They are expected to do sales, customer service, management, accounting, marketing, people management, etc. and be paid what you would pay, in any other business, for just one of those positions.

I'm putting solar panels on a new 4 plex build so I can pay all utilities under a single payment and make life easier for everybody as it is a medium term to short term rental.

As mentioned, a lender is not going to put money in an account.

It will decrease your cash flow as your single payment will be higher than the multiple payments combined. 

Rather than wasting it or leaving it in a bank account I'm interested in starting my own investment business to supplement my real estate sales.

If a Cost Segregation Study had not been performed on this $595,685 single family home located in Miami, FL, it would have had first year depreciation of approximately $22,000.

Underwrite allowances for - Vacancy, Prop Taxes, Insurance, Utilities, Repairs & Maintenance, a Reserve Account, and Property Management. 

I have 3 single family homes in LTR leases in the Grand Rapids area.

Single family or multi-family?

DIY will be the "cheapest" - you can set up an account on the MA DOR website, register your LLC, you pay over the whopping $500 MA charges you to register an LLC, and voila, you are off to the races.