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Solar Heater Box from Skylight?

 
greenhorn
Posts: 9
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I would like to build a solar box out of a small skylight I have on hand, but I’m not sure if it will work.

I would like to experiment a little, build a small box that will go down on my dock (full sun during summer) that will fit milk jugs of water or an insert for a garden hose type radiator water heater.

I’ve already experimented with milk jugs of water, just leaving them on the dock all day and by evening the water is typically warm enough for bathing.  

Primary reason is to use this skylight that I will not be using for any other purpose. But, it is newer and energy efficient. Not sure if it will work.

https://www.homedepot.com/p/VELUX-22-1-2-in-x-22-1-2-in-Fixed-Curb-Mount-Skylight-with-Laminated-Low-E3-Glass-FCM-2222-0004/202038777?MERCH=REC-_-pipinstock-_-202329719-_-202038777-_-N

If I build an insulated box angled toward the sunk, lined with tinfoil, will this skylight heat, or is this application self-defeating, needing single pane glass? Certainly single pane will get hotter, just wondering how efficient this glass really is.

As stated above, this would be primarily used for heating water during the summer for the 2-3 months we have fire season and cannot light fires (when we actually have a fire season, that is, since most summers we don't).  

This is for my project posted here: https://permies.com/t/131778/permaculture-projects/Property-Project

Isaac
 
greenhorn
Posts: 710
Location: In the woods, West Coast USA
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I have a solar oven, and in my lattitude I have to move it into the sun, as the sun moves across the sky, about every 20 minutes to keep it at its optimal temp.  Other lattitudes don't need quite so much attention to it.  It also needs to be raised and lowered as the sun raises and lowers in the sky seasonally.

The inside of my solar oven is flat black, which absorbs the heat rather than reflects it.

The container the water/food is in is flat black, which absorbs more heat.

Does a skylight have any kind of solar retardant on it that might block out some of the heat rays?  They even treat greenhouse panels to make them last longer in the sun.

Low-E glass, yeah, it blocks out a lot of the heat, that's the point.  There might be an old skylight in a salvage yard/thrift store?  But it's just as easy to use a pane of glass.  I have a glass shower door on hinges over a box around an old hot water heater that heats water.  Doesn't work all year 'round, but it's quite good.

I can't use my solar oven in the 3 months of winter, the sun is just too low for too short a time, but maybe if you only need 200F degrees it could heat up small amounts of water.
 
Cristo Balete
greenhorn
Posts: 710
Location: In the woods, West Coast USA
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I have another cheap and dirty water heater for summer/fall, a black plastic storage bin, 1 foot by 2 feet, 2/3 to 3/4 filled with water, and a single layer of a black plastic garbage bag touching the water across the whole surface , floating on it, then extending over the edges of the bin several inches so the wind cannot blow it off or touch the water.  If it's outside in the sun by 10 AM, the water will be quite hot by 4:00 PM.  In spring and fall tipping the back edge of the box up with a 2x4 under it gets it facing more into the sun.
 
rancher
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Location: BC Interior, Zone 6-7
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It sounds like the way we heat our shower water is similar to what you're thinking about.

We have a wooden box with channels cut in the sides at the top so we can slide a single pane window in and out of it. The box is made to fit a small window we had lying around, maybe 16-18" x 24-30"? It's packed away right now, so I can't look.

Inside, the box has a thin ledge of wood on each of the long sides, partway up. When the box is tilted towards the sun, we put a piece of plywood on these ledges. The ledges can be built up with scrap wood as needed to keep the plywood level inside the tilted box.

We use one of those black shower bags you can get for camping to hold the water. We need the plywood level so the bag heats more evenly (only an issue on cloudy days or early or late in the year) and so it doesn't leak water. The opening at the top is not to be trusted, even when plugged.

The wood, inside and out, is just stained with a dark wood stain.

We made this to keep wind from cooling the bag, and to keep heat in the water after the sun goes down. We just throw our bathtowels on top to keep heat in.

It works really well, and can be used on moderately cloudy days in summer, late spring, early fall. It might even work on sunny days in the winter, but we have water on the wood stove by then, so pack the box away.
 
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