I would like to find a design that is eco friendly with solar panels, a rain water filtration system, built with sustainable materials and hurricane proof!

Renters are not choosy about what type of windows or if it has paneling, etc.

Your welcome to bring your best Golden microphone to the Jan. 13, 2015 For Investors By Investors meet up (a great established no sales pitch network meeting that I have NO membership/affiliation in) in Manhattan Beach, CA where the attorney will be on a question and answer panel.

Nothing will look great short of an entire panel.  

If so, what did it say about upgrading the panel?

Failing that, if each unit has it's own electrical panel, then you can sub-meter one, or both, of the panels.If the units have co-mingled electrical and share a common panel - or worse, circuits - there is no satisfactory way to bill back the electrical consumption.  

Properly sized breaker panel or fuse panel (yes, fuses are still OK).Plumbing: Are supply pipes non-galvanized (copper, plastic, poly)? 

Problems that affect the "livability, soundness, or structural integrity" are what to look out for, also potential health and safety issues.So for livability:operational heating systems, operational plumbing fixtures with no major leaks, operational electric systems reasonably up to date (No Federal Pacific or Zinsco panel box, no aluminum wiring, etc)Roof with no active leaks - usually with at least 5 years of estimated remaining lifeFor soundness/structural integrity:No foundation issues - cracks, slanting floors, entire house leaning over, etcNo evidence of termite infestationHealth/Safety:No moldPeeling paint, especially in buildings built prior to 1978There's probably more, but that's all I can think of offhand.

How to wire an earthing system if you're installing a single phase panel board. 

I have attended property inspections of STR's for sale that fail electrical due to overfused electrical panels, etc.Our onboarding manager has just completed and is certified through Breezeway safety course :)