Easy Heat from DIY Solar Thermal Panels

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In this video I decided to make a solar heating panel with design features that will be compatible with sky cooling later on. Solar heating is a very efficient method of using solar energy, with the ability to absorb 900-1000w/m2 of heat from sunlight, compared to only 200-300w/m2 of electricity that could be generated from a similarly sized standard solar panel.
Here are a few links to solar fan kits that can be used to complete this project (these are affiliate links):
Amazon: amzn.to/452ivZR
Ebay: ebay.us/T1iV3j
Here are a few links to the videos referenced in this project:
Cooling paint part 1: • How To Make Infrared C...
Cooling paint part 2: • Making Infrared Coolin...
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Thanks everyone for watching!

[@Nighthawkinlight]

Best ideas to improve these panels so far: @bobkins20 suggested tablecloth clips to hold the panel together. This is a great idea! They are inexpensive and durable stainless steel. Multiple people suggested that pink foam board does not last long in high heat and may offgas unhealthy fumes. Aluminum coated yellow foam board would probably hold up better to heat, and the aluminized surface should prevent offgasing into the circulating air. An extra precaution against this could be using an extra layer of cellophane to cover the foam board behind the metal.

[@sl_st]

I wonder what if a thin foil is stretched on the same panel? Then the thermal mass of the structure will greatly decrease. The rate of heat transfer from the paint to the air will increase. 😊

[@sl_st]

I think in this case you will like my design of regenerative ventilation. SL_ST recUperator;)

[@cmbaz1140]

Just a question... how effective would these "heat removing coatings" be if you instead put them inside or outside a radiator or something similar?... You could make it more liquid to fill the radiator or paint the radiator with it... I just wonder?

[@cmbaz1140]

I wonder if dark colored (musou black or something) wool would be the ideal filling material for this project...

[@oasntet]

In the solar oven design community (it's a thing) the usual way around foam outgassing is to paint it with flat black grill paint. It's fairly inert, and a couple layers are enough to stop the gasses from permeating, and it also protects the foam from the heat. Other paints, even the same one you used, might also work just as well if given time to emit their VOCs before use.

[@RageKroc888]

Every time I check in on your channel you're either teaching people how to commit neat science or you're inventing something awesome. May you continue to thrive for mankind's sake Mr NightHawk.

[@Tim88nrw]

I totally agree 💯👍

[@Splarkszter]

Remember to donate to him so he can keep doing it!

[@anonimoqualquer5503]

Its funny to think that in a post apolipse worlds somebody restores the Power in the servers and get acess to some KZbin videos like Nilered and NightHawk and use to build tools and comit warcrimes

[@WarblesOnALot]

@@anonimoqualquer5503 G'day, Nope. Once the Grid goes down, it will STAY Down. And in that Instant ALL Digital Money Evaporates... As does your Internet Connection. In 1933, the Banks in Oz shut their doors, to prevent a "Run" of Depositors withdrawing all funds...; in 1936 they re-opened. My father was working for his father, in a Garage transitioning from being a Blacksmith/Coachbuilder in 1919 to an Engine Reconditioner in 1948...; and they had to contrive to continue trading with Only the Cash they had on hand when the Banks shut down. Thunk about Autobanks EFTPOS Digital Banking... Nothing stored in the Cloud Will ever be Accessible again. If you want your kids to be able to look up whatever you think you know, Write a Book About it, and store the Book Carefully. Squeaking as one who has 3.3k Uploads on YT...; and a book of Poetry published in 1996. The Book is in the National Library, and the State Library, and my Hometown Library. In ten years time, the Books might still be there. Good bloody luck in hoping the Internet will last so long. Global Warming is WINNING. Such is life, Have a good one... Stay safe. ;-p Ciao !

[@Splarkszter]

@@anonimoqualquer5503 * Laughs in self-hosted NAS *

[@noobslayer7564]

The high tech coatings series has been one of my favorite arcs of this channel. Such interesting stuff

[@jerbear7952]

I enjoyed the story arc where he and Ashrel had to journey through Greldenia to find the orb. They may not have been friends at the end but I feel like they respected each other more.

[@potatosalad68]

You must be really hot

[@OceanBagel]

I'd love to see an update video of this panel being used in cold weather, to see how much heat is conducted away into the cold outside air and thus reducing the amount of usable heat.

[@caseyriley1014]

I second this, could you do a short update on it during the winter months?

[@apolloandwarrior_3229]

Yeah, this could be a really big experiment. I know what I'm doing this winter though

[@carstenmenzl5196]

I really like the idea of this panel and love to see how enthusiastic people are about it and trying to optimize! But using the idea of the conservation of energy, the useable energy for heating can only equal the energy of sun absorbed by the surface of this panel. It will turn out, that this energy will drop rapidly in winter time. In addition to that is the medium that transfers the energy just air - wich can not carry that much heat. So it is definitly not enough energy to heat like a living room - sadly.

[@buffalojones341]

You’re one of the best parts of the internet. You create inventions that could be used for patented gain, but you instead share them for free for the world to see. Thank you!

[@aje83774]

A possible clip alternative could be 1" sections of a large diameter pvc pipe with either a slit or section removed to allow it to open and apply adequate clamping pressure.

[@ericgillespie2812]

Happy someone else had the same idea!

[@AdricM]

thirded. but larger pvc, my dad useto have a whole shelf of cheap pvc clamps, i have two that are perfect for holding a lock or knobset into a door while you get the screws in.

[@chrismack7088]

this is a great little design! I built a more traditional one years ago, using wire mesh screening (painted black) inside to increase heat transfer and it worked incredibly well, but was significantly more expensive to build, and was quite a bit heavier with wood frame and plexiglass. Genius idea.

[@maglev_]

i love how many of your projects are basically purpose made to be as simple, doable, and open source as possible. all your videos are entertaining and relatable for the common man just as much as for the science nerd. keep doing what you’re doing its great stuff!

