[Strawbale] Chinese-made evacuated tube collectors and boilers vs. hot water heaters

[Shody Ryon]

I might be wrong. It doesn't make sense that evacuated
tubes would be used for very high temps and be
considered less efficient.
In the book "Solar Water Heating" Page 27 states;
“Since their conception much has been said about the
efficiency of evacuated tube collectors. They are
commonly heralded around the solar industry as a more
efficient collector. If you were just to look at the
collector designs' that is a n easy assumption to
make. Normally, if you reduce heat losses, in this
case by the vacuum of the tubes, you would increase
efficiency. So it may sound counterintuitive if I tell
you that flat plate collectors are actually more
efficient for all residential and most commercial
applications even though they are not as well
insulated.  It takes more than a clever design to
produce hot water. It takes a system that is
appropriately designed to do what you want it to do.
The measure of a collector's efficiency should be how
well they preform when put to use. The best way to
measure that is through an independent testing
organization.”
Paraphrasing:
The Solar Rating and Certification Corporation.
So apparently, this is a good way to compare systems
and units.
Later in the book he goes on to state that flat plate
collectors cost $25 a square foot and evacuated tubes
cost $75 a square foot, so if the Chinese have low
cost ones out now, that might make a difference. He
also speaks to the seals in the evacuated tubes being
guaranteed for 10 to 15 years, if at all, while the
flat plate last a lot longer.
Shody 


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