2 inverters, installation was $1.10/watt (1 inverter would have worked if I went with SolarEdge w/optimizers). I had to take a break from mining when my Edison bill hit $900 last November for running about 8 TH.
I'm guessing you did the ROI math for the solar factoring in other uses at your home, because otherwise I fail to see how spending thousands of dollars in solar equipment is a good "investment". Don't get me wrong, I think it's really cool, but the finances rarely make sense to me.
I really didn't do the ROI math, I was thinking at least I could sell excess production at $.09/kW if mining didn't work. At current hardware price and ever increasing difficulty, it is kind of impossible to ROI even with free electricity, but everybody still wants to mine, right!