I just paid 12.5 for a heat pump system, I'm getting a $3,500 or so rebate and I think there's tax implications too. I was told not to use the heat pump when it gets below 30 so we programmed it so the oil would kick on below that. Just looking into solar now, I was hoping the system would be big enough to make the heat pump more feasible when it's colder but I'm not sure how they size solar systems.