As a kid, I had a little handheld, battery-powered antenna TV with a 2" screen.

Capacity, solar panels brand and type, battery back-up if so, etc? 

I buy good, used reconditioned appliances from the Habitat for Humanity and they've never sold me a lemon. 

Ensure all smoke detectors are accounted for and have a working battery.

It's battery operated and you program a code. 

If you filled up with gas once this year, saving you $5,000 in gas (that's a LOT of miles you do to save that much in gas), you must spend a lot of time sitting by the side of the road with an extension lead waiting for the batteries to charge.

Even though I had a battery swap plan, I would get the inevitable call about a chirping alarm.  

Wireless and battery-free.

If the power goes out, you need a battery back up on your sump pump. 

For example, you can't give a holiday gift to only who you think are good tenants because one of them would post "Thanks Sam for the $25 AMC movies GC my boy friend and I saw Avengers last night xoxo" then your other tenants who didn't get a GC will feel left out.I visit my properties once a month for regular maintenance, mostly for little stuff, like changing AC filters, test smoke alarm batteries, test GFCI receptacles, pour bleach down AC condensate drain lines, exercise water supply stop valves, feel under any drains to check leakage, test water heater T&P valves, etc etc etc...they do not need to be done monthly but that's what I do at each property.