High Speed, Energy Efficient Manufacturing of Cadmium Telluride Solar Cells

Lead Research Organisation: Loughborough University
Department Name: Wolfson Sch of Mech, Elec & Manufac Eng

Abstract

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.

Planned Impact

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.
 
Description The use of laser light can significantly modify the the thin material used in modern solar panels to provide an overall benefit to the function solar panel. An 808 nm diode laser has been used to process thin films of CdTe in both CdCl2 and MgCl environments and the surface properties studied. The process appears to be faster and more accurate than current manufacturing processes.
Exploitation Route As this is a feasibility study, it is intended that the outputs of this research will feed into a follow-on project that will seek to develop the technology up to the industrial scale. Ultimately, photovoltaic manufacturers will be able to use this technology to manufacture high performance solar panels faster and more energy efficiently and cheaply than by existing methods. The proposed technology will also be more resilient to future energy black-outs and brown-outs.
Sectors Energy,Environment,Manufacturing, including Industrial Biotechology

 
Description UK-China Low Carbon Manufacturing
Amount £1,600,000 (GBP)
Funding ID EP/S018190/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 03/2019 
End 02/2022
 
Title Heat conduction model for asymmetric, customised laser beams 
Description This was a computer model used for the simulation of laser material interactions in the CdTe laser annealing process. The novelty of this model was that it allowed the modelling of non-uniform optimised laser beams, such as those generated using holograms. 
Type Of Material Computer model/algorithm 
Provided To Others? No  
Impact This model allows the effects of laser beam thermal profiles to be predicted in simulation and then the optimised beam can be created with holographic optics to be used in reality. 
 
Description Careers Day talk on solar technologies at Worksop College 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Engaged with circa 80 students. Discussed academic job role and specific research area (Manufacture of solar panels) which sparked many questions from pupils regarding different renewable energy technologies, suitability of solar for future energy supplies and also on the specifics of being an academic.
Year(s) Of Engagement Activity 2015
 
Description Invited Talk for NECEM Seminar Series 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact Invited talk for seminar series. Presented work on laser annealing of thin film photovoltaics.
Year(s) Of Engagement Activity 2019
URL https://research.ncl.ac.uk/media/sites/researchwebsites/necem/NECEM%20Seminar%20flyer%20Elliot%20Woo...
 
Description Research case study for Advanced Manufacturing Processes and Technology module 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Undergraduate students
Results and Impact Use of the the details of the research project to support learning regarding laser processing for manufacturing.
Year(s) Of Engagement Activity 2017