Solar Window Heater...

[T-bones]

I have good Sun on one window for about 4 and a half hours a day so I thought I'd try making an in-house-window-heater. I had a large piece of 1/2" ridgid foam insulation. I made it 4" deep and it fit's right over the window on the inside.
It has a port about a third the way up and another one about two thirds the way up with hood over the ports on the sunny side to vent heat into the room as it rises.
Below the vents on the sunny side I installed some verticle fins made from aluminum coil stock to absorb and distribute heat in an instant. I painted the sunny side flat black.
At the top and in the center I installed a 12-volt fan that I snagged from a computer tower that was on the curb. I had some broken PV cells left over from another project so I made a panel to power the fan. I made an adjustable bracket for the PV panel out of the aluminum tubing from an old lawn chair. I installed it on the roof and angled it so the fan starts shortly after the sun begins to heat-up the window unit.
When the window unit is in full sun I get a steady stream of 90 plus degree heat. Also, the heat coming in from the lower ports is dispersed by the fan as it rises.
There has been a lot of debate on wether there is any real benefit from a window-heater vs just letting the sun shine in and naturally heat the room. My experience is this: The window unit is designed to absorb and disperse heat. A white bedspread or hardwood floor or any other surface that might catch some fleeting sun in the winter won't compare to a unit designed for that specific purpose.
I couldn't be happier with it and it also gives that window a better R-Value when the sun isn't shining.

Sorry no pictures

[russ]

Hi T-bones - Welcome to Solar Panel Talk!

Nice project! I don't see how there can be any doubt whether a solar air heater is better than a window alone. A properly built collector will be far more efficient.

Plus, like you said, you have a better R value for the window the othe 20 hours a day.

Russ

[T-bones]

My first post

Thanks Russ. Thought that story was a good way to get started here. I have a lot of stuff to share. I need a camera to post some pic's. Eventually I'll get to it.

Solar Heating units do work great and they save you money and help the environment. I been using several for almost 10 years. If it stays above 35 at night and is sunny during the day I don't need to turn on the heat.

[russ]

I prefer the solar thermal panel to be on the roof, wall or otherwise not obstructing the view.

Here we sit on a hillside overlooking the bay. No way I want to lose that view.

No problem - the panels can be located most anywhere that gets good sun and is connected to the home.

Russ

[ericaminto]

very interesting project i must say. Once thing is you can also use and electric cable if no sun light.

[rollandelliott]

cool idea

I was thinking of making a SodaCan passive heater and putting it OUTSIDE And below the windows with a duct going inside.
The advantage being that the windows would not be blocked the disadvantage being:
1. unit would have very cold air coming into it and the vent would have to be closed at night or a draft might negate any heat build up during the day.
2. It would look kind of funny.

What do you think the most effcient heat sink design is? Soda cans are obviously round pipes, with the back side never getting any heat. but would it make more sense to just have a strip of aluminum 8 feet long 2 inches tall? It would create a surface area much greater than the cans when the sun was perpendicular to it, but as the sun angled more and more of the metal would be shaded.
What would be the most effcient depth? and spacing between the fins? I guess I'll have to go outside and play with it. .

[russ]

Hi Rolland,

Look at

http://www.builditsolar.com/Projects/SpaceHeating/mssungrabber.htm

http://www.solar-components.com/SOLARKAL.HTM#doityourself

There is another one that is better that I haven't found yet.

BTW - your insolation is about double what we get here in the winter - very good.

Year around average is about the same between Columbia and here.

Russ

[rollandelliott]

those are awesome links!

Thanks! I am excited to start making this.
One company that makes these professionally has a youtube video showing what they think is the most efficient design:

http://www.youtube.com/watch?v=7tk9bmfWHk8

Looks like rain gutter, I think that sheet of corrugated galvanized roofing/sheet metal in the first link would work fine and not be very labor intensive.

Thanks again!

[russ]

The greater the surface area - the greater the potential for heat transfer.

I like the profile they are using - doubt it was made special for them though. Most likely it is available on the market.

I have a small trial thingy I am building - single row of cans one meter in length. Need something to show my wife before I start talking about spending money.

Russ

[flyingdog]

It's amazing how much heat comes out of the simplest of these designs - got my mother using a coil of hose (~200') spray painted black in place of her broken hot water heater (of course, this is in Central Florida). On warm sunny days, the water gets so hot she can't even shower comfortably!

[T-bones]

Amazing Heat...

Many smart people have said that Solar-Heat and Solar-Hot Water are the best way's to take advantage of the Sun.

[Lannyh810]

newbie here

i just posted a thread on here somewhere about this very thing. im making a beercan unit to put in my window sill.
i have my computer fan.....but these little 2 solar cells i bought from "the shack" wont turn the fan.
these cells are 6v,50mA each.
what can i do?

[solarsupply]

it will also helps you to have a cheaper bills

[solarsupply]

if the people apply this they can actually budget their bills especially those person have their big problems in their bills

[solarsupply]

what if the people will cooperate and they put the solar pane l into their window or else they make their own solar technology? i think this is good