Thanks for posting. In 1970, I build one of these for a science fair project. I elevated the storage tank (a 5 gallon metal can) and used thermal convection to circulate the water. Worked great and was a great demonstration of solar water heating on a budget. The whole device cost less than $20 to build and was a fun project.
For some reason I had a problem getting mine to circulate by convection. Once the water boiled it caused pressure in both directions within the pipe and would just repeat with no circulation
@@drd1924 The tank has to be elevated above the top of the collector. The water should never boil. The size of the hot and cold pipes to the collector should also be of sufficient girth to allow unrestricted flow between the storage tank and the collector. I won the 6th grade science fair with mine. I was 12 years old then. Enjoyed the heck out of building it. I still have the collector that I built in 1970!
@@winfordnettles3292 Gotcha, thank you sir....Perhaps my pipe size was too small to allow sufficient flow for exchange...Will try again. I was also thinking of installing a check valve to ensure proper flow direction should boiling occur
In Australia, 80's. There was a same system unit called 'Suntrac'. Had 2 reflectors, about 5ft long, 2-3 ft wide. Tank on the top, clear covers, and a water pressure tracking system. The centre pipe was sealed with a gas inside, this pulsed the heat into a sealed end bulb within the tank. Worked well.
Back in the early 80's I worked for a company who installed this type of hot water system in Nevada. Pre built 8" long parabolic collectors with blackened copper pipe set into an aluminum framework on the roof of the house. the system had a sun tracking feature that kept the collectors facing in the optimum direction while set at the best average angle to the sun for the latitude. This was a closed loop system. Meaning no household water entered the system. The system water was pumped through a heat exchanger tank and back up into the collectors. The house hold water passed through the heat exchanger into a storage tank and then into the existing hot water heater and into the house. This method allowed the existing system to be isolated in case of emergency. On many occasion during initial start up I watched thermometers go from ambient air temps of 50 degrees F to over 250 degrees F as fast as the needle could move. As the system would run this temp would come down to a more reasonable 200 degrees f. The normal operating temp of the system was designed to keep the household water in the 105 to 115 degree range. This technology should and needs to be utilized more these days.
@@drd1924 The tracking feature was simplicity at it's best. There was a photovoltaic eye that had a small riser held above it essentially dividing the eye in two. as the sun moved (earth rotated?) and exposed the eye to sunlight a small motor connected to a chain drive would activate moving the collector just slightly to re-shade the eye and stop the motor. The riser was flat on the bottom and half circle on the top this allowed the eye to catch the correct amount of sunlight throughout the year without adjusting it.
@@NVOutsider Very creative!, Thanks for the explanation I figured it had to utilize some sort of CDS cell, whats puzzling me is... Did it know to reverse directions in the morning to start over or did it have to be reset every day?
@@drd1924 the riser piece was 1/16" to 1/8" thick painted white aluminum. It sat directly over the center of the eye. so when the sun set the collectors stayed facing west as the sun hit the eye in the am everything would rotate to the east and start the process over. I have a feeling my explanation is really dumbing it down due to my 18 yo lack of understanding and it being about 40 years ago. The system was manufactured in Arizona by a company called USMC (?) What is a "CDS" cell?
@@NVOutsider Hi, A CDS Cell is short for Cadmium Sulphide (a light controlled variable resistor, The Photoeye) Thanks again for further explaining, rotating would make more sense. I was picturing the mechanism Panning and could only think of using limit switches to stop the movement and reset it. But simply rotating would simplify it even further...Very Cool
In the '80s........I had a house with two four by eight solar panels in Massachusetts......... With one sonny day it gave me 160 gallons of hot water..... Heat exchanger, recirculation pump, anti-freeze.........it was all a great idea and savings..........this system looks to be more compact, and more efficient. Thanks for sharing.
