[Twi7ch]

Hey All,
I just wanted to post the results of my several months long endeavor trying to heat (at least partially) my rented house with solar. The construction of the panel was unfortunately not photographed but there are a handful of finished and in use pictures.
The Details:
4'x8' plywood with 2x4 framing. Aluminum down spouts sprayed flat black with the grill paint run the length. Sun resistant plastic roofing is the glazing which while a bit cheaper than lexan is a pain to work with and is a bit too fragile for my liking. I have an inline duct fan from amazon that was labeled as a 12V bilge fan for venting boat engine compartments. It's supposed to push 220+ cfm but with all the ducting I'm guessing its a little less. The fan is wired to a $10 snap disk thermal switch set to 90 degrees F so it kicks on over that temp and shuts off below 70F. So far I've seen successful running temps at below 10F it is putting out about 100-110F air at the 200ish cfm. To power this unit and charge my radios I have also put up a Renogy 100W panel and charging circuit to a 75Ah agm battery. The best part is the main draw in this system is the 25W fan and it's drawing when the 100W panel is charging the system so not wasting potential solar which gets used over the dark hours. If anyone has questions I'd be happy to answer. This was a version 1 and I'm planning a version 2 which should be simpler to build and hopefully just add on to my ability to cut oil use. It does a fine job of warming my living area through a wall panel I custom fit and insulated for winter. I'm in northern NH so not the best solar area as it is. Thanks for checking it out!

Twi7ch

 

[Gaowlpoop]

It looks very good. It is very similar to the one I made. It was a resounding failure, not because it did not work, it worked quite well, it was just to small and did not supply enough heat.

 

[cujet]

As always, it's great to see people using solar energy effectively. I'd advise people to calculate the potential solar energy, so they size the system properly.

For example, only a few hundred watts of "peak" heat are available per sq meter at your location in NH. So, a rather large array would be the most effective solution.

Interestingly, some use the thermal mass of a 55 gallon drum of water, located inside, to moderate the temperature. I suspect this probably works well when properly configured. But, being in Florida, I spend my effort trying to keep cool.

Also, it would be nice if the fan were variable speed, thermostatically based on duct air temperature. That way, it runs faster when there is more heat available. And slows down to a "crawl" when some small amount of heat is available.

 

[iconrl]

As always, it's great to see people using solar energy effectively. I'd advise people to calculate the potential solar energy, so they size the system properly.

For example, only a few hundred watts of "peak" heat are available per sq meter at your location in NH. So, a rather large array would be the most effective solution.

Interestingly, some use the thermal mass of a 55 gallon drum of water, located inside, to moderate the temperature. I suspect this probably works well when properly configured. But, being in Florida, I spend my effort trying to keep cool.

Also, it would be nice if the fan were variable speed, thermostatically based on duct air temperature. That way, it runs faster when there is more heat available. And slows down to a "crawl" when some small amount of heat is available.

Could the variable speed fan be as simple as connecting a fan directly to a solar panel? That way the fan would only come on when the sun is shining directly on the panel and fade with the sun.
I would think a small solar panel and a decent PC fan could do this on the cheap.
If the heater retained heat well, I assume you could throw this idea out the window.

 

[TheManComesAround]

Cool project - Especially from someone up my way near the 45th Parallel...LOL.

I'd love to hear more about how much heat you were able to capture through this approach - been thinking of using a similar approach in combination with some sort of heat sink for both a chicken coop and a greenhouse when the time comes.

Kudos!

 

[wtfshtf]

That's a really great idea. Back when I had a pool I had considered running copper tube through a black panel to heat the pool up, however never thought of it for heating the house.

How much do you think it has actually helped? Have you noticed a difference in your gas/electric bill?

 

[arleigh]

As a point of reference ,
years ago I was living on the desert and made 2 systems at the same time .
ON was a 10 gallon water heater tank and the other was copper tubing.
the tank was put in side a double glassed box and the copper was put inside a glazed panel 4'X8'
In the sam sun at the same time they heated water and I examined the temps after one hour of exposure.
The tank provided 130 degree heat and the panel with copper tubing went to 160 degrees .
However the volume of water was different .
The tubing only held about a gallon or so, and of course the 10 gallon tank was full.
To make solar work, you need to protect the heat being generated, from being washed away by the ambient air or wind.
If you get books on solar , there are hundreds of ways to capture heat if your willing to make the investment.
Building the panel is cheap and simple and the best option is to install it before the house water heater preheating the water.
By adding other elements like lava rock or even denser black marble the heat is held longer through the night .
I have seen systems like 55 gallon drums stacked like wine bottles filled with water with a southern faced windows absorbing the sun.
The more southern faced windows the better. (in this hemisphere)

Some folks have made a rock bed in the ground, insulated facing south and glassed over it with insulated ABS tubing to and from the house .
Cold air from the house enters the bottom and the natural convection and heat drives the hot air from the top to the house.
During the summer the whole thing is covered .
If you learn some thermal dynamics you can get cooler air from the same system .
It is helpful to have a good infrared thermometer , remember that it needs to be reading against a surface, "it does not read the air". but free flight paper is enough of a surface to read from.
Heating hot air is easier than heating cold air and vise versa.
The furniture in the house also has an effect on how long the heat/cold remains .
Your refrigerator works more efficiently when it is full than when it is empty. so Keeping water bottles in there pays off 2 ways. (the freezer too).

 

[cujet]

Could the variable speed fan be as simple as connecting a fan directly to a solar panel? That way the fan would only come on when the sun is shining directly on the panel and fade with the sun.
I would think a small solar panel and a decent PC fan could do this on the cheap.
If the heater retained heat well, I assume you could throw this idea out the window.

I'd guess that would work fairly well. Such a setup (small panel and pump, no controls) does work for solar hot water circulation.

 

[Twi7ch]

I have found that it has been similar to my 1500W electric space heater in maintaining the room and only a gradual increase of a few degrees. The benefit lies in that it doesn't cost me any further electricity to run and when I'm not home most days its cranking away heating the small rental house I'm in. The window as you can see in the pictures has a return also so the air gets pulled in at 55-60 and is bumped up to 135-145 on most days when its above say 15-20F outside. It is pushing at a decent flow with the fan I chose. I really don't see the point to slow the fan as it gets less sun since the fan is triggered by the snap disk it has a 20F difference between startup and shut off. It doesn't short cycle and ANY heat coming out is going to be above my preferred temp around 70 anyway. I would definitely need to add probably 2 more panels for the small house to really get hot but I built this knowing it runs during the day when I'm at work and the hours I'm around on weekends. When summer comes along I plan to pull it from the window and I'm going to build a box with screen racks for using it as a dehydrator. The PV panel is plenty to run the fan and my radio chargers which I may eventually add on more panels and batteries to run lights in the living room. I have ideas for improvements and simpler builds that I hope to try so I can add the extra capacity. It's been really cold up here but It's been working even at temps near 0F.