Record-breaking solar conversion rate achieved

Solar technology company RayGen Resources and the University of New South Wales (UNSW) have collaborated to produce the highest ever efficiency rate for the conversion of sunlight into electricity: 40.4%. This puts the technology ahead of fossil fuels for energy conversion, with the most efficient coal-fired power stations in Australia running at 40% system efficiency.

The record-breaking efficiency was first achieved in outdoor tests in Sydney, before being confirmed by the National Renewable Energy Laboratory (NREL) at its outdoor test facility in the United States. It was achieved using a system that enables sunlight that is normally wasted by solar cells to be converted to electricity.

RayGen Resources provided design and technical support for the high-efficiency prototype, drawing on the same technology that sits at the heart of the company’s Concentrated Solar Photovoltaic (CSPV) solution that is capable of producing the world’s lowest-cost source of renewable energy for utility-scale purposes. US-based company Spectrolab provided some of the cells used, while funding was provided by the Australian Renewable Energy Agency (ARENA).

As explained by ARENA CEO Ivor Frischknecht, “The clever solution combines advanced triple junction cells with cheaper conventional silicon cells to boost power output.” A custom optical bandpass filter captures sunlight which is normally wasted by the triple junction cells by splitting it into different spectra and directing some of it into a silicon cell, thus converting it to electricity at a higher efficiency than the solar cells themselves ever could. The filters reflect particular wavelengths of light while transmitting others.

Dr Mark Keevers, the UNSW solar scientist who managed the project, explained that the use of commercial solar cells means the efficiency improvements are “readily accessible to the solar industry”. Professor Martin Green, director of the Australian Centre for Advanced Photovoltaics (ACAP), added that the use of focused sunlight makes the results “particularly relevant to photovoltaic power towers being developed in Australia”.

RayGen CEO Bob Cart said the result marks an exciting milestone in enabling utility-scale solar power to become a more viable alternative to fossil fuels, one day becoming “our primary form of electricity generation”. He said, “In practical terms, we’ll be looking to apply the outcome of the testing to the work we’re doing with companies like China Intense Solar where addressing the acute air pollution problems of the world’s most populous nation is a major priority.”

By March 2015, RayGen will commission the first site deployment of a CSPV tower in regional Victoria. It has also fast‐tracked its project timeline with China Intense Solar to deliver a 10 MW commercial‐scale operation in Qinghai province by August 2016 that will be capable of powering thousands of homes. Meanwhile, RayGen Chief Technology Officer John Lasich has said the company is capable of lifting energy conversion levels even higher, expecting to achieve “close to 45% system efficiency in the next few years”.

The achievement is outlined in a paper expected to be published soon by the journal Progress in Photovoltaics. It will be presented at the Asia-Pacific Solar Research Conference, which is being held at UNSW from 8-10 December.