Solar photovoltaic panels that may be in the affordable range and what is expected to be shipping soon are not great efficiency tools for getting the solar energy into electrical potential. As it improves the next step of inverting the panels direct current into the commonly used alternating current has received an upgrade in technology. A property with a photovoltaic array will need an inverter system that should be made and designed to last for more than one panel set assuming the panel’s output doesn’t increase a huge amount. Weather like hail and high winds and just dirt and the inevitable degrading of materials can be expected to make turnover and panel upgrades a likely part of any installation.

Yesterday I hit on Fraunhofer in Germany as a consultant to financial interests choosing what investments to back and the looking into Fraunhofer turned up an interesting development. Fraunhofer has made up a prototype inverter using the U.S. company CREE, Inc. metal oxide semiconductor field effect transistors (MOSFET). In an inverter the direct current that flows one way has to be switched so that in one moment the flow is going one way and in the next moment the current flows back the other way. That requires switches, which is what transistors can be set up to do, small solid-state switches. Fraunhofer has substituted the common silicon based transistors with the MOSFETs in a design that reduces the power dissipation by 30 to 50%. It’s reported that this is the first use of MOSFETs in an inverter application. That keeps the previously dissipated power on line rather than lost. Fraunhofer is claiming the efficiency rating to be 98.5%. Thus, a kilowatt (100 watts) coming out of the panels would put 98.5 watts into the system or back on the grid.

Direct Current Inverter - Fraunhofer

You’re likely reading this on a computer that has a power supply that does the reverse, converting alternating current to direct current. A quick shopping tour shows that power supplies over 80% are rare and expensive. The computer’s processor where there are million of transistors is a hot spot too, so its easy to see that a 98.5% efficiency isn’t wasting a lot of electricity by losing it to heat.

Dr. Bruno Burger, head of the Fraunhofer Power Electronics Group, says the prototype is actually a current design with the new transistors installed. If a further step is taken, such as optimizing the entire inverter specifically for the characteristics of the new transistors an added gain could be expected. The current design is using the patent-pending HERIC layout.

Which leaves us with a couple of questions. Is the patent-pending design going to come with a huge added intellectual property expense and are the CREE MOSFETs priced so that the uses will increase and manufactured volume drive the prices down for widespread adoption?

It matters, a lot. If a small arrays can be more efficient then they can be sold more widely enabling more places to self-power and make grid contributions. The benefits just go up as array sizes increase. It may save a huge amount of capital that can be used to provide a larger total installed base and sooner. Keep your fingers crossed that good sense overpowers greed in this kind of technological improvement.


5 Comments so far

  1. More Efficiency From the Solar Panel to the Grid | Solar Panels Blog on January 29, 2008 8:09 AM

    […] Original post by News and Views for Making and Saving Money in New Energy and Fuel […]

  2. solar battery charger on March 4, 2008 11:29 AM

    I have several questions:

    Will this development suit the private sector or just the industrial one?

    How much will this development improve the current solar panels’ effeciency (assuming the current cost effective solar panels harnessing 20% of the solar energy)?

  3. Louis on March 12, 2010 6:33 PM

    Will this development suit the private sector or just the industrial one?

  4. David The Solar Power Man on October 22, 2010 2:41 AM

    Terrific piece of writing, found it interesting. I’ll be including your site to my list of faves, keep up the truly great posts bud!

  5. aspergers syndromes symptoms on November 8, 2010 8:32 AM

    Couldnt agree more with that, very attractive article

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