Solar Hot Water: Boiling Diodes test! Solar electric cooking research

UPDATE: this works - check my other videos linked below! Solid state "Semiconductor" solar-electric heating elements are potentially very useful for solar electric cooking, solar hot water and solar heating. They can cook food, heat water and produce space heat directly off of solar panels. The main benefit is they can extract MORE heat (watt-hours) from the same solar panels versus resistance heating elements (this is explained and demonstrated in my other videos linked below).
First vMP Diode Chain Bench Test! • Solar Electric Heating...
Another bench test with diodes: • Solar Heating - Solid ...
14 WATTS boils an egg! Solar Diode Cooker: • Ultra efficient solar ...
University Research PAPER on Diode Chains/Strings:
• Solar Powered HOT Diod...
This video contains a few clips from my solar workshop where I am investigating the potential of solid state heating elements for solar cooking and heating applications.
This video is part of a series investigating Solar Electric Heating with Solid State semiconductor heating elements. Diode strings are a very efficient way to get the most electric heat possible out of a PV solar panel array, and I became very interested in applying this technology.
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Part 1 of series - first heating element tests: • Solar Heating - Solid ...
This video (solar hot water test)
Part 2 explaining how solar powered solid state heating elements work:
• Solar Electric Heating...
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It's hard to believe, but simple diode strings (diode chains), which are semiconductor junctions and some of the most basic electronic components available, can actually hold the Voltage of Maximum Power (Vmp) of a solar panel array nearly all day. And they can do this without any supporting electronics. They are a practical heating element for solar electric heating and PV-to-Load applications.
PV-to-load is the concept of attaching useful loads directly to PV solar panel arrays (direct solar electric DC power), bypassing the traditional battery, inverter and charge controller setup. Operating heating loads directly off of solar panels makes sense as it saves wear and tear on expensive discrete solar power components and equipment. See videos below for more information about this concept.
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🟢 Other videos
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🟢 Solar Heating and Cooking Playlist - PV-to-Load
• Solar PV To Load Heati...
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🟢 Solar Electric Heating Playlist
• Solar PV Electric Heat...
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Solar Electric Cooking Playlist
• Solar Cooking Videos
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🟢 Solar shed ventilation with DC fans and Solar Panels
• Solar Shed Ventilation...
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🟢 Background info on My Solar Workshop (metal building)
• My Solar Workshop - of...
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Check out our blog - Solar Thoughts Blog!
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Music credits: by TuneTank, Pixabay

[@solarpoweredge]

This technology is widely misunderstood. To overlook or dismiss diodes strings would be a mistake. I recommend watching my newest video to help understand the technology: kzbin.info/www/bejne/amO7epV-dp53rJI Here is a short explanation. Diodes are the _simplest_ way to extract the maximum (heat) energy from a solar panel that has ever been found - so far. It appears only a few researchers have investigated the idea. Diodes are NOT Ohmic. Relationship between current and voltage is logarithmic/exponential depending on which way you consider it. They drop a set amount of voltage, which is "relatively" constant. As a result, they function beautifully as a direct solar power heating element, providing "MPPT-like" behavior. The problem is this is relatively obscure technology, few understand its amazing simplicity, and there are no really suitable diode packages at this time. So far, all researchers have had to make do with what they could find off the shelf. Usually axial packaged diodes... So far I have built 2 solar cookers and working on a water heater using this technology. I hope to scale these projects up later.

[@tobysmith3668]

If you place a low value resistor under the diode string; and run that through a TMOS power FET to ground; you can control the current by PWM (pulse width modulation) and save the diodes from over-current failure.

[@solarpoweredge]

Another good idea to experiment with, thanks!

[@tobysmith3668]

@@solarpoweredge An Arduino will monitor the resistor voltage, and drive the TMOS power FET directly. This will allow you to set the maximum current,

[@solarpoweredge]

@tobysmith3668 I bought an arduino board a couple years ago, hope to dust it off soon and give it a try :)

[@tobysmith3668]

@@solarpoweredge It will work best if the sending resistor actually ties to ground on one side, with the FET just above that. Some have a differential voltage amp, but grounding one side will cut a lot of noise without hurting gate drive levels. Mart Hale in Florida is a long time friend, and sent me you contact information. We were thrown off of FB about the same time, but we had exchanged emails first.

