It's a strategy that has proven effective time and again.Five years is a solid timeframe to account for market fluctuations and ensure profitable sales.

For context, 4 adults and all our tech living here, we were running about $250/mo on average per month for electricity anyway... outside of summer a/c useage. so all in all, its saved me about $2k a year if i had to guesstimate for you (it stays hot here through October usually).i still owe about $23k on mine, have no intentions of selling the house. but if i decide to move out and rent the whole house out, our market would support higher rent in exchange for no electricity bill. i think you just need to decide what YOUR main benefit of having the panels are. for me it was for the house-hack, and consistent billing, despite the usage. if its strictly for property value increase, i'm not sure it would be worth it, pending your specific market. 

You should call a couple local banks to discuss the types of investments you may be looking for.Alternatively, a great strategy for someone just starting out is House Hacking.

Many buyers/investors are using this strategy to invest in real estate

It is my understanding that the company works out the tenant billing rates based on your master utility bill to keep it consistent and fair.So, the technology exists BUT is it legal in Maine to bill the tenants in this way?

The appraised value seems low and I am trying to understand the best strategy to challenge this value and the cost / benefit of going through the condemnation process. 

It’s a simple strategy that can pay off big in the long run.

What markets/strategies have you been considering?

It’s great to see your post, sounds like you’re deeply involved in the real estate investing world with a range of strategies.

Even if not immediately then your son would owe it when he sells, so no advantage to this strategy.