Research and Development      

Multi-functional solar systems for regional energy and food autonomy have been inspired by nature, which means that they are subject to constant further development and adaptation. The R&D Department of Sunventional International is therefore continuously working to optimize already established technologies, but also to develop new, complementary concepts.

Below is a brief list:

• Energy Power Greenhouse – EPG: The existing linear lens systems SunRay are integrated into modular grids. This ensures quick assembly into commercially available greenhouses and also allows for special designs.
• Pointedly concentrating lens optics (SunString) for ideal combination with high performance photovoltaic cells (so-called “Triple Junction” cells) and cavity receivers for high temperature generation and fiber optics
• Booster mirror configuration instead of lens systems for areas with a high proportion of diffuse radiation
• New type of Fresnel lenses on wheels, based on fluoride foils
• Integrated “chimney casing” for air conditioning, lighting control, water recovery and hot water generation

EPG greenhouse in the Tamera solar test field (l.) and concentrating lens optics with high performance photovoltaic cells for fiber optics systems, constructed at Sunvention in Lörrach (r.).

“Stand Alone Systems”

The SunPulse machines and later the Y Machine can in principle obtain heat energy for its operation from the most varied sources of heat and heat reservoirs. The following models are being developed in addition to the stationary EPG lens hot oil storage system:

• Highly efficient thermal solar collectors (vacuum collectors, CPC collectors, booster collectors) generate hot pressurized water at approx. 170° C and 15 bar, store it in pressure tanks and thereby allow for around the clock operation of the Stirling machine. The solar collectors are installed permanently on the south side of the roof. The Y Machine is located in the basement of the house, as is the pressure accumulator, which has been retrofitted with an auxiliary (bio-)burner for long periods without sun. The system operates as a combined heat and power generation system, which means that it simultaneously produces the electrical energy as well as the heat necessary for the house. Through the addition of a chiller, cooling can also be provided during the summer.
• A system is being developed for settlements, farms and larger building complexes that obtains solar energy via light, precise, fixed-focus mirrors, stores it in thermo-chemical and/or eutectic (salt mixture) accumulators with a high energy density and thus operates Y machines around the clock with an output that is modularly adapted to the respective needs.

Further possible uses of the SunPulse machines and the Y machine:

The Sunvention machines are suited not only for electricity generation. They can also perform much mechanical work directly, such as sawing, drilling, grinding etc., without making a detour via electrical power. They can therefore be used efficiently and economically for work in workshops, grain processing, juicemaking and many other things. This direct mechanical use is especially suited for decentralized structures in rural areas or in villages. Sunvention International is developing suitable connections between the Stirling machine and other equipment via belt drives or hydraulic coupling.

A further use is for air compression for storage in pressure tanks and for operating pneumatic tools. Oxygen can also be separated from the ambient air with the help of compressed air via special filters and it can be stored in simple bladder accumulators. Here, Sunvention is cooperating with the inventor Horst Wagner. Oxygen is ideal for creating high temperatures for burning ceramics, in metallurgy, to burn wet biomass cleanly and for smokeless stoves and ovens. But it can also be used very advantageously for oxygen enrichment of bodies of water.

Solar cooking stove in the solar test field at Tamera, Portugal

Solar cooking

In the EPG, plant oil with a temperature of around 200 degrees Celsius is generated and from there it enters the hot oil tank. This storage medium can be used for solar cooking around the clock. The hot oil is led through double-walled pots, which means that the heat is used directly for cooking, baking or deep-frying. In addition, steam is generated through heat exchange. This makes it possible to steam vegetables, sterilize medical instruments, desalinate water and many other things.

Solar I-Roof drying facility

This is a simple system that is excellently suited for conducting heat from houses in tropical countries. Hot air is generated from black roofs (I-Roofs) over which ETFE foil has been stretched and it can be used for drying seaweed, fruits, etc. In addition, drinking water can be obtained through re-condensation of the humid air.

The I-Roof can also be used for air exchange and for the air conditioning of buildings. The hot air that flows off the roof creates a suction that draws the air out of the building. If this is connected to a system of underground channels, the building is cooled in the summer and heated in winter.

Further main areas of research

• Cooling generation through the reversible operation of Stirling machines. Concentration on the Y machine with direct generation of cold water.
• Pneumatic precision fixed focus mirror for stand-alone systems, high temperature process heat, 24 h solar kitchens with accumulators.
• Influencing heat transfers and evaporation processes through electrical fields: Compact heat exchangers for many purposes such as ocean water desalination or water reclamation.
• Light guiding, light distribution and light storage systems.