[@ddouglas3687]

👍 Great stuff!

[@solarpoweredge]

Thank you :D

[@solarpoweredge]

Note this is NOT electrolysis.. test was conducted with pure distilled water.

[@oscaranderson1822]

Love your work I hope you don't mind me trying a few things at home. I Am The lone ranger of home maintenance and repair. I feel a solar-powered heat system coming on

[@solarpoweredge]

Glad you like this stuff :) no worries, "trying stuff" is the core of DIY, have at it. A solar powered heat system sounds like a good plan :D

[@timbrown9305]

Have you done a cost base for diodes vs. resistance cost of element watt for watt ignoring efficiency?

[@solarpoweredge]

Sure, comparing diode strings to ceramic PTC, nichrome/kanathal, carbon paints etc. there are all sorts of ways to make heat with slightly different cost/benefit ratios. Diodes stack up fine. They cost just pennies, unless one wants to buy huge power diodes. I am building larger heaters using power rectifier diodes that are still affordable. Engineering new solutions requires taking all pros vs. cons into account. Cost is certainly not a roadblock with diodes. Diode junctions are a few cents each, and can harvest more watt-hours over varying conditions without complex circuits. They can last for years if "not overheated". If we added an MPPT circuit to resistance heating elements, the cost would increase, but such a solution could still be useful and harvest more watt hours. Diodes behave similar to MPPT, harvesting more power but with vastly reduced cost and complexity. So they are close in benefit to MPPT circuits, yet very close to simple resistance elements in cost. Even in their construction and layout, they're not too far off. One group of researchers used strings of tiny little diodes for many months boiling water and cooking food, and they survived. They did their home work.... the amount of extra heat (or watt-hours) collected over the life of the system is meaningful and significant. Diode heaters are an obscure topic currently. But there was a time solar panels were 1% efficient and pretty obscure as well. There was a time when no one imagined painting a heater on their wall with carbon paint. But progress moves forward as new technology becomes further developed and slowly emerges out of obscurity. If direct PV-DC powered systems become more common in general, I believe direct PV DC diode heaters will play a role as well. Practical application: leveraging the advantages of diodes strings, I have built multiple diode based cookers that work even in cloudy weather without collapsing the PV voltage under poor conditions - thus harvesting more heat without using complex electronics. Here's one that made it to video: kzbin.info/www/bejne/eYPLnI2ma6p2fs0

[@priestesslucy]

​@@solarpoweredge thoughts on using these as the heat source for a refrigerant cycle?

[@solarpoweredge]

@priestesslucy3299 Hi, that's really thinking outside the box! if you wanted use a solar panel to generate heat for a refrigerant cycle, it would be a great opportunity to use diodes. Rather than use a complex MPPT DC-DC circuit connected to a nichrome heating element, a simple string of diodes could do a better job and cost less. There would need to be some sort of heat sinking contact between the refrigerant and diodes, but there are lots of ways to accomplish that. Another challenge is matching the diode string to the solar panel input, as some solar panels might have a slightly different max power voltage. But it could definitely work!

[@petevenuti7355]

How could this be more efficient than resistive heating? Is it not the resistance where the heat is coming from?

[@solarpoweredge]

@petevenuti7355 Hi, diodes are not resistive (ohmic). This video is a short test earlier in my research. *My other videos thoroughly explain it (see below). There are also scientific papers on the subject. kzbin.info/www/bejne/amO7epV-dp53rJI kzbin.info/www/bejne/eYPLnI2ma6p2fs0 kzbin.info/www/bejne/bHWTkoijoLqEibM kzbin.info/www/bejne/rZmyiXiCoNGrh5Y

[@JimmyCall]

An application would be to store heat for night use.

[@solarpoweredge]

@JimmyCall That would work - also many people have suggested a diode immersion heating element built inside a metal tube. It has been more difficult, but I am working on it