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uni'wissen 02-2013_ENG

op self-sufficient systems, scientists in Reindl’s laboratory are studying solar cells that generate enough power for the sensors even in low-light areas such as forests or inside buildings. In addi- tion, they are developing miniature generators that produce energy out of the variation in tem- perature between day and night. However, the amount of energy it is possible to glean from such sources is low and subject to great fluctua- tion, making the methods very expensive. Batteries, on the other hand, have the disad- vantage that they only have a limited energy supply and need to be changed regularly. The less energy radio transmission processes need, the longer the life of the batteries. Reindl has developed a sleep-wake up technology for wire- less sensor networks that requires 10,000 times less energy for transmission than comparable standard systems: It needs a mere 10 micro- watts of power – a radio receiver powered by a standard round cell battery equipped with this technology achieves a lifespan of roughly seven years. A Baby Monitor for Photovoltaic Systems The wake up strategy is the technological foundation of SmartExergy WMS, a start-up founded by Dr. Tolgay Ungan, one of Reindl’s former PhD students, and the businessman Pat- rick Steindl with support from the entrepreneurial office of the University of Freiburg and an EXIST entrepreneurial grant from the German Federal Ministry of Economics and Technology. The EX- IST Program provides funding for spinoffs de- rived from innovative tech-oriented research projects at universities with good economic pros- pects. SmartExergy WMS delivers monitoring technologies that make the operation of photo- voltaic systems more efficient, safer, and easier to service. The university spinoff has received several awards: After winning the Freiburg Inno- vation Prize and an award at the entrepreneurial competition “start2grow” in 2012, the company won a CyberOne High-Tech Award and, most re- cently, the Baden-Württemberg Environmental Technology Prize in the category instrumentation and control engineering in 2013. Standard monitoring systems work according to the principle of comparison: The system mea- sures the performance of the strings, which con- sist of up to 20 solar modules, and compares the actual performance to the target performance. Only when these two values deviate from each other to a certain extent do the operators search for and analyze the errors on location. By con- trast, the wake up technology developed by SmartExergy WMS works like a baby monitor: Each and every photovoltaic module is moni- tored by a wireless sensor. When the perfor- mance of a module drops, the sensor sets off an alarm and corrects the error immediately. The time gained by the precise localization and anal- ysis of the reason for the error makes photovol- taic systems much more efficient, since even minor influences like dirt on the modules can have a major impact on their output. The technology developed by SmartExergy WMS also provides a solution to the string prob- lem that often plagues photovoltaic systems, in which a single defective module or a module that “Everywhere where the safety of a structure is in doubt but needs to be guaranteed, we can use radio sensors to obtain information about its current state” Monitoring modules individually: The wake up technology devel- oped by SmartExergy WMS, a spin-off of the University of Freiburg, enhances the performance and safety of photovoltaic systems. Photo: Michel Angelo/Fotolia 18