Yesterday, internet giant Google fired the starting gun on its ‘Little Box’ challenge. The company, which is becoming an increasingly significant player in clean technologies, from driverless cars to green energy investment, is offering a US$1 million prize for a design that successfully shrinks a 1kW inverter from its current “picnic cooler” volume to no one-tenth that size.

While Google’s stunt could be dismissed as just that, if it does find a winning concept that meets all its detailed technical criteria, the challenge could have important implications for the wider inverter market.

The miniaturisation of the inverter, be it one used in residential or utility-scale installations, is one of the main aims of all inverter suppliers currently. As Google is looking at designing a 1kw inverter that is the size of a laptop, this will require serious improvements on current inverter design.

Currently, the preferred inverter type globally for usage in residential systems is a 4kW single-phase inverter. Just under 7GW were shipped globally in 2013 and shipments are forecast to reach just under 10GW in 2018.

The closest inverter type on the market presently that meets Google’s description is the microinverter. Microinverters are typically smaller (250-300W) in size and generally use a lot of power semiconductor technology. Just under 0.5GW of microinverters were shipped globally in 2013 and this is forecast to increase to over 2GW by 2018.

One of the drawbacks of the microinverter solution is the price, which is typically US$0.20/W higher than the average single-phase inverter presently. However, recently microinverter suppliers such as Sparq Systems and APS have developed larger ‘quad’ microinverters that allow a 1kW microinverter to work with four modules. This trend of larger microinverters could be one solution to reduce the price per watt of microinverters and reduce the number of units in a PV system.

Currently component suppliers have been involved in developing the next generation of power electronics used in inverters and microinverters. Not only is size critical to the success of an inverter; so is a reduction in the number of components, as fewer components normally means better reliability and reduced failure rates. Reducing the number of components also means the manufacturing process can be streamlined and allow further cost savings. One of the other main objectives of Google’s challenge should be for the new inverter to remain price competitive as average global inverter prices are forecast to decrease by 8% per year on average for the next five years to reach US$0.11/W in 2018.

While it would have been very easy for Google to acquire an inverter or microinverter supplier in order to fulfil its needs, if it is successful in its objective of drastically reducing a 1kW inverter size, it will have made huge strides in the future roadmap of the inverter and will pose a serious threat to the existing supplier base.

PV Tech is supporting a webinar hosted by IHS on Tuesday 29 July on the changing face of the PV inverter industry. To register, click here.

Google's inverter challenge could upset the established supplier base. Image: Enphase.

Google's inverter challenge could upset the established supplier base. Image: Enphase.

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