Posted by v8z on February 16, 2012, 3:58 pm
As mentioned elsewhere in this thread, solar thermal is one of most cost
effective means of using the sun. Rather that using inefficient PV to power
a heater, using collectors that directly heat the fluid, whether its water
if you live in a mild climate, or anti-freeze run through a heat exchanger
to heat water. A small PV 30-40watts can run an effeicient circulation
pump, and there are numerous designs for differential controllers out on the
web, of available pre-manufactured like the Eagle products, to control when
the pumps runs relative to temps in the system.
Posted by j on February 16, 2012, 6:23 pm
On 2/16/2012 10:06 AM, Jim Wilkins wrote:
I've got 6 unglazed panels I made a few years back. Each panel has a 1"
manifold on top and bottom, feeding 1/2" copper risers. The collector
plate is aluminum flashing and is effectively 3 layers. A huge number of
rivets and time involved in bending the plates to form around the riser.
Each panel is 2' x 10' or so (120 SF total). I ran put out of time and
money before I glazed them! And I made the boxes out of MDF which is a
If I were to do this again, I'd probably save all the cost of copper and
aluminum and do a Thomason style trickle down collector with mylar and
SunTuf. Or perhaps a batch heater like yours and save a lot of money and
time! Not to mention having it up and running!
On my south facing wall, I have 200 SF of Kreamer style pass through air
collector feeding into the existing ventilation ducts.
Yeah, I think you either need to be off grid or grid tied to make sense
of PV. But electricity is getting pricier and PV cheaper.
Posted by Jim Wilkins on February 16, 2012, 7:05 pm
The self-contained batch heater requires yard space with good sun exposure
and perhaps more attention to its appearance. I painted mine to match the
foundation and house. It looks like a doghouse when it's closed, not a
wierdo science experiment (got those too). Recovery time for the 40 gallon
tank is a day or two, so it's better for laundry than showers.
Posted by Winston on February 16, 2012, 8:46 pm
Jim Wilkins wrote:
That is high tech, Jim!
Right now, I'm experimenting with solar reflectors.
I have some surplus acrylic mirror material taped to some MDF
which is propped up on a step ladder. It reflects solar
energy from the back yard into the kitchen/living room area.
It brightens the place up a lot. The stuff is $ to $0 a
square foot, so I buy cheap 'drops' of it when I'm in the
area of my plastic monger.
Curiously, aluminum foil did not reflect nearly as well as I'd
hoped. The crinkly surface puts too much power at inconvenient
angles. Also, I find that plain (non-mirror) acrylic appears
to work nearly as well as does the expensive 'mirror' stuff
in reflecting sunlight.
I've also discovered that merely opening a screen door and
allowing my garage exhaust fan to pull in heated air from outside
heats the place up a *lot* faster than does my solar reflector.
Posted by j on February 16, 2012, 9:25 pm
On 2/16/2012 3:46 PM, Winston wrote:
FWIW, I ran across this, again, today:
Since you have the mirror source. Although you can get metalized mylar
I had thought of doing an acoustic stirling (or a simple variation), but
the amount of dead clear days is too few here, and the complexity, too much.
There is a lot to be said for simple ideas that work! Like your
reflector and fan!