If you look at this solar generator from [Concept Crafted Creations], you might think it’s somehow familiar. That’s because the design was visually inspired by the James Webb Space Telescope, or JWST. Ultimately, though, it’s purpose is quite different—it’s designed to use mirrors to collect and harness solar energy. It’s not quite there yet, but it’s an interesting exploration of an eye-catching solar thermal generator.
To get that JWST look, the build has 18 mirrors assembled on a 3D printed frame to approximate the shape of a larger parabolic reflector. The mirrors focus all the sunlight such that it winds up heating water passing through an aluminum plate. Each mirror was custom made using laser cut acrylic and mirror film. Each mirror’s position and angle can be adjusted delicately with screws and a nifty sprung setup, which is a whole lot simpler than the mechanism used on the real thing. The whole assembly is on a mount that allows it to track the movement of the sun to gain the most sunlight possible. There’s a giant laser-cut wooden gear on the bottom that allows rotation on a big Lazy Susan bearing, as well as a servo-driven tilting mechanism, with an Arduino using light dependent resistors to optimally aim the device.
It’s a cool-looking set up, but how does it compare with photovoltaics? Not so well. The mirror array was able to deliver around 1 kilowatt of heat into the water passing through the system, heating it to a temperature of approximately 44 C after half an hour. The water was warmed, but not to the point of boiling, and there’s no turbines or anything else hooked up to actually take that heat and turn it into electricity yet. Even if there were, it’s unlikely the system would reach the efficiency of a similarly-sized solar panel array. In any case, so far, the job is half done. As explained in the build video, it could benefit from some better mirrors and some structural improvements to help it survive the elements before it’s ready to make any real juice.
Ultimately, if you need solar power fast, your best bet is to buy a photovoltaic array. Still, solar thermal is a concept that has never quite died out.
We are all preoccupied about AI slop but we accept the “content creator slop”. This is an article about something that doesn’t work, that it’s only purpose is to get views and supposedly teach you something but at the end it only waste your time. It gets water to 44ºC, one time I got to 41ºC with a fever and I am not even solar powered!. Youtube is full of sloppy made inventions by big views creators that are not more than entertainment. What’s the catch of this one? 3D printed suports and adjustable screws? It’s a freaking parabola, if you do the maths well first you don’t need any adjustments later. A lot of those videos only have bad prototypes after bad prototypes because the only thing that matters is making a video and getting views. It’s like seeing someone try to reinvent the car starting with a triangular wheel and sayin “oups haha this one didn’t work uh? Click and suscribe! Gonna try a square one on the next video! “.
I usually ignore posts that complain about youtube videos, but you make such a compelling argument that I’ll just skip this one. Thank you for saving me from wasting some time.
I wish I had do ne the same. When he said he was comparing gold & silver because the former reflects infrared better, was like… ok… but they when he used “gold” & “silver” paint, I’m like …what?!? Then he forms teach panel using a spherical mould, discovers his error, explains spherical vs parabolic, then proceeds to use a single mould again. He doesn’t even understand high-school geometry.
Oy. 10 minutes I won’t get back.
Glad I merely skipped through it. Once I saw the spray paint I knew this was going to be a whole big “content” charade.
Didn’t even bother to see if he found out that the hexagons aren’t so you can make all segments the same. They’re all off-axis parabolic mirrors. 6-fold symmetry, so there’d be at least 3 different mold shapes.
I feel this comment. I’ve seen quite a few like this, one that come to mind at the moment made multiple videos in a row where they got highly liked/upvoted comments with very good and implementable suggestions that they ignored completely just to implement a poorly thought out ‘improvement’ in the next.
Thank you for doing such a good job expressing the sentiment that many of us feel.
I’ve got no problem with people getting a lot of money making vacuous content on the internet.
I DO have a problem when said vacuous content is then passed on as useful/helpful/informative.
Bummer to see so much of it in places that should have higher standards, but I guess it drives traffic – as usual this benefits everyone but us little guys who just want to learn something.
Why not use an old satellite dish?
A round dish is not really optimal because you have to keep pointing it at the sun. There’s a better version that uses a half-pipe mirror pointed at a black pipe with water or oil running through it. If you set it up at a suitable angle, it tracks the sun automatically across the sky.
I’m not an expert but doesn’t the sun’s position change throughout the year? Surely a tracking array that ensured every mirror is focused on the same point is more efficient? To self adjust for the seasons as well as time would t it have to be a huge array. I believe even the salt battery types in Spain and Nevada have arrays that move with the sun? I would love. To know how a stationary version could work as it would perhaps be more reliable and require slightly less maintenance.
You accept some ‘slop’ in the design.. but it’s a parabolic ‘half-pipe’.
You no longer need to aim one of the axis due to the linear shape.. most of the light will still bounce back and hit the target, although ‘some’ light may miss at the ends of the fixture.
The shape/size of the pipe will dictate whether or not you need to adjust the ‘other axis’. It’s ok if the morning/evening sun converge on the upper edge of the pipe if the noon sun converges on the lower edge of the pipe.
Take a look at a ‘Parabolic Hotdog Solar Cooker’ .. replace hot-dog with a pipe and working fluid.