Thank you for taking the time to put this together. While there are lots of interesting comments, know that I found you while looking for examples of how to heat just over a cup of water to use in my Aeropress. I don't need a capacity of more than one cup, so this solution is among the tops. We're soon to be full time RVers, and want to figure out unique ways to conserve LP/electric. Thanks again! :)
I though about this concept a few years back. I can see that it works! What I was also thinking was, since I live in a tropical country we have great exposure to the soon through the year, so I was thinking that it might be possible to reach boiling point with a little bit more industrialize set up in order to be able to get salty water from the sea and take the salt out! It could be inefficient but the sun is free so...
a donut ring of seawater, the vapor dripping from an upside down cone in the donut hole to the freshwater container underneath, the tide refilling the seawater part, solar power to provide electricity to pump the fresh water up to a roof tank
1) Build parabolic mirror similar to the size in this video. 2) Install a clear glass oven pan with sea water in the pan. 3) The sea water will evaporate and rise as steam. 4) That steam is pure water. 5) Instal a thin sheet of clear acrylic a few inches above the pan. But angle the acrylic so that the steam droplets which gather on the àcrylic will slide down the surface of the acrylic and fall off into a separate pan. Voila! Clean water.
A good solar still easily reaches 50°C under sunlight and offers pure, hot water. An autonomous, off-grid user doesn't need those expensive solar hot water panels. Just a plastic sheet and a pump is enough :-) .
FYI, that type of Pyrex measuring cup is made from soda lime glass. Rapid temperature changes, such as pouring boiling water into it, can lead to violent shattering of the glass. Cool demonstration though! Thanks for sharing.
Use a horizontal arc that way it always point at the sun, the double curve is harder to make but doable with a flexible material, or just section and angle the sections to follow. This obviates the need for tracking. Also paint the pipe with flat black high temp. engine paint, so you get more frequencies absorbed.
I wonder if we could use the system to heat a working fluid so it could expand and push a hydraulic piston to follow the sun? My idea was to use the heat from solar panels to automate their turning.
I built one of these for a science fair project in the late 1970's. I painted the copper pipe black, which made it heat up a lot faster than the bare copper.
Mount this below a water tank, then allow convective circulation to heat the water in the tank by day, then by night, the heated water will stay elevated in the tank. Likewise, make another radiator, but mount it above a second tank, to cool the water by night with convective circulation, then by day, the cool water will stay low in the water tank. This way, you have both hot and cold water available.
I am really grateful for your precious time, used in this demonstration video of this simple and at the same time so fundamental and important for the development and improvement in our homes, not to mention the economy with the consumption of electric energy, and not to mention that the steam of water can also be used to generate mechanical and electrical work, through a hot air engine using a coil for example. congratulations and thank you very much. big hug my brother
Well not with the prices going tenfold in a few months this will become very very relevant. Thank you for your great video. I have about 16 months to master how to use alternatives for heating our house. I found already some very usefull stuff.
Thanks for sharing practical scalable DIY tech that anyone who's sat in a car on an overcast winters day could understand the principal being demonstrated. Thanks nice modular system.👍😊
Very informative video. It is great that the use of copper is limited to one central pipe vs a long copper coil or multiple parallel copper pipe collector as copper is expensive. While glass mirrors would reflect more solar energy mirror polished stainless steel sheet metal would likely be more cost effective. Solar concentration is a great technology but it does have some drawbacks to be usable for the lay consumer. Boiling in a water heating system is not ideal as pressure builds up and could cause bursting issues. There would have to be some type of circulator, heavily insulated HW storage tank, temperature monitoring device, and a device that will shut off the circulator when approaching the boiling point of water as well as to rotate the collectors out of the sun. Also having to manually adjust the angle of the unit every few days is not feasible there would have to be some type of mechanical unit to pivot the collectors.
This is great! I wonder how much difference it would make to paint the pipe a flat black, just a thin coat, maybe with BBQ or exhaust system paint, or if oxidized copper is sufficient?
I could be misremembering my college physics, but it's not a coincidence that it stopped at the boiling point of water. It stopped there because the water was boiling. Liquid water can't get hotter than the boiling point. All the energy going into the pipe was going into producing water vapor. After all the water boiled off, the pipe would start getting hotter. It might have melted the copper eventually. It would be interesting to know how big a reflector you'd need to heat a water heater full of water from say 70 F to 160 F over the course of a day.