[@drewcress]

XPS foam board is great for the cold and wet but has some limitations when it comes to heat. It stats to melt at 70c and is combustible - probably not desired in a solar heating panel. Polyiso performs better in this temapture range, often comes with an aluminized facing as an added radiant / vapor barrier, and at roughly the same cost. The alu layer pointing inwards will likely act as a heat sink/spreader (given the limited air space within) and increase performance as well. If the expected lifespan of the film is just a year then shipping tape should be able to handle that while being replaceable in the same time frame. This would make the screen frame largely optional (but sooo much easier to work with for prototyping)

[@SteveEh]

Just did a bit of research on plastic types to use for the covering. My first thought was clear "shrink plastic", for draft protecting and winter insulating windows. Turns out, the type of plastic, from what I can find, Is IR blocking. Polycarbonate would be a good option, but expensive. Greenhouse plastic (Polyethylene Film) has all the right properties, UV resistant, high IR pass-through, fairly inexpensive. Good luck to anyone building these panels!

[@mitomon]

I'm an hvac contractor so I'll build a couple of these in the winter and hook them up to my system, check the results, and report back

[@toastedbacon1219]

its been eight months how did it go?

[@mitomon]

@@toastedbacon1219 my part of texas did not have a winter this year. Will have to try again next year

[@tiberiusmagnificuscaeser4929]

One of the potential uses for your cooling panels would be as an atmospheric water generator, cooling down a surface below dew point allowing water to condense on its surface. It would probably be a lot more efficient than ordinary AWGs that just use regular white paint I’m pretty sure.

[@NotWorkingAtAll]

This is a great use. I just saw the hydropanels that use desiccant to help pull the moisture out of the air. Combining this cooling solution would greatly enhance its capabilities.

[@tiberiusmagnificuscaeser4929]

@@NotWorkingAtAll Interesting. I realize now that I was thinking of air wells, which are a similar technology that use a thermally isolated panel that cools down during the night allowing dew to form and be collected.

[@Bigman74066]

The increase in temperature difference in the second setup is partly due to the decreased air flow. To het a better picture you should also measure the airflow...

[@sportsfamily77]

I feel like these panels would be a really good addition to a greenhouse during winter. With enough of them you could probably get the temperature high enough for year-round non-cold weather crops in zones four or five and six.

[@SteveEh]

If you combined these with liquid heat storage, this could be amazing. A closed loop liquid pumping through the back of the panel and inputting the heat into IBC's for overnight heat release.

[@sportsfamily77]

@@SteveEh that would be a great diy thermal battery!

[@MrScorpianwarrior]

@@SteveEh I wonder if you could repurpose a water heater to use as a thermal battery? They are already incredibly well insulated and designed to store heat. I have never purchased a water heater but since it wouldn't need the gas/electric heat system you could probably buy a broken one pretty cheap. Or start a company repurposing them? That one may be a little far lol.

[@2nd-place]

That’s what I intend to use this project for, once I actually get around to building the greenhouse for my wife. Will probably integrate it into the design seamlessly, as a sort of awning across the front that tips down angled to the low, southern sun in the winter. Then you get the heat through the glass for autumn and spring with a valve/fan shutoff switch that can be enabled for additional heating in the winter!

[@cupbowlspoonforkknif]

Look up "passive solar greenhouse". The problem is not heat during the day but at night. The solution is a subterranean heating and cooling system. You run air pipes through the soil underneath to use as a thermal battery. You can keep it from freezing year round in some pretty cold places.

[@ZoonCrypticon]

You could build a changing surface for the outer facade of a house with a simple already known techinque: trilons (like for billboards). A trilon surface in black (for winter time) a trilon surface in white (for summer time), and one colored in your favourite color, if you plan to invite guests, when the sky is cloudy. The airflow could be managed within the trilons. At the same time it would be a good insulator.

[@emeralddiscordian3116]

Panels are easily retrofitted, but with a new house you could have the whole roof be made out something like this like this. Though, I think only one side of a roof would probably be plenty. It would be interesting to see how effective the white paint would be.

[@robinyilmaz1155]

From the thermal imaging, it seems the air already reaches its outlet temp halfway into the panel. Which means, you can increase the flow rate without losing outlet temperature.

[@johnkolb3871]

Was thinking that also. I’m not a great programmer but I was thinking that you could mount a thermistor on the output air and compare it to another measuring the max temp of the heat collector. Use the difference to control the fan speed. Not sure if the efficiency gains would offset the power requirements of the fan controller, but worth a shot?

[@ElectroBOOM]

Great project! A question, wouldn't painting the other side of the metal panel black also help radiate heat better to the air passing over, as in dark body radiation? Or maybe it makes the thermal conductivity worse...

[@Nighthawkinlight]

Yes it's possible that painting both sides would be an improvement

[@Quephara]

The only reason I'm leaving a comment here is to send a notification to two channels at the same time

[@Hendlton]

If I recall correctly, Mighty Car Mods tried painting a car radiator black and they managed to lower the coolant temperature by like 1 degree. The conclusion was that it's not worth it.

[@nochalnosowski]

Have you heard about Stirling engine? Panels like this could power it

[@ultrablazed9126]

@@nochalnosowski this could be a good idea for a small scale demonstration but i doubt you could get enough torque to do anything

[@D4no00]

I would love if you would make and update on the panels in the winter and their actual performance when we talk about heating a room, maybe even using a few of them at the same time.

[@vedranart]

This! Id like to see it in daily use and how to actually set it in house...

