With photovoltaic panels the solar energy is harvested, but getting the resulting electricity to a useful form is still to go.  Solar panels make direct current; while the homes, businesses and the grid use alternating current.  Or simply put the electrons all stream steadily one way with direct current called ‘DC’ and the electrons stream back and forth 60 times a second in North America and 50 per second in most of the rest of the world as alternating current called ‘AC’.

Now the reversing of the electrons isn’t a problem as there isn’t a mass to speed up, slow down, stop and reverse.  But getting from DC to AC current has always had a price.

Dr. Heribert Schmidt at the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, Germany brainstormed a switching trick making it possible to cut the losses of a series-production inverter in half and increase the efficiency from 96 to 98 percent.

Dr. Heribert Schmidt and his New HERIC Inverter. Image Credit: The Fraunhofer Institute for Solar Energy Systems. Click image for the largest view.

Dr Schmidt had often pondered about the switching plan of an inverter while in his office.  The story is in sudden flash of inspiration a solution that was ingeniously simple came to mind. He immediately went to get an inverter from the laboratory, laid a few new strips and installed two additional semiconductor switches. Then it required only a little bit of work on the controls – and the proof came from testing. That’s how the electrical engineer holding a doctorate in electrical engineering, described the revolutionary step he found.  The loss can be halved and the degree of effectiveness could be increased from 96 to 98 percent.

While solar panels grab the headlines the good Doctor’s idea has immense implications.  Inverters work both ways although differently, and the idea when described in more detail may have applications for AC to DC as well.  Getting from AC to DC with more efficiency could have much further reaching impacts far faster.  Just think of all those charging bricks, power supplies, welders, it’s a huge list.

For DC to AC single-phase feed inverters there are three essential parts: the buffer capacitor at the input which provides intermediate storage for the direct current from the solar generator; the inverter bridge with four semiconductor switches that cut the direct current by rapidly switching on and off and as a third component, the inductor at the output that converts the alternating current into the correct sinus current.

Dr. Schmidt knew a large portion of the efficiency loss is caused by the return of current between the output inductor and the input capacitor. The question therefore was how to prevent this.

Dr. Schmidt explains a sudden inspiration, “That‘s easy.  If I decouple the capacitor and the inductors completely from each other at certain intervals, then it is impossible for a return current to flow, and electro-magnetic disturbances cannot occur at the input as a result of voltage spikes.”  He immediately had his invention patented and has named it HERIC® topology and has begun to develop a new series of devices with the SUNWAYS company in Konstanz, Germany.

Experts were astonished, and awards and recognition followed quickly, this is by far the best device in this performance category. In the meantime, an encompassing patent has been awarded to the basic idea and the Fraunhofer-Gesellschaft is in negotiations with additional licensees.

Naturally everyone is quite pleased.  The director of the institute, Professor Eicke Weber, emphasizes, “In 2009, a world record of more than 99 percent efficiency was set for inverters.”  Dr. Schmidt has been with the Fraunhofer Institute for Solar Energy Systems ISE since 1988 and is an experienced inventor with more than 20 patents awarded. The HERIC® patent is providing the institute with lucrative licensing agreements – and Heribert Schmidt with the Fraunhofer Prize.

It may not impress scientists outside of the EU, but the Joseph von Fraunhofer Prize is significant.  The prize has been awarded by the Fraunhofer-Gesellschaft every year since 1978, in recognition of outstanding scientific work by members of its staff leading to the solution of application-oriented problems. Over 200 researchers have had their work honored in this way. This year, three prizes will be awarded – each valued at 20,000 €.

The good Doctor’s brainstorm looks like a big payoff.  This writer would suggest taking the insight and developing an AC to DC inverter.  Think battery chargers, where efficiencies fall far short of 99%.  Hit that and the world really will sit up and notice.


2 Comments so far

  1. Anonymous on June 9, 2011 8:18 AM

    […] where efficiencies fall far short of 99%. Hit that and the world really will sit up and notice. A Better Solar Panel Result | New Energy and Fuel Google Traductor __________________ Para los fundamentalistas de lo correctamente escrito, soy […]

  2. Dave on June 11, 2011 4:16 PM

    His discovery isn’t exactly new and there is predating IP to his making the degree of protection his offers potentially in question. A lot of inverter and power converter technology has been around along time > 40 years and credit should be given to where it belongs namely prior inventers rather than grand standing as he has been. Most new inventions of merit comes from industry not research institutes. Research centers try to generate press and all too often cross the line.

Name (required)

Email (required)


Speak your mind