2015
In your opinion, are thermal solar water heater systems, especially the ones that require glycol due to freezing conditions also going to be added to this list?
There are special exchange type water heaters that are needed for thermal water heat systems.  PV power can be transported longer distance with less loss and can use a standard resistive element water heater.   The problem with using PV is the thermostats (the contacts) will burn out fast if fed DC.   Requiring a special DC->AC controller.
My opinion about glycol: even special-alloy double-wall heat exchangers can fail, and glycol enter household water.

Glycol might not be attractive investment for homeowner, but all development and promotion today is based on big companies.

My concern about large business is division of wealth and those living 'off grid' considered criminal... but history never follows a straight line.