UNSW hits 19.4 percent on mass-produced solar cell – what next?

The new record was set at the University’s School of Photovoltaic & Renewable Energy Engineering in Sydney, and was verified by the Fraunhofer ISE Solar Cell Calibration Laboratory.

The levels were achieved using a patented laser process by researchers from UNSW’s Photovoltaics Technology Transfer Team working with solar technology firm centrotherm photovoltaics. They achieved the new level in June, after taking the mark from 18.9 percent to 19.3 percent in May.

Matthew Edwards, program manager of the Photovoltaics Technology Transfer Team at the school, told pv magazine that he was very happy with the progress and the opportunities it would create.

"It is quite exciting for me," he said from the university. "This is the highest confirmed low-cost, mass-producible large area solar cell ever."

The major news is expected to drive the price of this type of cell down dramatically over the coming years.

"It basically translates back to cost per watt and the cost of solar coming down to that of coal-fired electricity," he said. "At first we see a five percent drop in cost for the technology. But the nice thing about it is that when you move into the second phase, the reduction becomes around 15 percent."

Cost modeling from UNSW shows the 19.4 percent first-phase technology should mean between €35 million and €70 million a year in cost savings for the average large solar cell manufacturer. The second-phase double-sided technology at 21 percent efficiency translates to savings of between €140 million and €210 million a year for a normal large cell manufacturer.

centrotherm has already suggested that photovoltaic system costs could fall by around 20 percent by 2013, generating billions of dollars of savings worldwide if efficiency levels continue to improve.

Bringing it to market

Edwards also works a lot on the commercialization of first generation photovoltaics and is very keen to be able to make these records available soon.

His team is working with several different companies in order to bring the cells to market as soon as possible. Specifically, the group is looking to take the progress made in laboratories to mass production quickly through companies like centrotherm and several others in America, Asia and Europe.

"We generally do collaborations that run for three years," he said. "And the aim of that is to get them into mass production at the end of the three years. That is the sort of time frame we are talking about."

He continued: "Some of those operations are already past the one year mark. So we are talking about the next one year or two years or three years tops for this technology being available.

"We are really pushing University technology to try and get it out there, because we think it is some of the best technology in the world."

Technology details

The shift away from screen printing is something that Edwards sees becoming a trend in the industry due to the rough nature of the process.

The record-breaking cells were achieved on a standard p-type CZ silicon wafer that gave rise to a low-cost cell.

They were produced using UNSW’s patented Laser Doped Selective Emitter (LDSE) process, which uses a high-powered laser and a light-induced plating process to create ultra-fine metal contacts on the cell surface, leaving more area exposed to light to create more power.

The advantages of LDSE technology is its ability to boost cell efficiency with some basic modifications to existing screen-printed solar cell production lines, which are used in the majority of common mass-production systems today. The process is already in pilot production at some facilities, which offers further benefits and savings.

"Our technology can work with not only multi-crystalline, but also cheap forms of silicon, and that is because we use less high temperature processing," said Edwards.

"There is a reduction in shading loss from about seven percent down to three percent. We can get very good yields on very cheap wafers."

He revealed that the group was now working on a new technology, double-sided LDSE (D-LDSE), which optimizes both the front and rear surfaces of a solar cell to deliver efficiencies of up to 22 percent.

The group at UNSW hopes to reach efficiencies of more than 21 percent for these low-cost, first generation silicon solar cells by the end of 2012, and take that up to 22 percent in 2013.

A paper detailing the work done so far will be published in the inaugural edition of the Journal of Photovoltaics.