Revolutionary discovery in solar power research
TUT is at the forefront of developing the electrical properties of solar photovoltaic power systems and solutions for integrating solar power into the grid. Professor Teuvo Suntio’s discovery concerning photovoltaic inverters reshaped the landscape of solar research.
The solar power market is expanding rapidly. For example, in 2011 the global solar energy generation capacity increased by as much as 75 per cent and totalled 70,000 megawatts.
Up until recently, the functions of photovoltaic (PV) power systems have been poorly understood. Technical expertise has been lacking and malfunctions have been all too common. The systems have also been observed to cause problems with power quality and disruptions in the power grid.
TUT is globally recognized as a forerunner in the development of new PV technology. Thanks to a breakthrough discovery in 2006, the University has become a leading authority in the development of PV power systems and related grid integration solutions.
“An inverter is always needed when PV electricity is integrated into the grid. I had a sneaking suspicion that the generally used principles of inverter design were invalid. It turned out that I was right. Our findings confirmed my assumption that a PV cell is a non-ideal current source,” says Professor Teuvo Suntio from the Department of Electrical Engineering.
“To address the shortcomings, we needed to form an overall picture of photovoltaic power systems, environmental factors and grid-compatibility.”
Expertise in demand
Suntio’s discovery instigated a paradigm shift in PV electricity research and revolutionized the design principles of inverters. The new systems that are built based on Suntio’s approach have proven to be considerably more reliable than the old ones.
Expertise in the field has made TUT a sought-after collaboration partner in research and education.
“Our projects are attracting growing international attention not only within the scientific community but also among companies”, says Professor Seppo Valkealahti, Head of the Department of Electrical Engineering.
In 2008, the global manufacturer of power and automation technologies ABB and TUT launched collaboration that continues to this day. The two organizations have, among others, joined forces to pinpoint the optimal structure of photovoltaic power plants and develop new PV inverters. ABB has patented the technologies that the partners have developed during the contract period.
“In the past three years, four doctoral students who wrote their dissertation on photovoltaic power systems have graduated from TUT. They have all been hired by ABB,” says Valkealahti.
One of them is Dr Joonas Puukko who completed his doctorate in late 2012.
In his dissertation, Puukko analyses the dynamic properties of grid-connected PV inverters and presents a method for modelling the effects of their non-ideal properties. He developed guidelines concerning the sizing of inverter power-stage components and for designing a control system that ensures the stable operation of PV systems. The proposed methods are now in use at ABB.
“The University’s collaboration with ABB demonstrates that TUT responds to industry needs. And it helped me get a job in an industrial sector with strong potential for growth”, states Puukko.