If you install one way check valves the heat of the water will propel the water through the pipes/hose on a continuous flow. And I agree painting the copper pipe black will increase it's effectiveness and will draw the water from a tank or vessel and pump it into another tank or vessel.
This can heat fluid to circulate in hydronic heat system, too…putting 1-way check valves moves the hot water in the direction wanted, so it can recirculate. Can also use thermostat to control it. Needs an expansion tank also. But it’s a fairly low-tech system that can work even in winter, as long as there’s enuf size to system, & cloud reflectance. A backup small tank water heater can also be in the loop, for dim days & nites.
my Grumman Sun Stream solar water installed in 1978 COOKE water for thirty years before the A O Smith stainless steel tank began leaking. The optimal tilt is 37° , I had 45° in my location. on Dec 21 , a partly dsy, the late afternoon tank temp was 97°. 80 gallons of warm water when the incoming temp was 52°. Cost with tax credit: 1695.00 Install labor 350 antifreeze replace 300 total cost $2445 reduction in electric bill was over 200 kwhr per month 200 kwhr yearly or $240.00 per year electric cost 80,000 lbs of pollution ! A hybrid water heater cost $1395.00 and will reduce electric bill almost as much as the solar water heater.
Imagine a connecting the bottom to a small plex hose that goes to a small cup reservoir elevated to the just below the top of the solar exposed pipe when elevated as in the video. As water evaporates/boils away at the top, new cold water is gravity fed into the bottom from the reservoir. Helping keep water throughout the solar exposed pipe for maximum heat transfer. Then one can use the steam given off at the top to cook food in an insulated steam box.
All these solar panels sitting on top of homes have lots of heat. All that heat reduces the panels life and efficiency. They need to be sealed then water induced. Thus providing free electricity & hot water without depleting your electric reserve. I've done it on a small panel. Used a parabolic dish to focus the sun on the panel. Then ran water through it. Resulting in tripple the electric output~!
The technic is called "solar collector" and is much more effective to heat up water directly as solar cells - where the flat collector have lower efficiency than tube collectors, even at low outside temperatures.
Would like to have seen if that device could heat running water THROUGH it, to actually know if it is feasible to install into an off-grid water system! Putting a half cup of water into ANY metal container, out in the sun, even without a parabolic refractor, would still heat the liquid!
This reminds me a lot of the solar air heater. It looks good with static air. But once you start cycling air through them, you find they have a very low capacity to heat a volume of air. I suspect the same is true with your solar water heaters.
Would blackening the pipe add efficiency ? Could you make a return pipe e.g. behind the mirror and a reservoir on top using thermal circulation to heat a larger volume ?
I am assuming that you would need a water expansion system for the hot water. Also, I would use a glycol of some sort instead of water to prevent freezing in winter. How about a large insulated heat sink to preserve the heat. Have the tubing to the house run through the sink to absorb the heat and distribute either to the domestic hot water or some form of radiator set up. I'm looking at our mountain house and trying to keep the energy bills low enough so that I don't have to sell it with the prices of power these days.
Obviously, in order to be anything other than a novelty, the hot water would have to somehow be continuously pumped, as heated, into some sort of a reservoir tank. Then, when full, the system would have to know how to stop heating unless one wants an explosion. "Little" question, like that, make the difference.
Just a suggestion, wouldn't it be better to have the reflector support on the outside? Because when there's those wooden things inside, the shade from each would decrease the overall temperature as sun rotates? I'm about to build something similar for steam engine.
Question..... do you have any data on a max temp at a constant flow of, I’ll shoot low, 1 GPM? Standing water isn’t a usable resource. I understand this is a demonstration but it looks to me as if it’s being manipulated by showing this unit in a static situation. I would love to see a full scale unit in operation with the heated water being used. I guess I could make a cup of tea with this in an emergency.
This can be implemented across regions where there is no access to electricity, I hope social conscious young men like you can provide this system at minimum cost or for free to people in need. Thank you for your interest.
