Better, Smaller Solar Inverters On The Horizon?

Silicon carbide SiC based solar inverters

Chips made from a material called silicon carbide (SiC) will result in super-efficient and smaller inverters according to GE.

A solar inverter is a device that converts DC (direct current) electricity produced by solar panels into mains-type AC (alternating current); suitable for use in a home and for exporting to the mains grid.

Today’s solar inverters are reasonably efficient – for example, inverters commonly used in commercial and residential solar installations have a maximum efficiency of around 97 – 98%. While inverters are a lot better looking than even just a few years ago, they are still rather bulky; particularly those used in utility scale installations.

An alternative to bulky boxes is the microinverter, which is mounted on the back of or close to a solar panel – but microinverters are needed for each module, aren’t suitable for every situation and they add cost to an installation.

Silicon carbide, also known as carborundum, could help address the bulk issue and provide other benefits.

“This material stands to revolutionize power electronics,” according to Danielle Merfeld, who is the global technology director for electrical technologies and systems at GE Global Research.

SiC could reduce the size of a one megawatt inverter by an incredibly 35 percent. Power conversion efficiency could also be increased by about 1 percent. This may not sound like a huge leap forward in efficiency, but in a large scale solar farm, the production and financial benefits would be significant.

The use of silicon carbide could also mean cooling of some large inverters can be switched from water cooling to air.

A prototype SiC based inverter is already in operation at a hybrid gas and solar power station in Berlin, Germany.

Silicon carbide occurs naturally in moissanite; but is very rare, so nearly all silicon carbide sold in the world is synthetic. Production is complex – GE says making a SiC chip involves up to 300 steps in a clean room.

A GE-led consortium is currently building a shared fabrication plant that will develop and produce silicon carbide power devices on six-inch wafers. Whether and when the technology will be available in smaller inverters is unclear.

The quest for smaller inverters for domestic applications was thrust into the spotlight last year when Google offered a million dollars to the person or team that comes up with the best design of a unit around the size of a notebook computer. We haven’t heard much more about the competition; but according to the timeline, applicants were required to submit a technical approach and testing application on July 22 this year. The winner will be announced and the inverter unveiled in January next year.

Related: Micro, String And Central Inverters.