I would think area. Why would a business go solar if they pay lower kWH per their zip code or they get govt subsidies for installing a diesel generator / 220v charging station in the parking lot (that no one uses). Your offer has to be lower than those subsidies including the Federal tax credit. If I was paying $. 09-. 10 cents a kWH, why go solar which could be . 17-25 kWH?