Thin film solar modules: the low cost, high throughput and versatile alternative to Si wafers

Abstract

Thin film solar cells (TFSC) have passed adolescence and are ready to make a substantial contribution to the world's electricity generation. They can have advantages over c-Si solar modules in ease of large area, lower cost manufacturing and in several types of applications. Factors which limit TFSC module performance relative to champion cell performance are discussed along with the importance of increased throughput and yield. The consensus of several studies is that all TFSC can achieve costs below 1 $/W if manufactured at sufficiently large scale >100 MW using parallel lines of cloned equipment with high material utilization and spray-on encapsulants. There is significant new commercial interest in TFSC from small investors and large corporations, validating the thin film approach. Unique characteristics are discussed which give TFSC an advantage over c-Si in two specific markets: small rural solar home systems and building integrated photovoltaic installations. TFSC have outperformed c-Si in annual energy production (kWhrs/kW), have demonstrated outdoor durability comparable to c-Si and are being used in MW scale installations worldwide. The merits of the thin film approach cannot be judged on the basis of efficiency alone but must also account for module performance and potential for low cost. TFSC advocates should promote their unique virtues compared to c-Si: lower cost, higher kWhr/kW output, higher battery charging current, attractive visual appearance, flexible substrates, long-term stability comparable to c-Si, and multiple pathways for deposition with room for innovation and evolutionary improvement. There is a huge market for TFSC even at today's efficiency if costs can be reduced. A brief window of opportunity exists for TFSC over the next few years due the Si shortage. The demonstrated capabilities and advantages of TFSC must be proclaimed more persistently to funding decision-makers and customers without minimizing the remaining challenges.

The effect of front ZnO:Al surface texture and optical transparency on efficient light trapping in silicon thin-film solar cells

“…Focusing on these figures, thin-film amorphous silicon performs better than crystalline silicon due to a lower temperature coefficient for power loss. 5 Thus, the aim of future research and development in the area of thin-film silicon solar cells is low cost annual energy production rather than merely high nominal efficiency.…”

“…5 Even though thin-film solar cell production based on copper-indium diselenide ͑CIS͒, cadmium telluride ͑CdTe͒, and amorphous silicon had comparably small market shares in 2004 of about 0.25%, 1.1%, and 3.9%, respectively, these concepts are believed to be candidates for a significant production volume in the future. [5][6][7] Thin-film solar cells might be among the very few photovoltaic techniques to reach the very low cost target of ϽUS$ 1 / watt. Such low costs are required for photovoltaics to compete with retail electricity prices but, in the intermediate term, this can only be achieved by increasing the production capacity significantly.…”

“…Such low costs are required for photovoltaics to compete with retail electricity prices but, in the intermediate term, this can only be achieved by increasing the production capacity significantly. 5,6,8 However, in the case of CIS and CdTe thin-film technologies, the use of nonabundant materials like In, Se, and Te may mean that these materials will become a dominant price factor in mass production. 6 Silicon is an abundant material.…”

Universality of non-Ohmic shunt leakage in thin-film solar cells

“…[1][2][3] Consequently, a wide variety of these technologies, including amorphous and microcrystalline silicon ͑a-Si: H / c-Si: H͒, 4 cadmium telluride ͑CdTe͒, copper indium gallium diselenide ͑CIGS͒, 5 and organic photovoltaics ͑OPVs͒, 6 are being developed and commercialized. These developments have necessitated a better understanding of thin film solar cell device physics, including important module performance variability issues.…”

Analysis of the silicon market: Will thin films profit?

“…Note that this is based on single-module list prices; for systems modules are sold in bulk, resulting in typical prices about half of that. As the thin-film PV industry does not suffer from the present scarcity of silicon, it is legitimate to ask whether the thin-film PV industry may profit from the silicon feedstock problem (Rogol and Fisher, 2005;Unzalu, 2005;Green, 2006;Hegedus, 2006;Swanson, 2006). We studied this issue by thoroughly analysing the present (updated until April 2006) and future (2010) PV market.…”