Unquestionably Confused wrote:
| Morris Dovey, wrote the following at or about 6/7/2007 9:20 PM:
|| That shop is 30' x 40' - so floor space will be a bit less than
|| 1200 sq ft. A comfortable daytime temperature is anything in
|| excess of 72F. If there's a run of especially sunny days, the
|| owner will probably need to open windows during the day to keep
|| the temperature in the 70's.
|
| Any idea how impressive that is to us dorks who are paying into the
| grid?g That's incredible, Morris. If you don't mind saying,
| what was the cost of those "Panels of Madison County."
It's not a "Bad Thing" to pay into the grid - it's only bad to pay in
more than is needful. Solar energy isn't a panacea, but in some
applications it does offer solid economic advantage.
I don't mind saying - but I say it at
http://www.iedu.com/DeSoto/sc_prices.html so no one finds an old price
in the archive and gets PO'd because I ask 'em to write a check for
more than what they'd found.
The sun does deliver an impressive amount of energy to our little
planet. I've knocked myself out to produce a design to capture
everything from low-frequency EM through UV, and it seems to pay off
(most notably in the IR range). If you haven't seen the plot of solar
energy distribution by wavelength, you might find
http://www.iedu.com/DeSoto/Absorber.html interesting.
|| I don't remember - I think he told me that it's a 20kBtu heater.
|| Food for thought: in the solar context, his ceiling fan will be
|| even more important than his unit heater.
|
| That's close to what I use in my shop. I think the high output
| mode on the Dayton is 17.5kBTU
|
| I can understand the necessity for the ceiling fan as we have
| cathedral ceilings in the kitchen and family room. Certainly helps
| to balance the heat from the wood stove out there.
In this shop, the insulated 6" concrete slab acts as a big thermal
"flywheel". Since warmed air "wants" to stay up near the ceiling, the
fan is necessary to shoot it down to warm the floor. When the sun sets
and the solar panel shuts down, the heat stored in the floor radiates
as IR to extend the daily comfort period and prevent the shop
temperature from dropping anywhere near the freezing range overnight.
|| Always glad to do that - on the other hand, one of the purposes of
|| that web page is to demonstrate the total absence of magic. On the
|| third hand, there's more to the design than meets the eye. g
|
| It certainly does make a point. No magic, but the output is way
| more than what I ever would have guessed for those two panels in
| that sized structure.
The structure is well-sealed and well-insulated, which is important
regardless of heating system. If you stand a full arm's length away
from these panels at noon on the winter solstice, these totally
passive panels will blow your hair back - if you have hair vbg
It's important to panel efficiency to get the heat out of the panel as
quickly as possible. By designing to maximimize capture bandwidth and
to maximize the volume of air flowing through the panel, the panel
operates at a lower temperature and delivers more heat. Operating the
panel at a lower temperature reduces the black body (IR) radiation
back through the glazing, and lowers conductive losses through the
panel body. It's a balancing act, but as you home in on the balance
point, panel performance does seem to peak spectacularly.
--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/