Have found renewed interest in exploration of UPS (uninterruptable power supply)

After 2 hours (thank you Fidelity team and Rosewawr management for putting up with my dumb questions) I have come to the conclusion that someone could be the Palmer Luckey of energy very shortly. 

Strong return on investment, needed by everyone, and the math of figuring out the profitability is quite easy. 

important:
1. Battery lifetime (10y lithium before 80% efficiency)
2. Cost of installation 
3. Max energy usage
4. Whether you want to sell back to grid (home renewable energy is a scam to en extent in relation to UPS)