Power Electronics for PV and Storage Systems

In the area of power electronics for photovoltaics and storage systems, we combine our comprehensive knowledge with a unique lab infrastructure. Our research projects focus on increasing the power density and power-to-weight ratio and thus the integration density of power electronic systems. We also specialize in developing customized solutions of up to 350 kW for photovoltaics and storage systems. We design efficient and multifunctional converters for all types of on-grid and off-grid applications. Working closely with our customers and partners, our experienced engineers can find the ideal hardware and software solutions to meet all technical requirements and specifications.


Our R&D activities in the field of power electronics for photovoltaics and storage systems comprise the following:

Compact, efficient and customized converter systems

Kompakte, effiziente und kundenspezifische Umrichtersysteme
© Fraunhofer ISE
A battery inverter that can be used at outputs of 125 to 2,000 kilowatts thanks to its modular design, which makes it suitable for industrial storage systems.

Drawing on our many years of experience in developing customized power electronics for use in photovoltaics and storage systems, we work with our customers and partners to identify the appropriate specifications and system designs in terms of a variety of factors, including electrical sizes, mission profiles and climatic conditions. To help us develop compact and efficient power electronics, we use the latest semiconductor technology (silicon, silicon carbide and hybrids) and create designs with fast switching times and suitable circuit topologies. We use a variety of dimensioning tools to assist us in selecting the right components and producing the circuit diagrams and layouts for the printed circuit boards. After the parts have been manufactured externally, our technicians and engineers assemble the electrical components and take the converter stages into operation. We integrate customized and specially developed cooling systems and housing designs into prototypes and pre-production developments. We then measure the electrical and thermal performance of these components in our labs to check whether they meet the latest device-specific standards.

Innovative assembly, connections, and cooling concepts

Technology demonstrator of a 70 kVA PV inverter
© Fraunhofer ISE
Technology prototype of a 70 kVA PV inverter with optimized design and cooling technology.

In addition to the power electronics themselves, our research and development activities are concentrating increasingly on the peripheral components used in assembly, connection and cooling technology. Technological progress in this field will pave the way toward significant increases in power density and power-to-weight ratio. We use our extensive expertise to support our customers and partners in selecting suitable semiconductor modules. Our services range from optimizing module layouts and using double-pulse tests to record switching losses to measuring temperatures using fiber optics during the operation of semiconductors in the power electronics and finding the optimum way to make the connection to the cooling element. To ensure that the resulting losses can be used effectively, we work closely with other in-house experts within our institute to design optimized cooling elements, for example by using heat pipes or composite materials. We also focus on ensuring that our power electronics are cost-effective, so we choose from our wide range of standard printed circuit board technology wherever possible. For example, we can still achieve very high power densities by using copper traces in some cases and by stacking circuit boards.

Highly dynamic, flexible and resilient control systems and condition monitoring

Strukturbild eines Zustandsreglers mit Beobachter für eine Stromregelung
© Fraunhofer ISE
Block diagram of a state controller with a observer for a current control.

We design innovative bespoke control systems for our developments in the area of power electronics and for our customized converters. In addition to conventional approaches (P, PI, PID, vector control), we are proficient in developing state controllers, observers and model-predictive approaches. The mathematical description of the system and subsequent design of the associated control elements form the basis of the modelling and simulation needed to verify the control characteristics. One of our particular strengths lies in controlling complex, multi-stage power electronics with run-time optimized algorithms in the low-level programming language in both single-phase and multi-phase systems (DC and AC).

Our research and development projects regularly involve improving power quality and voltage control in grid-connected systems. We are also dedicating more attention to integrating condition monitoring and predictive maintenance approaches into our developments.

Simulations of and studies on power electronic converters for PV and storage systems

Wirkungsgradsimulation eines DC/DC-Wandlers mit integrierter Regelung
© Fraunhofer ISE
Simulation of the efficiency of a DC/DC converter with integrated control.

Every project begins with an idea followed by the planning of a concept or feasibility study. During this process, our experts identify the suitable circuit topologies, calculate the dimensions of the main components required and use a simulation to evaluate the new system.

 They also analyze, characterize and modify existing power electronic converters and systems. Furthermore, our work entails supporting our customers with their developments as and when needed, for example by reviewing circuit diagrams and layouts and by providing advice on the application of device-specific standards.

 We organize training sessions, seminars and presentations to share our expertise in photovoltaics and storage systems with industry professionals.


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R&D Infrastructure

Center for Power Electronics and Sustainable Grids