Your daily dose of photovoltaic technology developments and solar news

In the few years since the PV cell and module manufacturing industry first hit the radar, the identities of the winners and losers in the race to supply equipment have started to emerge. While some companies can genuinely claim to have been involved in the solar industry for some time, the majority are relatively new on the scene. This is hardly surprising, as the explosive growth in demand spurred any company with matching competences into action.

The American Recovery and Reinvestment Act has now been passed, and there is much talk about what this will actually mean for the solar industry. The final version of the stimulus bill amounts to US$789, which will be the government’s most expansive economic rescue package since The Great Depression, even after the cuts.

News of credit crunch woes filtering down the lines over the past few months has instilled a sense of frugality in all industry sectors. While the credit crisis has indeed affected the PV industry, German banks, investors and creditors have claimed that the financing of small PV systems in the private sector seems not to be endangered.

The rapid expansion of high volume manufacturing to meet growing demand in recent years has highlighted the development of increasingly higher throughput machines. This is particularly true in the critical bottleneck process of module assembly, specifically characterised by tabbing and stringing steps. Significant productivity improvements have come about with the development of integrated, highly-automated tabbers and stringers from a range of equipment vendors. However, module assembly remains the most expensive step in conventional c-Si cell production.

Transparent conducting oxides (TCOs) are a special class of materials that can simultaneously be both optically transparent and electrically conducting and, as such, are a critical component in most thin-film photovoltaics. TCOs are generally based on a limited class of metal oxide semiconductors such In₂O₃, ZnO and SnO₂, which are transparent due to their large band gap energy and can also tolerate very high electronic doping concentrations to yield conductivities of 1000S/cm or higher.

Materials innovation in solar photovoltaic manufacturing has long played a key role in efforts to raise cell and module conversion efficiencies, improve overall device performance and reliability, and lower the overall cost per manufactured watt. Research and development in areas such as ultrathin-silicon wafering and replacement films for thin-film PV transparent conductive oxides often garner much of the industry’s attention.

Owing to the huge demand for photovoltaic products, the market is still very attractive for investments in production facilities. Nevertheless, the increasing number of competing photovoltaic manufacturers and the decrease in governmental subsidies require substantial and continuous cost reductions.

The PV industry has seen some incredible growth in the last five to eight years. This growth is essential in order to fulfill the challenging targets this industry has set itself to ensure it becomes an economical viable alternative energy source. A negative result of this growth, however, is the inefficient supply chain, where there is a lack of balance between demand and supply. The industry is going from one bottleneck to another.

Formation of the pn-junction for charge carrier separation is one of the key processes of a modern high-volume solar cell production. In silicon wafer-based solar cell technology this is achieved by diffusion of phosphorus atoms in boron pre-doped wafers forming a sub-micron shallow n-type emitter in a 200μm-thick p-type base.

In recent years, a new generation of solar electric products has emerged from the lab into the global market: thin-film technologies that employ approximately 1% of the active, expensive photovoltaic material used by standard crystalline-silicon cells. Through a combination of cost advantages and new product applications, cadmium telluride (CdTe), amorphous silicon, and copper-indium-gallium-selenide (CIGS) thin-film PV have the potential to foster a paradigm shift toward distributed electricity generation at cost parity with other forms of energy.