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Using the Solar-cooker day and night (without sun?),
producing potable water.
The Metamorphosis,
a device to improve the benefit of a box-type Solar-Cooke


en Espagnol?

Solar Cooker

My Solar-Cooker with 4 mirrors

Mr. Karlheinz Bhm made the experience in Ethiopia that people don’t want to have the Solar-Cooker because he seems to be a primitive and too simple device. And the problem is often, the food must be ready at a special time, even if the sun is not shining. On the other side too many people especially children die by diseases caused by a poor quality of the water. About 1.6 Million people die every year by contaminated water.
These points have been the impulse for developing a small electronic device called Metamorphosis to make the Solar Cooker more attractive.

Here Downloads and Links

Here a Compact Version of the Solar-Cooker Controller

Producing potable Water: Many solar-cooker exist already world-wide to prepare meals. Such a solar-cooker can also be used very well in order to clean water simultaneously. That starts with temperatures from 65 degrees on, this temperature however must be hold for a certain time. Louis Pasteur already recognized that through heating water to a certain temperature and time kills dangerous bacteria, viruses, amoebae and worm-eggs. Through a bacteriological test we achieved excellent results by cleaning water with the Metamorphosis (Approch-Tech Laboratory in Wrzburg). .

Using the Solar-Cooker without sun: What happens if there is no sun for the Solar-Cooker? You can not tell the husband that the food is cold because there was no sun.With this device you can cook in the Solar-Cooker even at night!! You only have to connect a cheap immersion-heater, the rest is managed by the Metamorphosis. The Solar-Cooker is a wonderful isolated Cooking-box and you can prepare food with few electrical energy.

Theft-protection: Often it happens that the Solar-cooker and the Solar-panels are stolen. As a new feature, there is a multiple theft-protection integrated now. There is a alarm if the box is removed.  One more (optional) Alarm comes if the lid is opened. And if you have Solar-panels connected there is a Alarm if they are touched or removed. In all cases you have a loud acoustic alarm and optional a telephone-call.

  • More Features:
    Producing of potable Water according to the Pasteurizing-effect. By the exact controlling of the Temperature and the Time, the water is not heated unnecessary. This has positive effects on the taste of the Water and the Performance of the Cooker
  • Producing of hot water for a given time and temperature (for example for coffee or tea).
    Simultaneous producing of potable or hot water during preparing of the meal, because the empty-area of the solar-cooker is used for it
  • no high Water-tank is required! We use a small and cheap water-pump from a car and the heated water will be available through a small hose directly where it is required, for example in the kitchen
  • Display of the Temperature in the cooker (for preparing the food) and the Water-temperature, display of the Cooking-time
  • High efficient cooking and clean water-production with the box also at cloudy-days or night by using a simple Immersion.- or Plate-heater in the solar-cooker. The cooker is excellent isolated, so you need few energy. Very simple installation!
  • You can say exactly  when the food should be ready and how long it should be cooked. If there was not enough sun the Immersion-Heater is switched on at the right time for the Rest-Cooking-Time
  • You have a Timer (from ... till) for to define at which the cooker should be active
  • You have a Cooking-Timer with Alarm to program how long it should Cook in the Cooker
  • You have a Pumping-Timer to program how long it should produce water
  • You can have a alarm in ..... min (for boiling eggs for example)
  • You can have a level-controlled production of hot or potable Water
  • For the pasteurization you have to put only a black tube and a heat-swapper from copper-tube into this area. Pasteurizing takes place very efficiently through the Versus-Flow-Procedure, the hot water gives the energy back to the cold water.
  • Minimal interventions at the solar-cooker is necessary (a hole must be drilled into the stove).
  • You  can use the Metamorphosis also for drying fruits etc in the cooker. There is Temperature-controller for a fan etc. and a alarm if the temperature exceeds the range
  • Now you have a multi-stage theft-protection for the Solar-cooker. One Alarm if the lid will be opened and another if the Cooker is removed. All have a loud acoustic alarm
  • You can even let the cooker follow the sun-position  automatically (energy-optimized!). A simple electric motor from a old car can be used for this.
  • Optional: You can also connect solar-cells and Acid and sealed Acid-Batteries. Independent loading-control (Battery full and empty) for a small sized Solar-plant ( 12 A max). That means the System can run with different sources, with the 110V/220V-grid, with solar-cells and acid-batteries or with NiCd.- or NimH-Accumulator
  • Optional: up to three independent voltage-sources for small-appliances like CD-Player, Walkman, TV
  • Optional you can have a telephone-notification in case of Alarm or if the food is ready. This is more for the Yuppie-Cookers. You can connect a Telephone-line or a mobile-phone and you have two Telephone-numbers to program
  • You may think now, the device is too complicated to handle! It is less complicated than       switching the programs of a TV because all Programs can be activated only by using one Program-Switch. A main aspect of the device is simplicity
  • Reliability is the other very important point and there are many measures to guarantee this: All inputs and outputs are short-cut and reverse-voltage protected. There are special parts at the inputs against high voltage
  • You can use the same device for many other functions only by loading new Software. And all the Software is free, you don’t need to pay for it! It is very simple and can be done by all PC’s.
    All Hard.- and Software is modular. So you can just take the modules you need. Click here for more Information
  • Anyway, these are some options you have with the device. But you can have your own features. Say what you want and you get it! Or make your own programming. You get the necessary Software for it!
  • Make your own Programs! You can use it also for your own Applications as a Micro-Controller-Development-System. The Basic-Compiler is free for small Programs. There is an Open-Source Software and Template for that for free. Look at System/Mikrocontroller System.html


more Information and Downloads



Short Info about the Solar Cooker

Download of the Software

Download of the Bootloader for to load the Software

More Information? Click here and download the manual!

Download of the Software for to Remote-Control the Metamorphosis and Upload of Measured Data

Build your own Solar-Cooker? Here is a good describtion of Ulog-Solar-Cooler for Tropical countries

And this is a good describtion of the Ulog- Solar Cooler for other countries

A wonderfull Homepage for all topics around a Solar-cooker

and here as well good information;     Here another page with the technical construction

A Complete Guide to Solar Cooking

Excellent overview:

Overview Solar Water Pasteurization


How does the pasteurization of water works?

IIn the free space of a Solar-Cooker you put a plastic or copper-pipe; Through this the water will be heated. After this it will pass a simple heat-exchanger (reverse-flow-principle) for to use the energy of the hot water to preheat the incoming cold water. Through this you will have a very good yield for the water-pasteurization-process. But you can Bypass this to get the hot water for tea etc.

The transport of the water works through a small pump, for example a old pump of a car for to clean the wind-screen. In this way you have the water directly where you need it for example in the kitchen. The Heat-exchanger can be delivered by Alternative Technology, if necessary also other components.  But isn’t it more interesting doing the things by yourself?

Solar-Cooker with the heat-exchanger