Energy-efficient Chokes for Photovoltaic Plants: Low-loss, Low Stray Fields and Compact Design

Power inverters in photovoltaic plants convert the direct current originating from the solar cells into alternating current. It is desirable that a plant yields a maximum of energy at low cost from the sun’s radiation on the connected photovoltaic modules. The direct current from the modules must be converted into a sinusoidal waveform and be converted into the values required by the grid. So-called filters consisting of capacitors and filter chokes ensure that the current being fed into the grid exhibits a sinusoidal waveform. SMP has designed high-performance, low loss chokes which meet the constantly increasing requirements of solar technology.

Developed by SMP especially for solar power applications, the materials used have low magnetostriction and exceptionally low eddy current and hysteresis losses. This means that the inverters in which they are used are highly efficient, so that a larger proportion of the generated power can be fed back into the grid, resulting in a faster return of investments. This is because the cost-effectiveness of a photovoltaic plant is directly related to the inverter’s efficiency.

Besides low losses, other requirements for components in power converters are low-intensity stray fields. SMP chokes achieve this through an encapsulated design. This offers the advantage that other components can be placed in close vicinity to the chokes without the risk of any magnetic interaction. Compact choke design is another important aspect. In comparison to conventional designs, SMP chokes occupy 25 percent less volume. Moreover, SMP chokes operate quietly, which allows their use in residential areas.


Solar technology applications rely on components with highest energy efficiency, explains Stefan Schauer, technical sales manager at SMP. Manufacturers attach great importance to component efficiency, and its value must be as high as possible. Using SMP chokes, today's power converters can reach efficiencies of 98%. When using low-loss chokes, more power will be left to be fed into the grid.

For use in inverters and converters in wind turbines and rail vehicles, and other applications in the field of drive control, power electronics, instrumentation and control, SMP supplies chokes and filters for frequencies up to 200 kHz and current ratings up to 1000 amperes. Depending on their application, the inductive components are constructed either as single-conductor chokes for high-current applications, individual chokes, choke modules or LC filters. These components offer a high energy storage capacity at low volume, reduced losses, good EMC characteristics and a cost-conscious design. SMP manufactures all components to customer specifications using in-house developed powder composites. All products are RoHS and REACH-compliant and the materials used are UL-listed. To allow for a wide range of requirements, components can be made to all common standards.