Ability to repay - can you as the borrower afford the payments based on the loan amount.Typically they will not take into consideration the mortgage on a new property that has not been taken out as that is new.

With your primary residence, things can be pretty straight forward in terms of splitting mortgage interest, real estate taxes etc. on your returns.If you go into a rental property, there are a lot of considerations to think about.

Once you find a good property and all the numbers make sense - pull the trigger.

So brainstorm the different options then pull the trigger!

They’ve likely invested a considerable amount of time and money into it.

Government assistance/tax credits are of course a consideration that is factored in to the cost/benefit analysis of any form of new energy generation, as all forms of energy are heavily subsidized and always have been, long before solar entered the equation. 

If you have considerable equity in the property or multiple properties it's even more important.

Other KPIs and considerations you should evaluate when talking to any lender who offered private placement of loans/notes are historic default rate, how quickly they can place your funds (do you get preference over their income funds, for example), average interest rate - borrower note rate and what is passed through to you, are loans serviced by a 3rd party servicer or in house.

Also I understand the funds aren't available for the improvements so that is another obstacle that has me leaning towards price reductions to move on as soon as possible.The exit of lower tier SFH's is something very few investors care to consider when making their investments but deserves far more consideration. 

This seems unlikely in the long run. you are forgetting that someone is paying down your principal for you so you need to take that into consideration.