NREL’s Little Box Challenge Won By Belgium’s Red Electrical Devils

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The National Renewable Energy Laboratory’s “Little Box Challenge” — a competition designed to spur the creation of smaller inverters for use in interconnecting solar energy systems to the power grid — has been won by Belgium’s Red Electrical Devils (a team from CE+T Power), according to a recent announcement from Google and IEEE.

Google Little Box Challenge for invertersThe win nets the research team $1 million in prize money for its work to show that “inverters can be the size of a tablet or smaller rather than the size of a picnic cooler.”

The winner of the competition was selected following testing and analysis of the various submissions at The Energy Department’s National Renewable Energy Laboratory’s (NREL) campus in Golden, Colorado. Submissions were brought to the Energy Systems Integration Facility (ESIF) in Golden back in late-October 2015.

“The overall idea was to test these inverters in a similar fashion to how they would be used out in the field,” stated Blake Lundstrom, the NREL project lead.

Here’s more via an email sent to CleanTechnica:

The first step was to verify that the inverters met all critical safety-related specifications and then to simply turn the inverters on and see if they functioned. Next, was a three-hour procedure to operate the inverters at a number of different operating points and to verify that key specifications were met throughout the three hours. After these challenges, the field of eighteen finalists was narrowed to the remaining inverters that would proceed to the third round.

Those final inverters were subjected to a 100-hour simulation of real-life conditions, including a direct-current source of electricity that emulated a solar power system, with rapid ramp-ups and ramp-downs in power typical of an intermittently cloudy day, as well as a realistic, changing load typical of a residence that the inverter needed to supply. Each inverter had to meet most of the same specifications required of commercially-available inverters.

“We were checking that all the specifications were met, under realistic conditions that a similar solar inverter in the field would experience, and evaluating their thermal performance over the long term — those are the key things that we were looking for over those 100 hours,” continued Lundstrom.

Following review by judges from Google, the IEEE Power Electronics Society, and NREL, the Red Electrical Devils were unanimously selected as the winner.

Their inverter had a power density of 143 W/in3-far greater than the minimum requirement of 50 W/in3 and 50% higher than the nearest competitor-and a volume of only 14 cubic inches, smaller in volume than a cube measuring 2.5 inches on each side. The winning inverter also performed better on measurements of electromagnetic compliance (the amount of electrical noise emitted from the unit).

Shrinking inverters by an order of magnitude and making them cheaper to produce and install will enable more solar-powered homes and more efficient distribution grids, while helping bring electricity to remote areas. A key factor in the winning inverters was the use of wide bandgap semiconductors, a technology that enables power electronics to operate at higher voltages and temperatures, allowing them to transmit more energy through a smaller volume.

“Wide bandgaps offer a lot of advantages over traditional silicon that enabled teams to hit some of the miniaturization and efficiency targets that were needed to be successful in the competition,” noted Lundstrom. “Not every single team used wide-bandgap devices, but the vast majority did.”

“The Little Box Challenge actually forced people to try to optimize space, and a nice outcome of that is that some of the techniques to do that are going to be pretty helpful for other aspects of inverter development,” concluded Lundstrom. “For example, once you have a device that is almost entirely integrated onto a printed circuit board, it’s easier to manufacture. Plus, some of the teams were able to incorporate all this innovation without adding any additional cost to the inverter and in some cases these designs may result in reduced inverter cost when mass-produced.”

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James Ayre

James Ayre's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy.

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10 thoughts on “NREL’s Little Box Challenge Won By Belgium’s Red Electrical Devils

  • We are still piecing together the info. Nice to hear about cost being equal or less than conventional inverters. The general idea is they will follow the cost curve of electronics rather than mechanical. The aim should be 10cents watt by 2019 for battery inverters. On Grid inverters should hit 7cents watt by then. The efficiency of these inverters is about 96%…which is respectable. A shoe box full of the winning size would be 60 kw of inverters. That would fill the back of a pick up with conventional sized inverters.

  • “and 50% higher [power density] than the nearest competitor”
    holy crap, they must have done some black magic there 🙂

  • The Belgian winners even had to translate their dimensions into those weird “cubic inches”. Off the top of your head, how many of these go into a pint?

    • Let’s get real. Give us the measurement in furkins. Something we can work with.

      • A furkin is much too large a measure! You don’t measure your height in Siriometers.

        May I recommend Board feet? Seems much more appropriate…

        • If a furkin is too large then go with a pony….

  • Quote a famous Belgian, Eddy Wally: “Waauw! “

  • I imagine a few changes will be needed before they can be massed produced. The price point goal was on the order of $100/kW. These 2.2kW inverters could sell @ $220. Wow! Who will make and sell them? When? Ten for me please.

    • Did you see a “price point” somewhere? I would like to see that myself, can you refer me to the info?

      • @vensonata
        Well no, Sorry. I don’t have a price point reference. I just remember reading the original goal from years ago was to reduce the size of a 5 kW “picnic cooler” inverter to the size and COST of an iPad. If the 5 kW “picnic cooler” cost $5k and the iPad cost $500, then the cost per kW would be roughly $100/kW. In my own words the goal was to reduce the size and the eventual mass produced COST by an order of magnitude. Of coarse the cost of 5kW inverters and ipads is less today, but that’s still roughly the same ratio.

        However, the cost was never directly a part of the challenge. That comes later. The next step is the mass production and cost reduction. Hopefully the massive resources of Goggle will accelerate this process.

        Thank you for your many thoughtful comments. I’m sorry I misled you into thinking I had real cost data.

Comments are closed.