[@kvg4790]

The heat transfer rate difference between turbulent and laminar flow conditions is due to turbulent flow’s larger Reynolds number. This isn’t always the case though. I was lucky enough to have Ephraim Sparrow as a professor in college. He’s better known for his pioneering work in radiant heat transfer (I have so many stories and on his teaching that), but he also did some work on laminar reynolds numbers. He was able to get laminar flows (water) to have reynolds numbers greater than 32,000. A story relevant to your cooling paint: Eph was working for the US government in the 1940s or 1950s where they needed to put sensitive electronics in metal boxes on the top of telephone poles in the Nevada desert. The electronics kept failing due to the high temperatures and the requirement that the boxes had to be completely sealed. I’m guessing that these were sensors for the nuclear tests done at Los Alamos, but he specifically said that he couldn’t talk about the specifics because it required a security clearance. Well anyway, His boss said, “polish the box exteriors to a mirror finish” and Eph replied, “no that won’t work, paint them white.” When asked why, Eph responded with “it’s intuitive.” Well, that didn’t go over well and while he didn’t go into the specifics, he was fired and his boss told him his idea didn’t make any sense. Fast forward 10 or so years and he ran into his former boss at a convention or a presentation and his boss apologized and said that Eph was right about the white paint. But that’s why Eph is basically the father of radiant heat transfer theory.

[@PulpParadise]

Great story, thank you! I know that white is reflective, but I always thought that a polished metal surface would surpass it in cooling effect.

[@ipissawesomeness]

I love watching this guy, he's like a woodshop and chemistry teacher combined

[@scott98390]

They sell pre-made support strips for the corrugated metal panels. You could add them behind the metal panel to use as both supports and walls to force the air to take a longer path

[@Nighthawkinlight]

I thought of that but home depot didn't have the right pattern to fit this style of panel

[@oldskooljules]

@@Nighthawkinlight Even when they're available, the cost is way more than it ought to be. The cost of cut foam is SUCH a racket.

[@wingnutbert9685]

@@Nighthawkinlight Cut your own out of the XPS. Cut a strip a couple inches wide, of the corrugated metal. Mount it on a straight strip of wood with an inch of the metal sticking past the edge. Use to either press an out line in the foam to cut with a *insert your preferred tool* or, if the metal sheet is strong enough, use it as a shear like blade to cut the foam. Maybe even use a torch to heat the corrugated to cut through the foam like butter. (Probably better with a piece of angle iron, or similar, for mounting the corrugated strip to for torch proofing better than wood, but wood will likely be ok if directing flame just at the edge.) Maybe even go all out an turn the corrugated sheet strip into an electric hot wire like real foam cutters use.

[@lannyvermette7147]

I would as do some test to figure out what the optimal amount of baffles would produce the most amount of heat. Of course this number will vary depending on the build. I suspect Ben would have gotten better results using more than 3.

[@bobkins20]

What about using table cloth clips? They are available in different sizes and pretty common.

[@Nighthawkinlight]

Excellent idea! I did not know those existed

[@user-mh3ws1ol5c]

Or just use good amount of duck tape even that will work for sometime

[@bobkins20]

Also m.youtube.com/@GScottDavis has been using multiple layers of black hardware cloth to create an absorber wich the air flows thru. Gives plenty of surface and turbulence for the air to get heated.

[@Sashenke]

Duck tape glue usual handle sun quite badly

[@user-mh3ws1ol5c]

@@Sashenkeyha that's why is said for sometime

[@HGS9773]

Your fabrication here is slick with today’s materials. Only as a point of interest, about 50 years ago, I built a similar wooden box to yours using regular tin cans spaced apart inside, all painted black. I used plexiglass for the top of the box. The box, with one end open, was propped on outside wall at a 45 degree angle and secured under the open window sash all insulated against cold air intake. Worked fine! Some home made stuff becomes classic! Keep on goin’!

[@pedrocx486]

Someone probably already mentioned, but for the clips, I think 3D printing would come in handy - especially if printed in PETG. (PLA doesn’t last when exposed to too much heat and UV radiation. I remade most of my “outside” projects in PETG and durability has been nice.)

[@ashurean]

I think heating & cooling panels, reversible heat pumps, and shared geothermal ground loops are the technologies I'm most hopeful to see become commonplace in the near future.

[@justinw1765]

I have some ideas for more efficient and lower cost geothermal designs. Involves using a water pressure washer to "dig" holes into the earth (in my area to around 9ft or so deep), placing essentially giant "heat pipes" into these, and insulating them in key areas. Heat pipes are often used with computer systems to help cool them. They do this by combining copper tubes with some kind of inner wicking material, a small amount of water, and as they seal it up, placing these under a vacuum to lower the boiling temp of the water. Between the copper's high thermal conductivity, and the water phase change from liquid to gas carrying tremendous amounts of energy, these become something akin to like super (thermal) conductors (in the loose sense, not in the usual sense of the term). Then these large "heat pipes" in the ground are wrapped by regular copper to which water flows through from an insulated tank near them (and coated white in the summer and black in the winter. Or placed under the house like in a crawl space). The copper tubing is again well insulated in key areas (and once you get off the heat pipes themselves, you could switch over to some other cheaper and less conductive tubing). The combo of all the above may dramatically lessen the space and volume of material needed to efficiently cool/warm the water depending on the outside conditions. The part of the heat pipes at the very deepest part of the ground, would not be insulated, but again, key parts of the rest of the system would. Of course, as you get closer to the surface, you see more and more temp fluctuations and range (insulation would help to offset this). All the copper pipes and tubing of course would need to be thinly coated inside and out to maximally preserve their life and slow down oxidation (especially since this system will be buried in what for most will be damp soil). The main challenge is getting a high enough vacuum in the copper pipes to reduce the boiling temp down enough so that the phase change takes place readily. You would have to get it in the 29.2 to 29.3" Hg or so range. Filling the copper tubes partially up with some highly thermally conducting material that is non reactive to water and copper (graphite?) might also help in the overall process some as well?

[@trynadyna9662]

Man thanks so much for sharing your knowledge over the years. Your channel is so amazing and you are such a cool and interesting person. I hope you understand how much you are appreciated, and I hope that you receive a lot of fulfilment from the joy you bring to others. Thank you, sincerely.

[@Nighthawkinlight]

Thanks!

[@irvalfirestar6265]

An easy and cheap way to substitute for the gutter clips (and is way more available globally) is by using 4 normal ratchet or luggage straps, installed on the edge lengthwise, which cuts down on the number of unwieldy clamps you would have to use to maybe one per side instead of 2-3. Or just cut a tiny bit of efficiency off and apply 6 straps in a grid pattern across the panel.

