The preceding sentence shall not apply to—(A)nonlodging commercial facilities which are available to persons not using the lodging facilities on the same basis as they are available to persons using the lodging facilities.[1](B)property used by a hotel or motel in connection with the trade or business of furnishing lodging where the predominant portion of the accommodations is used by transients; (C)a certified historic structure to the extent of that portion of the basis which is attributable to qualified rehabilitation expenditures; and (D)any energy property<<<Quote Ends>>>By my reading, 50(b)(2)(D) applies, as solar panels are energy property, I believe. 

A couple of years ago I had a rental and listed on Zillow and Craigslist with somewhat mixed response from each which I attributed to December as being the listing month. 

You should be more clear on your data sources and your data attributes, so we can truly understand what you’re doing here so we can decide if there’s any value here

There are five attributes to any mobile home park deal:1) Infrastructure2) density3) economics4) age of homes5) locationUntil you understand the impact of each of these on mobile home park values and operations, then don't risk your money.You can find the answers to these five topics at Mobile Home University. 

I also attribute a lot of our success to networking.

I do know that CT continues to have attributes that are sought after.

The Act specifically states “ No landlord shall rent or cause to be rented any unit in which the tenant is responsible by agreement, implication, or otherwise for direct payment for utility service to the utility company and in which the utility company billing for that service includes any service to common areas of the building or other units or areas used or occupied by persons other than the individual tenant and those occupying the unit with the tenant on the utility account…” Now of course there are a few exceptions to this rule such as if there is full disclosure to any potential tenant prior to offering an initial lease, etc… If those exceptions are not applicable, but the general rule is, then “Upon proof by the tenant that the tenant was billed an amount for service not attributable to the unit or premises occupied by the tenant, the landlord shall be liable to the tenant for 100% of those utility bills.”

Like many other parts of the country, I attribute this to low-interest rates coupled with more people desiring larger living quarters since they’re going to be living, working and schooling from home.

." ~ Abraham LincolnThis quote is typically attributed to someone representing themselves in court, but it could easily apply to real estate investors.Getting your license to represent yourself in a transaction may save you some commission, but it may also cost you a lot.

If they are claiming 20-30% returns they are probably attributing a large portion of that to capital gains and not rental returns.