I think i came up with a one way heat diode. My idea is that id have a few energy collectors and a heat battery. Have them dump the excess heat into the battery. Otherwise it would just heat up a water heater. Or it would heat up a air dryer. I have an idea for a filtration system that uses water instead of expensive filters. I haven’t figured it out yet but ive seen the system used in paint booths. I just need to dry the air after it comes out or it would grow bacteria eventually. Also we can use our waste stack as a heat dump. I was thinking we use our sewer as a geothermal heat dump. So the first goal is to generate an excess of heat. That way i have enough of a heat differential to generate energy. Once the heat battery is hot enough for steam its a wrap free power from nature with just maintenance or what ill do is select materials that need almost no maintenance. Actually im thinking of making a open source youtube series on what i think the perfect house would be. With some help i believe instead of a net zero house we can make a -100% house. With it capable of absorbing and holding nearly every pollutant humans make and turning it into a clean energy. With the filtration system i mentioned we would be cleaning the air we take in from the outside of road dust and other fine dust pollutants. We would have a cooling effect on the ground similar to the shade a natural forest would have. (Thermal pollution a theory i came up with in 2010.) and most importantly and obviously provide energy instead of take energy.
Interesting if you need really hot water. However it cannot collect any more heat than what is collected by the size of the reflector. If you simply had black pipes covering the same area, the heat collected would be the same?
Thanks for an inspirational video. I nearly got it correct, I have the parabola built. I have not yet put the copper pipe in. All my experiments to date have not worked for a couple of reasons: 1/ no copper pipe (WHAT I have to have a pipe at the apex of the parabola?) (Answer: DUH!) 2/ not a shiny surface. (Unsure what material I used, I think is stainless steel) All that said, my construction is very similar to your, except I do not have a center support, but it is very ridgid. Loved the safety comments, like don't pick it up by the pipe, err sorta been there done that. (think, wet paint DO NOT TOUCH) Thanks mate
I understand not going to the extra trouble to enclose the pipe or glaze the entire apparatus. What I don't understand is why you didn't bother to paint it black, which would have been very simple, and would have increased temps significantly.
It's not boiling, because you're only measuring the hottest part of the water, which will float to the top of the pipe. In order to get it boiling, all of the water needs to reach about 99 °C. But if that would happen, most of the water will just shoot out of the pipe. Just like when boiling water in a testtube. Nice idea though. If you know the exact amount of water and the temperature rise over time (you need to empty the water into a cup for this, to get precise readings of the temperature), you can calculate the heating power.
On another day when I was not shooting video, and there was no wind cooling the pipe by blowing over it, the water did reach boiling, I could hear it bubbling in the pipe, and see a few drops of water splashing out the top.
Why isn't it used broadly? Because it works only in summer - that's 1/3 of the year. And you need your own roof for the installation, which means you can't have it if you live in an apartment.
While black paint does absorb heat, I suspect that the reason it did not help is that copper is such a good conductor of heat, that the heat absorbed is carried inward (toward a cooler part of the pipe), and transferred to the water. As long as the outer surface of the pipe is hotter than the inner surface, the heat will flow inward.
Also, while black is the best color for absorbing heat, it is also the best at radiating it. So unless it radiates all of it IN, toward the pipe, the effect would indeed be negligible.
Only works in hot sunny conditions though. I think evacuated tubes are a much better solution. You can buy the tubes now and build your own heat exchanger. Think your idea is nice though for hot water but in hot countries only.
Here's another tip - try using a candle flame to coat the copper pipe with soot to increase absorption. Over 20 years ago, I made a dish collector from a 1.2 meter diameter satellite dish coating with aluminum foil and later a mylar survival blanket which could be focussed using air pressure. After coating the bottom of a small pan with soot, it was able to make a cup of tea in about 2 minutes! If I had the capability then, I would have made a hollow carbon-blacked copper sphere to collect all the energy without any reflections, or make a hollow sphere out of thin copper tube. For a trough setup, a crescent-shaped pipe formed to capture reflections might be worth experimenting with!
How much water you producing with that little thing? When the power is off I have laid black garden hose in the yard and fill it with water and let it stand for a bit. Gets pretty hot. Won’t boil but hotter that you can stand.
