[Greenbuilding] Solar Hot Water

[Rebecca Weld]

Hi!  I need help sorting out some mixed signals I am getting regarding solar
hot water.  I am an architect trying to advocate for green building methods in
my area, but in this instance I am getting recommendations from a couple of
different contractors that are conflicting, and I thought the people on this
board could help me sort it out with their much greater experience.
One the one hand is the guy installing evacuated tube solar- in this case
Sunda- Seido products.  I'm being told that not only will the water be hot
enough to heat the building in winter with either hydro air or radiant floor
heat, but that we will be able to convert the heat to cold air in summer using
an adsorption process (and another piece of equipment, obviously).
The other contractor doesn't deny these possibilities, but seems to regard
them as new-fangled and untested.  He recommends a flat plate collector- (I
thing AEC brand?).  He is a much more established person in the field- the
first guy has a reputation as relatively flaky)
I'm not sure what to conclude-  the evacuated tube technology definitely seems
to be available, and not entirely wacky- in fact it makes a lot of sense to
me.  But if I recommend it to a client, am I making them a guinea pig?

Thanks in advance!
Rebecca Weld, 
Registered Architect and LEED AP