[@geordonworley5618]

I highly recommend using a fluid to air and fluid to fluid heat exchanger to avoid any buildup of dust anywhere in the panel and increase heat exchange. It is very easy to make your own heat exchanger. For instance, you could just coil two tubes around each other for some length to increase their contact. At one end everything is hot and one end everything is cold. Fluid from the panel goes in the hot side and out the cold side. Fluid in the medium being heated goes in the cool side and out the hot side. This is going to be much more efficient as it will not bring the temperature of the fluid in the panel loop to equilibrium, but to the same temperature as the media you are heating. For cost I would recommend water (ideally distilled) for the panel loop. Since it will be a closed system, you wont need to worry about buildup. Opaque tubes will prevent the growth of algae inside. Again, I highly recommend doing it this way, and it will increase the panel's heating or cooling capacity. Air is not going to conduct heat as well as water and a heat exchanger will really help increase the overall efficiency, ensuring the maximum temperature delta of the fluids possible.

[@ehombane]

Also, fluid heating makes sense for good weather. You can use it for washing. But air heating is kind of useless. in this nice weather sure is warm inside too. Unless is winter, the weather is sunny, but air freezing. Then the temperature loss through that plastic will be tremendous, and wonder about efficiency. Maybe 3 or four more layers 2mm spaced will help with good efficiency. Also, with liquid yo can store heat, so you can use it for the night too. Anyway, I am really interested about efficiency. We see here 30 degrees for that half a meter panel, but is warm outside. If outside is below freezing, I will be able to add some heat inside? Especially if I have trees that block some of my sky view? I intended to play with a heat exchanger, to save some heat. But the heat lost opening the windows is not so dramatic. With commercial heat exchangers I am sure that you never recover the investment. With one manually made, I will waste only some time and some cheap material. Still not sure how much I save on heating. But If I add such a panel outside, for the two hours I have sun on my windows in winter, maybe it is worth bothering with the system. A system with vacuum tubes, sure will be efficient, but not sure about recouping the investment. Those damn tubes are too expensive.

[@SkyGizmmo]

Very good point in the medium of transfer. The plus being is that it could be routed to tank storage heat “battery” even supplement hot water. Thanx for great comment and a return to QUiET radiant heat. Spinning fans and emf creation is a good trend.

[@Urammar]

You're like an actual legend, anyone ever told you that? Just keep on being you, good sir.

[@clownwreck]

You might want to try reversing your fan, so that it pulls air through the panel rather than pushing air into the panel. I've found that, at least in the case of my own home, using an exhaust fan moved air better than an inward-blowing fan. I'd be interested to know what difference this makes in your results.

[@ikocheratcr]

If you do that, the fan will be exposed to higher temperature, and will decrease its life time, and maybe even run at lower speed if the control IC is of the type that reduces speed if it is too hot. Fan are expected/designed to suck cold air and push it towards hot surface.

[@justinw1765]

If we're serious about using this for home use, what I would suggest might be easiest, is to put a foam panel insert to fit in an open window with a hole cut in it to allow for some hose or the like to connect. And at the inside of the house, install a little fan over/in that hose, pulling the now heated (or cooled) air in. This does a few things simultaneously. It allows the air in the system to more gradually heat up (or cool down), helps to the keep the fan cooler in heating mode, keeps the fan from being exposed to outside conditions, allows you to easily connect to an energy source (outlet inside), and easily disconnect it whenever you want or need to. In fact, at night time, you can have an insulated flap or the like over this while the fan is off, to minimize heat loss (or gain). Speaking more generally, you wouldn't need a particularly strong fan for this. There will be plenty of natural convection through the system as the hot air rises and cool air is pulled in from the bottom. Just need a gentle fan to help it all along. The fan will become more helpful and necessary when you are reversing the system to use as as cooler.

[@BokoMoko65]

I suggested the same the Ng later. Haven't read your post. As for exposing the fan to higher temperatures, don't bother. This kind of fan is built to work in these conditions

[@blurglide]

@@justinw1765If the foam is obstructing a window, all it's doing is adding an extra step to thermal radiation that would've entered the house anyway

[@justinw1765]

@@blurglide Obstructing the window? What I meant was, you open up the window and in that open space that you measure, you cut and place a corresponding rigid foam insert. Ironically, if you use 2" or so thick foam, that part of the window will be far more insulating (in a conduction and convection sense) than the rest of the window for most folks (unless you have very expensive/specialized windows i.e. vacuum insulated glass windows). *If you're worried about IR transfer through the foam, just put some foil, mylar, or the like on both sides of it.* And as mentioned earlier, you cut a round hole into that foam window insert to connect a hose to. That hose is connected to your Solar heater/IR-space cooler. The fan goes inside that hose, from within the house, for the reasons I mentioned earlier. I have experience with this. We have a shed out back that was converted into an art studio/sometimes guest room. In the summer, we put a portable, upright, on floor A/C in there. The AC hot air exhaust hose is connected to a rigid foam panel that inserts into an open window. It works fine and is worlds better than those stupid thin plastic side flaps that come on window AC units (I call these stupid because they do indeed allow a lot of thermal exchange between the inside and outside).

[@ecoista1373]

Hi Ben, love what you do. I talked to my brother who is an engineering professor in a university, to maybe do bachelor on science and technology and hope to reproduce some of these experiments you have been doing. They really need it where they live (east amazonia), it's so hot people don't get out of their house there past 10 am to 4 pm, only people with air conditioner on cars. I went there this July and got sick very fast from the heat and dirt. I remember walking those streets with no one but me and an umbrella that didn't provide enough protection for me, as I got sunburned. I heard in the US there are places where they're applying sun shield on the asphalt because of so much heat. Times are changing and the hotter the world gets the more creative we should be. Thanks for your video! I only imagine how rewarding it must be to receive so many positive comments on your videos, that you truly deserve, and hope one day the world wakes up to care for our common home

[@sparrowthenerd]

I've gotta say, you have the most engaging sponsor section of any KZbinr I watch, purely because that darn bird makes me keep watching 😂 I can only assume it's intentional

[@OmegaWoodworm]

There are a couple other really simple things you could do to improve the efficiency of these panels: Mount them vertically-ish (30° or more from the horizontal should be fine), so that one inlet/outlet hole is at the top and the other is at the bottom. 1) If you are using a fan to circulate the air then make the top hole the inlet so that the cool air has a chance to recover some of the waste heat from the hotter air coming from the outlet side below. 2) You could alternatively get rid of the fan entirely by having the inlet at the bottom and outlet at the top, allowing convection currents to circulate the air for you; this will reduce total airflow but also causes the air to spend more time picking up heat on it's now leisurely journey around the baffles.

