I had my site survey completed earlier this week, and was presented today with a proposal for an 8.24kW system, with a gross price of $18K, minus upfront incentives/rebates of $9K (I am in IL), minus the fed tax credit of $5K (which I will take), thus yielding a net system cost of $4K (all figures are rounded). Will offset 62% of energy usage. Is this a no-brainer at this price?