Then offer him a deal for $1500yr to keep it green instead a tractor storage facility.

It's a 4 bed 1 bath and I'm open to either renting it or selling it (if I'm offered a price around the ARV).

They are probably including the roof in the price of the solar panels, and they make it enticing by offering installment plans.

Today I was approached by someone who is offering me around $1800-1900/month to rent the property from me to run a short term / medium term rental out of it, primarily for traveling nurses or other business people.

NICE GUY" and if necessary, you can and will take different routes. maybe offer $50 gift card for the inconvenience and keep things in good term but you should stay firm and sound more entitled. 

They also offer a "Mobile Home University Boot Camp" that will provide you a wealth of information. 

Title companies often have a business development person that goes after real estate investors, offering foreclosure lists as an incentive.

I found a property, contacted an  agent, made an offer.

They offer leads ( for sale) through direct mail which I will try next and see how things go. 

It's been under contract a couple times and offers withdrawn.