[@Pro_Triforcer]

I'm pretty sure the air has more than enough time to pick up heat. The thermal camera shows that most of the panel is hot, meaning that the air gets just as hot before it even travels halfway through it. I'd suggest more airflow.

[@kreynolds1123]

@@Pro_Triforcer Thermal imaging is imaging energy escaping. The hotter the thermal image, the more heat energy is radiating away. Increasing the airflow generally increases the solar thermal energy collection efficency. I might instead recommend letting cool house air into the space over a reusable air filter material spray painted black. Then force the air through the painted filter. The filter's top layers give up its heat to the cool air flowing over it while sunlight that penetrated the filter's top layers is absorbed and trapped as heat unable to radiate and having a high surface area and low heat capacity, readily gives up its heat energy to the air flowing through. Top and bottom manifold might aid in spreading the airflow more evenly. Avoid materials with a high heat capacity. Because a solar thermal collector needs to move the heat inside or to a heat storage unit inside, quickly to be more efficent.

[@kreynolds1123]

@@Pro_Triforcer counter intuitively (to most anyways) a solar thermal pannel is more efficent the cooler the hot air is due to increased airflow. That is, one gets more energy out of a collector when it's output temperature drops because of rapid airflow. Although, I think it's Important to recognize dismishing returns with increasing rates of air flow.

[@dsmoke1972]

@@kreynolds1123 @Pro_Triforcer moving the fan down in a duct would keep the airflow but not cool the air as it exits the collector

[@kreynolds1123]

@@dsmoke1972 One may certainly place a fan in the ductwork as you point out. But reguardless of where it is, a fan pushing twice the volume of air over a given period heats twice the mass, but a given flux of solar thermal energy over the same eriod means the exhaust ends up cooler (not as hot) as when air is pushed through at 1/2 the volume over the sane given period.

[@MuttMuttOutdoors]

The issue with the foam board is that it will need to be protected as the heat will break it down. I built a "tin can" collector in a similar fashion using foam board on the back and sides as well as creating a channel to force airflow through. Long story short much of the foam broke down quite quickly but it worked pretty well. It was only 24"X48" but I was able to keep my living room pretty warm. I inserted a temp probe into the solar collector and then inside I had a fan inside that would be turned on when the collector was over 80 degrees or so. I built an insulated insert that was placed into a window and secured using some cross boards and toilet flanges to attach to both the collector and window insert so that I could attach some insulated ducting. But using the foamboard you will notice a plastic smell the more it breaks down and I would say it's probably not all that healthy to be breathing. You could easily build a box and place the foam on the outside then cover with something else to protect the foam.

[@Nighthawkinlight]

Thanks for sharing your experience! I didn't think about the foam offgasing. An easy fix would be to add one more layer of cellophane on top of the foam and behind the metal.

[@MuttMuttOutdoors]

@@Nighthawkinlight I understand, I didn't think about it either but have been in the process of rebuilding a house and after stuffing R19 in the wall cavity I capped it with R10 foamboard so had some pieces left over that I figured would work well. Most of the foam in certain area's has broken down to nearly nothing due to the heat buildup even though I was using a 195CFM fan to push the air through the box which was only around 4cu ft. Even with ducting losses and such I was probably changing the air out once every couple of seconds. I personally think you need at least a skin of 1/4 inch wood to protect the foamboard though. It's not just the off gassing you are worried about but also the degradation of the insulating properties and strength. My next build will be 48" X 96" on the outside with a 1/4 inch skin on the inside and outside of the box with the goal of it providing most of the heat for the house.

[@johnkolb3871]

I had a similar idea about a fan controller! Glad to see it works for you!

[@MuttMuttOutdoors]

@johnkolb3871 my temp sensor is an esp8266 running esphome hooked into homeassistant and the fan is controlled by a Sonoff basic also running esphome. HomeAssistant is running nodered for the control function and it seems to work quite well. It also checks the room temp and if it's over 72 it doesn't turn on at all.

[@cimachu]

Awesome video Ben, I love how you walk through your design process without dragging it out or making it boring. This video sort of reminds me of some of your older ones because its something that anyone can make, and that I can imagine a lot of people would want to make, but maybe that's just me. Cheers!

[@marklefler4007]

Great video. One thing, the shiny back of the painted panel reflects is making it act like a radiant barrier, meaning it only emits a fraction of IR. If it was painted black also, it would radiate much more IR, heating both the air that touches the panel (via conduction and convection) as well as radiate to heat air molecules which are not directly touching the panel. Also as you mention the polyethylene passes IR, so so a lot of the heat on the black painted panel will radiate out through the film. Glass or an IR opaque film would work better in heating season. I suggest two films, IR transparent for the "cooling" side and IR opaque for the heating side.

[@ki4dbk]

I like how you started with a module to teach yourself basic panel building. I remember when you started, with just a few fun pyro vids, like the sodium metal in a can stuff. Like 10+ years ago. Thanks for lettin' 'Prince Albert' outta the can. Great content!!! 👍

[@Sashenke]

In place of plastic clips you can use stripes which wrap around panel. Of course it would steal some heat (by absorbing), but should keep structure tight.

