Development of thin film solar technology

3M has teamed up with the National Renewable Energy Laboratory (NREL) to develop technology for the creation of low-cost thin-film photovoltaic modules.The $7.33 million partnership will also include concentrating solar power and biofuel technology development. The work ranges from jointly identifying and developing critical aspects of renewable energy technology to accelerated testing of 3M designs and scaling-up successful prototypes for commercial production.

 

Both organisations will work to develop and test new moisture barrier films and flexible packaging for thin film solar cells made of semiconducting layers of CIGS, or Copper Indium Gallium Diselenide. CIGS cells have achieved a record efficiency of 19.9 percent at NREL. But to become commercially successful, manufacturers need to both increase module performance and reduce manufacturing costs. The solar cells are expected to work effectively for 20 years. That means they will need to be encapsulated in a flexible material that is transparent to light, but also provides durable protection — and doesn't add significant costs.

 

NREL will conduct accelerated stress tests, including temperature, humidity and irradiance tests, to establish failure barriers on as many as three types of 3M CIGS designs. The Lab and 3M will jointly interpret the results with the aim of establishing module standards for a 20-year lifetime. Principal investigator Mike Kempe said much of the testing will revolve around measuring the rate of water vapour transmission in moisture barrier samples. "We test their moisture barrier materials to determine if they give adequate protection to the CIGS cells,""They want expert eyes looking at these materials before they go to the PV industry." Kempe said.

 

The performance and potential of thin-film materials are excellent, reaching cell efficiencies of 12%-20%; prototype module efficiencies of 7%-13%; and production modules in the range of 9%. Annual manufacturing volume in the United States has grown from about 12 megawatts (MW) per year in 2003 to more than 20 MW/yr in 2004; 40-50 MW/yr production levels are expected in 2005 with continued rapid growth in the years after that.

 

Future module efficiencies are expected to climb close to the state-of-the-art of today's best cells, or to about 10%-16%. Costs are expected to drop to below $100/m2 in volume production, and could reach even lower levels—well under $50/m2, the DOE/NREL goal for thin films—when fully optimized. At these levels, thin-film modules will cost less than fifty cents per watt to manufacture, opening new markets such as cost-effective distributed power and utility production to thin-film electricity generation.