High-power, low-weight, flexible thin film photovoltaics for space application

Lead Research Organisation: Glyndwr University
Department Name: Science Research Centre

Abstract

The UK has a world class reputation for design and manufacture of space based technologies. A new National Space Academy has been launched this year to help boost the size and quality of the UK's science and engineering expertise. The proposal supports strongly The UK Space Directory, an organisation of eight groups representing and supporting the UK space community and including the Technology Strategy Board that state "the UK Space Industry has come together to propose an ambitious 20 year strategy to capture 10% of the global space market, £40 billion, by 2030 and in doing so create 100,000 UK jobs". The UK houses some of the leading companies in space applications such as; Inmarsat, Rolls Royce, Logica, Vega Space, Astrium, Qioptiq Space Technology and Surrey Satellite Technology Limited. The latter two companies strongly back the research detailed within this proposal and have both provided satements of support.

This proposal seeks to offer an alternative PV technology for large area arrays and to be the first to report thin film cadmium telluride (CdTe) deposited directly onto toughened cerium-doped microsheet glass (CMG), explicitly targeting a significant increase in specific power by a step-change reduction of system weight. The Qioptiq Space Technology CMG microsheet glass is optimised to match the coefficient of thermal expansion (CTE) of gallium arsenide (GaAs) based space solar cells. With the CdTe CTE almost identical to that of GaAs the choice of CMG is ideal for the prevention of delamination under the severe thermal gradients to which space PV is exposed. This adventurous approach, using the CMG as both the radiation barrier and substrate, will be proven by characterisation of 5 x 5 cm2 deposited devices and finally scaled to 10 x 20 cm2 on the Centre for Solar Energy Research (CSER) pilot metalorganic chemical vapour deposition (MOCVD) system.

This proposal has the content and vision to make a significant contribution to the UK's flourishin space industry. Key to the success of the project will be the dissemination and pathways to impact of the research outcomes; this will be ensured through regular reporting to and feedback from a steering group of potential exploiters-Industrial experts and through targeted press releases. This proposal offers UK research the chance to impact the space PV market either through licencing of the arising IP and more excitingly in the current economic climate through manufacture of the final product.

Planned Impact

This proposal has the content and vision to make a significant contribution to the UK's flourishing space industry. Key to the success of the project will be the dissemination and pathways to impact of the research outcomes; this will be ensured through regular reporting to and feedback from a steering group of potential exploiters-Industrial experts and through targeted press releases. This proposal offers UK research the chance to impact the space PV market either through licencing of the arising IP and more excitingly in the current economic climate through manufacture of the final product.

The cost of PV for space deployment is now of significant importance, evidenced by the theme for this year's Space Power Workshop, California being "Maintaining Excellence in Space Power in a Cost-Constrained Environment". The future for space exploration and exploitation offers exciting opportunities for such an alternative, cost-effective solution as flexible thin film CdTe PV. Its potential higher specific power and significantly reduced cost of production fit well with firstly; large arrays for either in space or prospective lunar and Martian bases. Secondly, solar electric propulsion (SEP) in space which is deemed essential for future human exploration missions to deep space. Finally, space qualified CdTe PV addresses the concept of space-based solar power (SBSP), a method of collecting solar power in space for use on Earth. NASA expects this concept to be a reality within the next 10 to 50 years and support of this proposal would position the UK well to play a lead role thus generating high-tech jobs and economic growth.

Publications

10 25 50
 
Description Thin film solar cells have been deposited for the first time onto space qualified ultra-thin (100 micron) cover glass. During this research project the solar cell efficiency has been increased from 7% to over 15% AM1.5 and 13% under the space AM0 conditions. Based on these results it has been possible to predict a world beating power to weight ratio for space durable solar cells of over 0.6 kW/kg.

With our partners at the University of Surrey these solar cells have been put through a rigorous set of mechanical, thermal and radiation tests. These thin film solar cells have been demonstrated to be very robust with no degradation under 10 cycles of thermal shock testing (-200C to +80 C). Mechanical bend and pull tests have similarly shown excellent adhesion of the films and in general failure only occurring when the glass substrate fails.

Radiation testing using 500 MeV protons from the unprotected solar cell side have shown better radiation hardness than previously reported radiation tests on thin film PV and a thousand times the radiation hardness of the multi-junction solar cells normally used for powering satellites. Furthermore, under the very high dose of 1E14 cm-2 where the efficiency decreased to 90% of its initial performance, it was possible to recover to 90% through annealing under conditions experienced in Earth orbit. This raises the prospect that these very robust thin film solar cells could be self healing.
Exploitation Route The results of this research grant are likely to be taken forward through the following:
1. By researchers working on space deployment and in particular deployment of flexible PV arrays.
2. Utra-light weight PV for other applications such as Unmanned Arial Vehicles (UAVs) and for terrestrial applications such as coating industrial roofs with light weight PV.
3. Understanding fundamental properties of thin film structures under harsh conditions.
4. Fundamental mechanisms of radiation damage and recovery in thin film PV.
Sectors Aerospace, Defence and Marine,Construction,Electronics,Energy,Manufacturing, including Industrial Biotechology