[@gregcarlson6496]

You are a cool dude. You are one of those videos you get straight to the point without the 45 minutes of blah blah before sharing what you want to say. Keep up the good information for us viewers. Your cool

[@jasonmorello1374]

You might consider paracord bands, using a crossing in the back pattern, and changing from horizontal to vertical across the corners, you could do with possibly one continuous and somewhat reusable length. If it is going to get a lot of sun and weather, clothesline could do enough, and there could be tying strategies to cross the center if more tie down is needed. Those plastic clips will degrade in the sun as bad as anything, and a dollar store clothesline might do more than one panel.

[@PlayNowWorkLater]

Nice to see you being active again. I've followed you for years, and you have such a talent with creating content that is both interesting and accessible. I love that it is reasonably priced, simple and an explanation that is simple and easy to follow. Thanks again for doing what you do. You are an inspiration to people like me who are making a go at making our own content.

[@cupbowlspoonforkknif]

Always paint exposed styrofoam!(not with spray paint! Use a mini roller) It protects it from breaking down in the sun. I have a painted foam panel on my greenhouse that's held up for 2 years now with no sun damage. I would ditch the pipe foam sides and just use wood or rigid foam. You don't have to deal with weird clips. You just need to use some form of washer so the screw head holds into the foam and doesn't tear out. You can use thin scraps of wood to act as washers.

[@solarsynapse]

Liquid rubber is a good durable coating.

[@thehazelnutspread]

Suggestion: instead of the plastic film that you used, how about using clear landscape poly. It has UV protection and would probably last 5-7 years.

[@leifhietala8074]

I was thinking the window insulating film that's intended to install outdoors. Similar UV protection and absolutely clear.

[@marcelihryniow211]

This one will become a classic (for me at least). One of the most useful, interesting, easy and thought provoking videos I watched in a while. Thank you for all your work

[@unionse7en]

People have done a much more optimized version of this with pretty thorough testing, the winner so far is 2 or 3 layers of charcoal window screen above the black backing sheet...(possibly the backing heat should be reflective or it may not matter as nearly all radiation should go into the screen) . The screen is set at an angle to that all of the fan blown air has to pass through the heated screens. Screen has a lot of surface area. Cost effective designs are bases on what glass doors etc you can get for cheap.

[@johnkolb3871]

Interesting! Can you suggest any links?

[@FainTMako]

Links?

[@ibrahimkocaalioglu]

Nice work as usual. A more expensive but more sturdy design would be to use copper pipes and make it S shaped pannels. Paint it black it would be a perfect heater. It is what we use in Turkey to heat water at the top of the building.

[@justinbanks2380]

Any time I see you've posted a new project, I know I'll be both surprised by whatever you choose to do this time, and that it will be absolutely brilliant. This is no exception! I always learn so many things from each of them, but am amazed that one person can attempt and accomplish so much. A true inspiration! Keep being you!

[@amythompson6869]

Are you by chance a science teacher? You have a fantastic way of teaching,speaking,& are very knowledgeable.

[@Nighthawkinlight]

I am not, but thank you!

[@kurtlindner]

Man, I love your content. When it comes to science creators, you're *S++* tier. Mark Rober is fun, William Osman is funny, Nile ROYGBIV is great, Neil DeGrasse Tyson is a genius, etc., but no one else is Night Hawk in Light. 👏🏻👏🏻

[@_kalia]

I'd love to see you combinie the heating and cooling panels to power a stirling engine. I already love the idea of it for home heating/cooling, but I'm curious if it could provide any usable amount of mechanical or electrical power too.

[@Luciferkragoth]

omg yes a sterling engine experiment would be amazing.

[@AlanTheBeast100]

For usable amounts of power from a Sterling engine you would need very high "quality" of heat: high temperature difference in the air and high volume of that hot air.

[@ruskokollektiv5457]

@@AlanTheBeast100 well, if you ran both heating and cooling panels at the same time, and funneled the outputs to small spots, it might work. The issue is temp differential, like you said, and having both sides working gives you better efficiency. You might even be able to create a dual closed-loop system with liquid coolants to transfer heat most efficiently

[@MrScorpianwarrior]

I was thinking about this, but I don't think it could possibly be a more efficient use of energy than a normal solar panel. That being said, there are solar panels that use the excess heat to generate energy so maybe this system could be used to improve efficiency there?

[@curtra8288]

This village is doing some interesting things with solar heat storage and their own Stirling engine design

[@RyanLebeck-td5ft]

Two part panel where the front and back panels can be swapped in the relative seasons: radiant thermal collection during cold months, and thermally depleting panel for hot months.

[@shazam6274]

Interesting! What's even more interesting are the "Shorts" you're releasing which are edited down shortened versions of old videos. They reminded me of older favorites, so I re-watched them. So... then I went to the YT channel and sorted by "Oldest" first. WOW! I've been watching you over over 10 years! Great stuff ! Thanks.

[@ethanhenneberry2625]

I started watching this channel back around the time of the mini cannon, bottle rocket (not sure if that is what it’s called, I remember you launched a 2l bottle off of some sort of pvc frame) and paper crossbow, how many years later I still always look forward to your uploads. Keep up the good work, I greatly look forward to what the future holds for this channel!!!

[@kreynolds1123]

On just efficency of heating forced air, one could simply spray paint black on a reusable air filter material. Then let cool air in over the top and force it through the fibers to the back so as to cool the top fibers that reduces radiative losses while sunlight that penetrated deeper is absorbed and converted to trapped heat untill it's disipated by heating up the air flowing through. The next major focus should be on rate of airflow. The more air you pull or push through, the less radiative losses resulting in higher solar heating efficency. Lastly sone consideration nay be given to where to let air in and where to pull it out from to aid even cooling of the filter material. Recycle pre-filter indoor air is recommended. It may be better to optimise a system for heating, or cooling rather than do both.

[@Dinnye01]

I smell another Tech Tangents followup for this. I really like how you inspire others to do great things.

[@andysheepleton]

Black screens work very well you can stretch multiple black screens inside the box and have a black back behind the screens.