I am going to try this to heat my water supply with this unit. Do you have any recommendations from yourself or RU-vid videos you think are worth looking at and executing on that information Sir ??? Thanks
it will operate at peak efficiency during the middle of the day. the early morning and late afternoon will only be at 1 tenth of the solar exposure during the middle of the day
You are correct but if you position the reflector to catch the suns rays at the maximum point of the day, the remainder each side of maximum will be a ramp up to maximum then a tailing off to minimum. During the cycle of the day with a good sized system this will be more than enough to give a days hot water for a domestic system in a sunny climate. There are many systems of this type on roofs in Spain. The rate either side of peak efficiency is not 1 tenth of the exposure, as the sun travels across the horizon the efficiency increases to maximum (peak) then slowly tails off. This can be improved some with a tracking device that moves the assembly into the peak throughout the day.
Wondering what you would recommend as a simple insulated hot water storage item that is only about 5 -7 gallons? Lots of off grid van dwellers or bushcraft folks could use this sort of heater and store water to cover a 12 hour period. 24 hours would be even better. They could mix cool water with the hot water to use for many applications.
If the whole point is to show how effective concentrating sunlight is, why wouldn't you test it along side a copper pipe without the reflector? Based on what we see in the demo, for all we know a plain copper pipe would have gotten just as hot in the sun.
Have you seen pictures of mountaint skiiers sunbathing with just swimsuits on the top of the mountains while air temperature is minus? Or just look stand behind the window on sunny days. For Canada is large - efficiency depends on latitude and time of year. But concentrated sun is powerfull.
just doing some really rough calculations it looks like you're getting 150btu/hr out of this example. Pretty cool for such a simple and small design. my math: 6 secs to rise 1 deg = 10 deg/min = 600 deg/hr 600 deg/hr = 600 btu/hr per pound of water 1/2 cup of water = .26lbs of water 600 *.26 = 156 156 btu/hr
Great video. I too am interested to understand whether concentrating solar energy in this way can be used to heat the air in an enclosed cabinet that can then be pumped to cold indoor areas.
Excellent sir! By the way: Newtonian laws of force and motion when applied to the angular velocity of a rotating spherical body, when crossed by an implied gravitational force that pulls toward the center mass of the body produces a force vector graph that shows angular velocity at a 90* right angle to gravity unopposed at the poles that changes incrementally at each latitude from 90* unopposed to directly opposed at the equator of the spherical body. The only place where both forces could find balance. Newtonian laws of force and motion predict that if Earth were a spinning sphere with gravity pulling towards its center of mass all unrestricted water on its surface would necessarily have to follow the vector angles produced to the equator and then upward to the point where gravity's fixed and angular velocities increasing forces were equal, but since angular velocity increases with radius it will overtake gravity at some point and propel the water out in a disk and off of th
100ml (half of a cup) 1 degree F each 6 seconds - so around 1 degree C every 10-11 seconds gives me roughly 1 kcal each 2 minutes for 2 sq feet. Its 80W (4,19J/s is one cal/s if i remember correctly) Albedo of the sun in troposfere i think is around 800W/ m^2 soo... roughly computing 150W / 2 ft^2 so 50% of efficiency is quite a good achievement :)
Just happened to watch this your project. Why don't you give dimensions and measurements of parabola, pipe, etc. It would help and make easier for DIYers and help to impoeve and may be get higher temperatures.
Black plastic water pipe formed into a spiral and attached to a sheet of plywood does a better job with less work. 100 ft. of 1" pipe will hold 5 gallons of water.
Thank you for a good video. Can you show how to use this in a thermosyphon? (sp?). If you can heat a drum of water with this, I can see possibly heating a house with it.
You commented a long time ago. I've thought about a heat sink of some sort and then draw domestic water from it as it circulates through. I'm seeing some channels showing this method and it's working for the homeowners. My issue is that a lot of them like this channel do not reply to comments which becomes frustrating. Have you tried the set up or did you put it on hold?
Don't you think by painting the copper tube black, you could extract greater energy from the sunlight in a shorter period of time? How long must one wait to warm up enough water for a ten-minute "hot shower?" I suppose you would inform your audience in the future videos. There is no doubt that it is an efficient way to heat water when it is not overcast. Even when it is overcast there might be a small heat gain.