URL http://cser.org.uk/space-solar-cells/space-solar-cells/
 
Description Prior to this research project the prospects for using thin film PV in space by ESA were poor to non-existent. The reason for this was previous work carried out in the Netherlands which showed that the thin film PV being investigated would de-laminate in the harsh environment of space. The approach taken in this research has been to deposit the solar cell structure straight onto space qualified protective cover-glass. This cover-glass also matches the thermal expansion coefficient of the thin film PV structure which minimises strain under thermal shock. The mechanical, thermal and radiation robustness of this new solar cell structure have been remarkable and one of our industrial partners, Surrey Satellite Technology Limited (SSTL) is now lobbying ESA to take a fresh look at thin film PV for space. The impressive early results in both PV performance and robustness have led to the research team being selected to provide a thin film PV payload for the UKSA Al-Sat Nano mission due to be launched in 2016. This will be the first flight test of thin film PV directly onto space qualified cover glass and will provide valuable space heritage and evidence for the robustness of these cells. The thin film CdTe solar cell demonstrators on the AlSat-Nano satellite have now been performing well for over a year (launched September 2016) and is still sending back data on current-voltage characteristics of the cells. This is a world first for CdTe thin film solar cells and is all the more impressive as the cells are deposited directly onto ultra-thin glass which was the objective of the research project. The results were presented in a paper at the 68th International Astronautical Congress (IAC), Adelaide, Australia, 25-29 September 2017 (Development of Thin-Film Solar Cell (TFSC) Technology for Space: Flight Results from the AlSat-1N TFSC Payload, Craig Underwood, Dan Lamb, Stuart Irvine, Mark Baker, Alex Dyer, Richard Duke, Brian Stewart, Ben Taylor, Chiara Massimiani, Simon Fellowes, Andrew Clayton, Giray Kartopu, Vincent Barrioz, Rossana Grilli, James Hall, Richard Kimber).
First Year Of Impact 2017
Sector Aerospace, Defence and Marine,Electronics,Energy
Impact Types Economic

 
Description AlSat-Nano satelite payload 
Organisation University of Surrey
Department Advanced Technology Institute (ATI)
Country United Kingdom 
Sector Academic/University 
PI Contribution We provided encapsulated thin film solar cells, that resulted from the EPSRC grant, for inclusion by the Surrey Space Centre as a test payload on the AlSat Nano satellite. The encapsulate cells (on ultra-thin glass) had to be sufficiently robust to survive launch into a low Earth orbit.
Collaborator Contribution The Surrey Space Centre provided the test electronics to measure the solar cell performance and to communicate the data with the spacecraft communications link. They also carried out final tests on the module and integrated it onto one of the faces of the satellite. Since the successful launch in September 2016, We have been working collaboratively with our partners in surrey to download data and provide interpretation of the performance of the solar cells.
Impact A paper has been accepted for oral presentation at the PVSAT 13 conference in Bangor, April 2017 http://www.pvsat.org.uk/ and a journal paper is in preparation.
Start Year 2016
 
Description Advanced Engineering (NEC, Birmingham) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact A talk given by Dan Lamb on "Lightweight Solar Cells for Space and UAV's Applications" was presented to a mixed audience from industry and universities to seek wider industry engagement.
Year(s) Of Engagement Activity 2016
 
Description BBC Wales online, December 26th 2016 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact This was a follow-up from two radio interviews that Professor Irvine and Dr lamb participated with in 2013 and October 2016 (Science Cafe). The title of the article is Swansea solar technology could power moon bases
Year(s) Of Engagement Activity 2016
URL http://www.bbc.co.uk/news/uk-wales-38302609
 
Description British Science Festival (Swansea) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Dr Dan Lamb gave an invited talk, based on the EPSRC research project, with the title: 3. "Solar Cells in Space" that generated a lot of questions and interest from a mixed audience from the general public.
Year(s) Of Engagement Activity 2016
URL http://www.swansea.ac.uk/british-science-festival-2016/
 
Description CDT-TCO Workshop (Liverpool) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact Dr Dan Lamb gave 2 talks to a group of PhD students on the the research outcomes of the EPSRC grant. The main purpose was educational and to inform the research students of the materials challenges for solar cells in space.
Year(s) Of Engagement Activity 2016
 
Description E-MRS Fall meeting (Warsaw, Poland) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Professor Stuart Irvine gave an invited talk entitled "Ultra-thin glass: the ideal superstrate for thin film PV?" that generated a lot of interest from the audience and led to some collaborative research with the Professor Ravi Silva's group at the Advanced Technology Institute, University of Surrey on the application of ultra-thin glass to OPV solar cells.
Year(s) Of Engagement Activity 2016
 
Description PVSAT 12 Conference (Liverpool) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Dr Dan Lamb gave a talk on "Preparation of CdTe PV on Ultra-thin Space Cover Glass for Flight Testing on the AlSat-Nano Satellite Mission" at this annual PV science and technology conference covering professionals across the PV industry and PV research. This talk opened up the possibilities for the application of thin film PV in space and generated extensive interest.
Year(s) Of Engagement Activity 2016
 
Description The 58th London International Youth Science Forum (Imperial College London) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Schools
Results and Impact Dr Dan Lamb gave an invited talk entitled: "Solar Cells and Their Applications in Space" to an international audience of school students. The audience response was very enthusiastic with many questions and a lot of interest shown in the subject.
Year(s) Of Engagement Activity 2016