It’s ok if the morning/evening sun converge on the upper edge of the pipe if the noon sun converges on the lower edge of the pipe.
Uh, no. Think about it. The location on the pipe changes seasonally
You’d think so, but the constant adjustment requires a constant supply of power to your motors and computers and whatnot. With small systems like this, you can easily spend 10-20% of the daily output on the tracking unless you put some real thought and money into optimizing it.
Meanwhile, a mirrored half-pipe just needs you to nudge it to a different angle about once a a month.
Could be a nice pool heater unit, doubling as a sculpture as well!
I’ve seen an old web page that did exactly that, with much better results. They did have to manually cut lots of mirrors.
Waiting for someone to comment about the superiority of a polar mount vs. az-el mount.
An equatorial mount would be superior to either :-)
It seems the main difference between a polar and equatorial mount is that the declination is typically just adjusted once for the polar (because you’re usually aiming at geostationary satellites over the equator), while it’s motorized for the equatorial (so you can aim anywhere). It would seem like just adding a servo to a polar mount would make it equatorial, assuming it had the desired range of motion.
About that projector on the tabletop… That’s a neat use for it, if you make videos.
I have a couple of projectors laying fallow, and thought about projecting onto my work table, inspired by interactive art exhibits. But Art is a poor use of precious workspace, and I don’t do videos for mass consumption. So other than projecting sewing patterns on my work table, I can’t think of what to use a projector there for.
Does anybody else project onto a work table? What do you use it for?
On a slight side note, a projector could be an interesting way to get a mirror array aligned. Trying to use the sun to align the mirrors could be tricky, especially with that many mirrors, the weather can get in the way and the earth keeps moving. With a projector, you get a fixed and [more or less] perpendicular light source.
if the projector is located [more or less] infinitely far away, that is.
My workshop ceiling isn’t that tall.
A Stirling motor at the focal point will probably be a more effective producer of mechanical power than a heater, water circuit, and gas turbine.
If you integrate an alternator with the Stirling, now you have electric power.
Enclose the engine (and the alternator, if you wish, to avoid the need for shaft seals) and then pressurize the cavity with nitrogen, engine efficiency goes up.
that would be cool if someone create an actual telescope out of this
Lots of complaints about the usefulness of this but 44C is warm enough for household hot water… my heater is set at 49C. Just take an old water heater that no longer works, bury it in the ground for some insulation and run that water back/forth to the heater until it reaches some set point and you’ve got 40-80 gallons of hot water relatively cheaply.
44 C is a perfect temperature for getting yourself ill from legionnaire’s disease
https://www.energyvanguard.com/attachment/legionella-growth-water-temperature/
Average ground temperature below 3 feet of soil is between 8°C and 21°C. Burying the tank in the ground will most likely suck heat out of the tank. On the other hand soil temperature consistancy is why ground source heat pumps are so much more efficient than air source ones.
It looks cool, but it doesn’t sound like it works any better than a garden hose left in the sun. I took the inspiration from a garden hose left in the sun to build a hot water heater panel on my roof that does raise water to above boiling using just an insulated box, a pane of glass, and a sinusoidal pattern of copper pipe soldered to galvanized roofing I’d painted black. See here:
http://www.asecular.com/projects/homebrewsolar.php
Do you really think this has poor efficiency? Really think a photovoltaic array would harvest more power than this?
I didn’t get the actual size of the mirrors, but they look like 30 cm wide. The whole array is ca. 1.5 m in diameter, so about 1.77 m^2 area. It will intercept close to 1.7 kW of total power, and delivered about half that to the water load, around 50% efficient.
Not horrible. And loads better than the 20% you’ll get from a photovoltaic panel, if all you want is raw low-grade thermal power.
There are lots of other things to take issue with here, but efficiency wouldn’t be high on the list.
You’re right. It depends on the end goal. If it’s just about heating water, great. If this is intended to then generate electricity… eh.
So how inefficient are his mirrors that he’s barely getting above ambient temperature? It isnt really worth doing any math here, but it seem like this thing is only somewhat worse than using the secondary focusing mirror on its own.
I started working on something like this years ago with the plan to use spin-cast aluminum mirror segments set up for their particular arc segment in the arrangement. These would then be finished, polished, and coated.
Could never get the spinning rig balanced quite right though – 1/2hp motor w/ belt drive to a 4wd silverado cvt shaft/front wheel bearing and brake rotor assembly that the mold plate/box would “sit n spin” on.
Theory says curvature control via rpm, arc segment control by offsetting from center – never quite got that far though.
It IS worth doing the math: As Akin says; “Engineering is done with numbers. Analysis without numbers is just opinion.” Do the arithmetic: You’ll find the efficiency is not bad.
Everybody is harping on the fact that it only reached 44 degrees, and completely missing the point that it’s heating 20 liters of water to that temperature.
Would you be more impressed if it got a liter of water up to boiling in ten minutes instead? That’s about the same energy input.
Interesting group psychology at work here.
Bah. For the pedants: … same power input.
Yep, just goes to show that even with this crowd you need to show the “right” results.
Thanks for the analysis.
This thermal solar power harvester must be poorly made to be less efficient than photovoltaic pannel to boil water…