@Jessica Jay-Maleskiundefined I learned this the hard way as well, some of my experience. The best way I have found to keep the utility bills down is to make the tenants responsible for paying them, funny how that causes usage to drop significantly.
1. For tenants that have used window AC units I charge a fee, per AC unit, per month. As you said, they use a lot of power, the fee helps to recoup some of the cost.
2. Separating utilities is something I have done in almost all of my units, the last 2 should be done in a month. It all cases for me the cost of separating the utilities has been worth it.
3. I have solar on my own house, and love it, but not on a rental. I don't know your market, but my local market people don't appreciate the value add of solar, so on resale you tend not to get much of your investment back.
Something else to consider, I read about some people who use a RUBBS (resident utility bill back system). It is basically what some people have suggested, most commonly shared breakdown depends on either square feet, or number of people per unit.
Good luck and let us know how you make out.
Russ
