I doubt the numbers will make sense for that either, but certainly a much more intriguing concept then panels on a roof.

I have not tried them but there are also acoustical panels you can get to help as well.While none of this is required of you, if the tenant otherwise is a good tenant it might be a nice gesture.

I've had them actually fix things even with that contract in place, but it was a huge surprise (new oven and cabinet repaired magically at walk-thru one time, found out bank had already ordered it before our offer, so they went ahead with it), but that is not a normal occurrence.We bought a home with significant cat urine damage, had to take out subfloors, paneling, drywall, etc.

Also, if your breaker panels are at all sketchy (Federal Pacific Electric, or maybe Pushmatic), you might think about swapping them out before adding the load of new heaters.As to how many heaters you need... you can go by the square footage they list, but also think about how people are going to use the apartments. 

I bought a duplex and replaced electrical panels and turned attic space into additional bedrooms.  

The top should be well-supported wood panel design, possibly with the same composite-tile surface that our roof has...So, I searched on Yelp for general contractors who had good user ratings; the first two wouldn't even discuss such a small job; the third asked me 'do you have drawings?'

Here are some that I'm aware of:- Galvanized pipes - typically 40-50 useful life, could rust from the inside out, could get eventual pipe failure- Zinsco or Fed Pacific electric panels w/ aluminum wiring that could be a major fire hazard- Wiring in general (e.g. knob and tube)- Asbestos in the walls- Lead paint- Heating system - boiler?

we bought a home, unoccupied for a long time 6 -8 months and no heat on. during my inspection i pulled a piece of paneling off the wall and exposed the wallboard behind the paneling and found mold. we were able to pitch a lower price and still closed with the bank. once we owned it . we removed the paneling, sprayed concentrated well clorine on the effected walls using a paint sprayer and left the home for several weeks closed up. then started to air the place out. we then used a primer called jammer ( what they use after a fire ) to seal up the walls and proceded to paint the basement and kept the dehumiftifier on after that. so far 4 years have passed and no signs of reoccourance.

The old textured walls and wood paneling are gone.  

@Jing Wei, even if your desire to sell bulk Solar Panels to Australia succeeds, it won't help the WORLD at all - unless you can get CHINA to try the same!...