The solar system adds no value to my property for rental purposes, and I may even be ripping up the roof & replacing it in the new year.Beyond sending a nasty letter through my attorney via certified mail, demanding the company come pick up their equipment, am I required to take any further action or fulfill any obligations regarding these contracts?

It's a roof over your head, to use for a certain time, for a certain reason.

You can get some estimates from contractors for what they charge for big ticket items like to renovate a bathroom, renovate a kitchen, replace the furnace, replace the roof, etc.All wholesale deals should have free and clear title and you should be able to see the sales agreement before submitting the earnest money deposit.

Doing few roof for single family homes in Houston.

Ours is built with stucco siding, concrete tile roof, tempered windows, self-closing soffit and crawl space vents (they melt when exposed to heat). 

Our biggest climate risks in central Texas are typically wind and hail, so anything of concern regarding the roof could get an applicant declined including trees too close to the roof surface, roof over 10 years old, etc.

@Brett Danehey you are going to need our email addresses and then share it with us.

In my area you have to strip the roof shingles at a minimum . 

I hope you or someone is at least keeping an eye on your properties for break ins, squatters, roof leaks, temperature control, frozen pipes (if in cold climate), if you have a basement and sump pump goes out leading to water damage etc.I just talked to two investors in California that have let their properties sit vacant (no mortgages so paying property taxes and insurance).

Pro tip--make sure your exhaust fan in the bathroom is vented to the atmosphere--meaning out to the outside.....go out the roof or out the side of the unit or secured to an opening in a soffit vent grille off the house.