Some utilities offer credits to landlords for energy-efficient appliances, HVAC equipment, and many other environmentally friendly upgrades, like low-flow faucets.If you’ve started renovating your property’s apartments, put a hold on it.

most NOO (non owner occ) rentals require 25-30% down, then you will need closing costs, capex/maintenance reserves, plus any costs to upgrade the place and get it listed and carry all the costs till a full time renter is in there (could be tough with COVID).

I would look at the amount of rent you are able to get, deduct property management fees, mortgage interest, taxes, insurance, an estimate for repairs and upgrades over time, and then make sure the number you are left with is still positive. 

After a few years of marriage, we refinanced it to a 15-year mortgage and moved to another house (upgrade).

It's a great opportunity to upgrade a unit and get those rents up to market value!

Is there anything more than a letter or notice telling my tenant of these upgrades, dates, and any disruptions or outage periods with utilities (Electric for a few hours i'm assuming) that I need to do. 

@Vincent FranzeseIf you do not want to pay the monthly fee, just buy the Quickbooks physical software for a one-time cost (you will need to upgrade every few years).

We have been roommates for years and just upgraded to a property that I purchased and now they are paying the rent to me instead of a landlord.

Have extensive resume and projects completed.Am currently finding projects in DFW that others are missing as we understand how to re-design/re-work/extend/upgrade and do the work etc (not flip) to release significant equity. 

If you have good paying tenants in place you can ask them if they prefer unit upgrades for an added cost.