[@_jocker_games_]

Similar design can be used for passive water heating, just connect it to a barrel. We use this system to preheat water from a well because we already have barrel at attic witch we use as water tower.

[@Spectre4490]

In Tureky i saw similar panels, but they made with tubes filled with water, it was at 2010

[@Eagle3302PL]

@@Spectre4490 Been to Turkey this summer, pretty much all homes have these water heaters.

[@user-mh3ws1ol5c]

U can even use the same heat to heatup water too by some adjustments Or by using the hot stream u can even use it to a small wind turbine to generate electricity Everytime i get to learn something new from u thanks for sharing your knowledge And that 🦜 is really cute 🥰 🇮🇳🙏🕉️🙏🇮🇳

[@reverse_engineered]

If you wish to heat up water, it's best to heat the water directly rather than heating air first. There are many examples of solar water heaters that use a similar style of box, but have long runs of black tubing within them that the water runs through. Similar to how the black sheet metal transmits the heat to the air behind it, the black tubing transmits the heat to the water within it.

[@wiretrees]

you are the definition of scholar and a gentleman

[@gabewrsewell]

awesome awesome work. i’ve been watching your channel for about 10 years now, i think you’re my favourite project channel right now so i’m thankful you’re posting a lot lately. one of your biggest strengths is whittling down a project or idea down to the most efficient, cost effective, and easiest iteration :) keep it up!

[@emilalmberg1096]

I am following this with interest. My off-grid summer cottage needs help to extend the season spring and autumn. The heater you have built is similar to the solar fan that I already have, and is quite common in Sweden. I'm looking for that little extra, which can push a little more heat into the house, then you probably have to have a color that is not only black, but also doesn't radiate the energy again. -That's where I hope your genius can help!

[@dave7038]

There are some neat designs for room heating using solar thermal panels. One that I thought was particularly clever was a masonry wall with a tall recessed area on the sun-facing side over which was installed a glass panel to form a chimney-like cavity. The masonry behind the panel was painted in a dark color. At the top and bottom of the recessed area were vents on both the outside and inside. During the winter when heating was desired the top and bottom vents inside the room were opened, and convection would draw cool air from the floor inside into the cavity to be heated by the sun and returned to the room via the top vent. Alternatively, the bottom exterior vent could be opened instead to draw heated fresh outdoor air into the room. The masonry served as thermal mass, allowing the wall to continue to add heat to the room long into the night. In the summer the vents could be reversed with the lower vent opened into the room and the upper vent opened to the outside so that warm air was drawn out of the room, with makeup air coming from the cooler outside air on the other side of the building, which was shaded.

[@emilalmberg1096]

Yes, all suggestions should be considered, we may find methods to help our houses heat themselves. What you describe is not so different from a solar fan you can buy today. You also have to find ways to expel moisture, and not accidentally add more moisture to the house.@@dave7038

[@alexcivitello3165]

I think a more permanent solution than the flexible plastic sheet is going to be required if you have any hope of larger scale adoption. Many setups like this are gong to be deployed in hard to reach locations. The lower maintenance cost, the better.

[@6rusT]

Wow, these types of videos are the ones that should be the most popular and the ones that should be made the most. They have incredible value for less fortunate people in countries where purchasing power is not high. Bravo for your videos!🙏

[@Clark-Mills]

Heat wants to rise and having your zig-zag vertical creates pockets of resistance where you are fighting gravity. If you rotate your assembly 90 degrees so that the heat rises you should get improved flow as you are working with gravity. Very nice work and well presented, thanks!

[@timschafer2536]

I actually would have used water instead of air so you could connect it to your central heater and radiators and in general to have smaller ducts.

[@corcorandm]

Antifreeze might be better

[@integza]

Awesome project! Do you have any idea on how to store extra heat ?

[@Nighthawkinlight]

The best ideas I've heard involve a material with a phase transition just above room temp. Using the heat to melt a barrel of wax is one of the better ideas I've heard

[@pieandpeas8929]

A sand battery would be well suited. Just need to optimise the shape.

[@SeattlePioneer]

(Repeating a comment I just made...) I've developed methods for heating water cheaply that work for me. In the winter, water is heated on my wood stove. During the summer, I have a method of solar heating water. I simply painted a couple of two quart plastic jugs black. They are placed in a hollowed out Styrofoam block that would otherwise be waste. This is covered by a glass panel salvaged as shelving from an old refrigerator. That gives me water that varies between a temperature of 120-160 degrees F depending on how hot and sunny it happens to be here in Seattle, Wa. I typically use about two quarts of water for dish washing and two quarts for bathing (sponge bath). I also collect a couple of quarts of hot water in two one quart thermos bottles for off peak hot water use. This commonly provides for all my hot water needs during the summer months, but if I need more or the days are cloudy, I'll just heat up a saucepan of water on my cookstove as needed. A major unstated part of this method is the frugal use of water. The typical floods of hot water used for dish washing, bathing and such are not my practice, and I use water collected from my rain barrels and have not used citiwater for many years. Of course this could easily be expanded to additional such collectors if desired. A major advantage is that they are virtually free, using salvaged materials. Only the black spray paint to paint the jugs was purchased., Of course this is labor intensive, since it requires setting out and collecting jugs on a daily basis. However, these things, like collecting the water, are hobbies and activities I enjoy doing.

[@Spoon80085]

If all else fails you could just convert it to electricity with a stirling engine

[@1a1u0g9t4s2u]

I have used a 4" or 6" PVC pipe cut into 1" rings (thickness may change to get various compression) Cut a small section out of the ring to make a "C". Clamp is now complete. Thanks for sharing.

[@Splarkszter]

If anything involves heat and/or sunlight, avoid plastics as much as possible because they degrade extremely easily. Also the toxic fumes they emanate. Glass and oiled wood are our best options. For the fan, make sure to use one rated for static pressure, not so much for airflow. And please please please avoid aerosols, the ozone layer stops lot's of high energy UV frin the sun, we need to protect it. Anyway, thank you a lot for your sharing of knowledge. Please people remember to donate to this awesome person.

