High Speed, Energy Efficient Manufacturing of Cadmium Telluride Solar Cells

Photovoltaic cells (the main component of solar panels) play a large part in an international effort to improve global resilience to inevitable future energy supplies shortages from fossil based fuels. The majority of photovoltaics (PV) are currently manufactured from silicon (1st generation), but the fastest growing market share belongs to Cadmium Telluride (CdTe) thin film PV (a 2nd generation technology). Because CdTe offers many advantages over crystalline silicon such as cost, availability and weight, thin-film CdTe solar cells are the basis of a new PV technology with a major commercial impact on solar energy production.

Unfortunately, like silicon, CdTe suffers from the need for substantial energy input during manufacture which means that energy payback period is typically in excess of 2 years. This paradoxical problem with CdTe could be partly overcome if new manufacturing technologies could be developed to substantially reduce process energy and allow for the substitution of alternative materials for their construction, which also supports the objective of reducing their energy footprint.

The technological advancements to be made within this project will be based around thin film deposition techniques (sputtering) and novel heat treatment (laser annealing) of these thin film CdTe layers. These processes will be monitored in order to predict and detect faults, minimise the energy requirement and improve process speeds.

The project objectives will be reached by bringing together a number of research groups from different disciplines: sustainable manufacturing, photovoltaics and laser processing. The investigators involved from these research groups have extensive experience in their respective fields, access to extended knowledge within their groups, and world-class research facilities. These attributes alongside a carefully planned programme of work with risk management strategies will significantly contribute towards project success.

The overall impact of the proposed project in manufacturing will include: substantially reduced energy demand to produce solar panel systems; the potential to initiate UK industry for the manufacture of CdTe PV; cheaper, lighter, more versatile PV for a wide range of competitive applications; and generation of new academic and industrial knowledge in thin film deposition and laser annealing.

There are currently no UK based CdTe PV manufacturers, but there are a number of companies that supply equipment suitable for the manufacture of these products. It is our intention to assist these companies to benefit from our research within the next 5 years by collaboration with them directly during the project. As examples, Power Vision Ltd produces sputtering machines suitable for CdTe and by involving them in the project, we will communicate the potential for producing machines with the 'built-in' capability of 2um CdTe deposition and the potential market opportunities this could have. Similarly the other industry partner in this project, M-Solv Ltd, have developed a One Step Interconnect process for silvering and scribing PV cells, which should be directly compatible with our proposed laser process. We will explore with them future commercial potential for use of our technology in their product offering.

Governmental bodies such as the Department of Energy & Climate Change would find positive results from this project particularly interesting as one of the Committee on Climate Change's recommendations to the UK in their 2013 'Reducing the UK's carbon footprint' report was to explore more extensive use of CdTe PV. Efficient, cheap PV, as ultimately proposed by this project would be a highly beneficial investment for the UK over the next 10-20 years, as part of their developing renewable energy grid initiatives.

The project proposes a PV technology that has the potential to form the core of many domestic solar panel installations, particularly in light of the opportunity for high efficiency, lightweight, flexible panels which could potentially be cheaper than current rigid alternatives. In this respect, uptake of PV, providing there is a successful market deployment strategy, could be substantial by previously undecided potential buyers. An increase in domestic and commercial PV installations would dramatically decrease reliance on fossil derived energy, and improve local and national resilience to short and long-term energy supply shortages. In addition, reducing the financial payback period will make investment in systems easier, and provide additional financial reward to adopters of this technology.

Our proposed kick-start of the UK CdTe PV market, has the potential for the creation of a number of high quality, high skilled jobs across a number of sectors (e.g. manufacturing, retail, civil engineering) supporting both individual and national economies. With the cost of investing in PV cheaper through our proposed technology, one of the major barriers for market penetration will be lifted and we therefore anticipate substantial market growth of CdTe PV, not just in the UK, but potentially worldwide.