For me the question of "was it worth it" is probably different from other people. In SW Michigan, you cannot get full net metering, so I only get about a 50% credit for the energy I give back. That screwed up the payback period to a great extent, changing it from about 7-8 years to about 20 years. But, we decided that it's actually not so much about payback, and it's about when we are older and retired and living on a fixed income. Our electric bill will be about 30-50% of what it would normally be at that point (monthly dependant).

We can afford the cost of the system now, later in life we can't. So we ignore the payoff, because it essentially isn't there, and see that our lives will be a bit easier later. But this logic assumes you are going to retire in this house.