[@GoingtoHecq]

I wouldn't use foam for anything that I wanted to last beyond one year, but it's still a great video on the basics of heating panels.

[@Spy653]

I have 3 inputs for you (just cause I know you read these which is fantastic): 1) I would suggest, rather than using the pool noodles to space the panel, you should/could have the corrugated metal sheet flat to the bottom panel and cut small pockets into the foam back board. This would cause the air flow to be routed through all of the folds whilst also involving minimal tooling. 2) Also, if you paint the other side of the panel white it will increase heat transfer from the metal to the air. If you've ever accidentally bumped a towel rail you'll have discovered that chrome/shiny materials radiate extremely poorly and dump all their heat through conduction. 3) finally, why not use cellophane instead of clips to hold the panel together? It's used all over the world to wrap pallets every day and on the finished panel you shouldn't ever have to open it back up! Best of luck, I hope these have been thought provoking at a minimum, and that we get to see more of you soon!

[@Spy653]

I also wanted to briefly thank you for all your bits of wisdom over the years. I can't count how many times I've used buttons to build sheet forts for my daughter to play in.

[@breannestahlman5953]

I've already wathed your video a while ago but I forgoted it, now that I have a little more hours of watching on the subject I appreciate much more your video value. Thanks a lot. I think your solar panel is the most valuable of all that I watched.

[@gdcakaban]

You have a very good narrative and voice to let people absorb what information you are presenting. It sets you apart. Cool.

[@djmikio]

The KZbin algorithm was probably trying to assist my radiant floor via solar heated water project when it gifted me this video. My first time on your channel and wow, what a treasure trove of ideas! Subscibed. 👍

[@bhprodbeats]

your projects are serving the whole world and i thank you for that

[@ultrablazed9126]

Id love to see this panel operate during winter on something like a small tent or shed

[@7sevin7]

You've truely an asset to humanity. Thank you so much for traveling back from the future to bring us this technology Weasely Crusher.

[@West_Coast_Ganbaru]

This man is a national treasure

[@cooj9503]

I used to watch this guy as a kid and he always kept me entertained. Glad I came across this page again!

[@robertchristianson1187]

Awesome job. I have built several different types of air heaters and this design blows all of the others away.

[@ComeAlivewithMK]

What a great presentation and I really appreciate how you make it. Logical and simple. I was able to follow and I know nothing about solar energy. Thank you so much.

[@ob_wan]

I have been watching your videos for about a year, (if I remember correctly,) and I have to say - you are one of my favorite youtubers. Your explanations are simple, even for super complex topics, and you make your projects accessible to everyone! Thanks for what you do! (also your birds are really cute lol) -A fellow Michigander

[@namo6504]

Really you are bringing the light mr. night hawk. Thank you for this knowledge of working experimentation

[@XWmo]

The Idea was communicated very plainly , easily and in one flow.

[@tracybowling1156]

Another well thought out and easy to understand episode. I appreciate the thought and time you spent to make a very interesting and fun video for us all to enjoy

[@anhdangduc1061]

As someone who is living in the tropical region, I have been following this series and Tech Ingredients' for quite a while. I hope to see the new video about cooling panels soon since it will definitely help with the upcoming dry/hot season.

[@user-nr4or2fq1k]

Loved your video. Very well done. One suggestion: I believe that the panel's efficiency may benefit from additionally painting the sheet metal BLACK on the side that FACES the heated air. Right now, the shiny metal surface prevents radiation from entering this air cavity. This is called emissivity (and is the opposite of reflectivity). Your panel may then additionally benefit from a shiny surface being added to the insulation-side of this air cavity, which would reflect any radiation back again. To be clear, I am NOT sure that this will increase efficiency, but it may be worth experimenting with these ideas. For example, the radiation may just be absorbed again by the black inside panel and go to the outside. Your experimenting will verify IF these are indeed improvements, or not. Again, very well done.

[@Charlie-Oooooo]

The king of doable DIY projects🤴

[@johnlambert7405]

I am building a house and picked hydronic and radiant heating because I knew my energy nerd juices would appreciate the modularity for tinkering. I may even attempt some radiant cooling (with separate dehumidification) here in balmy Kentucky. Keep these coming because they are great!

[@GuillotinedChemistry]

Another great video! The step-by-step explanations were extremely well done. Can't wait to see what's next!

[@danpetermann6509]

I built a solar heater for my last house, mostly out of scrap wood and R21 board I had laying around. 8'x4'x8" 4 layers of black cloth screen, 1/4" plexi cover, 8" inlet/outlet with a fan. Inlet temps around 58F, outlet at mid day 110F. Heated most of my 1100sq ft house all day by its self.

[@DaveHojo]

I like the idea of dual purpose. The Trombe wall concept as a cooling device seems pretty cool (pun intended) provided you can re-orient it out of sight of thermal radiators.

[@SimpleThingsOnly]

It took me 30 seconds of this video to decide to subscribe to your channel. I didn´t see any of your videos before. Keep up with this brilliant work!

[@JuanVanSteyvoort]

Dear NightHawkInLight : YOU are the brilliant one!.... Thank you so much, for that new video... 🙂 From Brussels, with Love....

[@nobody8717]

Suggestion for holding it together, which is relatively cheap. 2x wooden square "picture frame" made of 1x2's 4-8x 8" bolts and nuts. think of a flower press, or binding press.

[@user-vu6wy1so6o]

This guy is awesome. Such a great presentation. A worthy Nobel Prize Winner.

[@analysisonlight605]

This is a good idea for heating greenhouses in the winter.

[@Parmigiano1]

Nice! Now instead of 30C in my office I can use this for cozy 60C working environment.

[@mrskeleton9462]

i imagine homestead owners would be drooling over this video, Finally something DIY that's both practical and not dangerous!

[@glennscott8622]

This is absolutely timely, thank you for all your efforts. 🙏

[@uneektalent]

Custom make the clamps from 4 inch PVC cut into 2 inch rings. Cut a slit in one side, heat and curl the ends outward to make a round version of the downspout strap.