The Renewable Energy site for Do-It-Yourselfers
Collectors Using SRCC Rating Data
The document below is a good example
showing how to use SRCC performance testing data along with prices to evaluate
several collectors to see which one gives the best price for performance for a
specific application. You can easily perform an analysis similar to the
one Alan uses for your solar heating application.
The only caution I would offer on
this excellent example: Because some of the collectors that Alan was considering
have not as yet been rated by the SRCC, he was forced to use performance data
for similar collectors that have been rated. While this is certainly a
reasonable think to do, it does carry some risk, as collectors rating
(particularly for evacuated tubes) do vary over a fairly wide range.
Download Alan's Collector
Comparison Example (pdf 20K)
See also these pages:
Where to get the SRCC ratings data
interpreting SRCC collector test data.
And, here is an email comment
on Alan's chart from Drew Gillett:
Thank you Alan. The data is
interesting and helpful. I have drawn the same conclusion for years but carry
it even further.
After considerable research I have concluded that
the SRCC test presentation method vastly underrates collectors with steep
slopes on their efficiency curves. This is most notable with
www.dawnsolar.com but is true of all
the flat plates. This is because the performance on the partly cloudy and
cloudy days assumes the radiation is equally distributed over the day when in
fact that radiation comes in spurts as the clouds roll by. An unglazed or
low slope collector might not reach the minimum delivery temp under the
average insolation (and so is scored zero production) , but certainly does
produce significant output under the real life variable insolation. This is
compounded by the fact that the test method is limited to small (less than
10x10) collectors and can not account for the advantages of large format site
built systems ( such as dawn's and Steve Baer's and Francis Dewinter's) .
Further the weather data does not take into account that the collector's
losses modify the local environment at the collector . this is most important
for wind and temp effects.
www.solarroofs.com has some inexpensive lightweight collectors that are
SRCC rated. he will be on extreme home makeover soon.
Recent data from Robb Aldrich publicized by CARB
http://www.carb-swa.com/PDF%20files/CNMay07.pdf (please read this) lends
some credence to that. below is my email commenting on their newsletter and
the reference. perhaps you and others would like to provide the SRCC numbers
and costs for dawn and the others above to Al Rush for inclusion in his