Stability and Performance of Photovoltaics (STAPP)

Lead Research Organisation: Loughborough University
Department Name: Electronic, Electrical & Systems Enginee


Definition of the performance of photovoltaics is normally reduced to the efficiency alone. However, this number contains no indication of key issues such as system component reliability, module stability or appropriate balance of system design -- all of which play a crucial role in determining the performance in terms of usability. The key indicator is the levelised cost of energy (LCOE). The main influences on this, and thus the viability of photovoltaic technologies, are not only in material science but also in the way systems behave in the long term, and the uncertainty in predicting their behaviour. The link between laboratory-based materials science and the LCOE is poorly understood, revealing gaps in scientific knowledge which will be filled by this project. The key outcome is improved understanding of the potential for deploying photovoltaics in different climatic zones. The biggest unknowns in the LCOE are: understanding of the stability and long-term performance of photovoltaic modules; how a holistic system performance can be described; and the uncertainty in life-time energy yield prediction. This is crucial, especially for newer thin film technologies, which have been shown to be more variable in degradation and often suffer inappropriate balance of system components. Close collaboration with manufacturers of thin film as well as crystalline silicon devices will ensure that these aspects are appropriately covered. Novel measurement and modelling approaches for the prediction of life-time energy yield of the modules will be developed and validated against realistic data in collected in different climatic zones. This will result in the development of accelerated test procedures. Uncertainty calculations will enable identification and minimisation of this, and thus reduce the LCOE. A holistic systems approach is taken, specifically looking at the effects of different inverters in different climates and the effects of the existing network infrastructure on energy performance. At the heart of this project is the development of models and their validation, all focused on predicting the lifetime energy yield. A measurement campaign will be undertaken using novel techniques to better monitor the long-term behaviour of modules. Detailed, spatially-resolved techniques will be developed and linked to finite element-based models. This then allows the development of improved accelerated tests to be linked to real environments. These models will be validated against modules measured in a variety of realistic deployments. Using a geographical information system, maps of environmental strains and expected degradation rates per year for the different technologies will be developed.The feedback from the grid is an often underestimated effect on photovoltaic system performance. Typically, the grid and power conditioning cause 5-10% losses in otherwise appropriately installed systems; in unfortunate cases this can rise to 60%. The underlying reasons need to be better understood, so specific models for the interaction with the grid and different control strategies will be developed with the overall aim to minimise these loss effects.This project will be crucial for both the UK and India to translate their ambitious installation plans into reality as it will deliver the tools required to plan the viability of installations via geographical information systems, underpinned by a robust science base. This will aid decisions on the use of appropriate photovoltaic technology for a given site, to include both the modules themselves and other system components, to maximise cost-effectiveness and reliability.

Planned Impact

The outcome of this project will be a vastly improved understanding of how new and existing photovoltaic materials operate at the module and system level under different climatic conditions, represented by the UK and India (but with relevance to many other locations). Since the project focuses on energy yield and the levelised cost of electricity (LCOE), the results will be relevant to all sectors that are involved in the implementation of photovoltaics and the wider issues of energy in general. Nevertheless, we can define five sectors with specific interest in the results of the project, over and above the academic community, as shown below: 1. Companies involved in the manufacture of photovoltaic modules, the design of photovoltaic systems and the installation of photovoltaic systems 2. Organisations involved in the development of energy systems -- especially electricity distribution companies 3. Standards organisations dealing with the PV and electrical sector 4. Government and related organisations involved in the development of energy strategy, including policy decisions 5. Companies offering measurement equipment or service measurements. The project will impact all of the above communities, both in the short- and medium term. Whilst the project does not develop new materials directly, it will enable a deeper understanding of the operation of the newer PV technologies to a lower uncertainty of the energy yield and, therefore, of the LCOE of the systems. This will allow a significant reduction of LCOE through improved financing options; this will have a very significant impact on the PV industry. Reduced LCOE will enable the PV industry to achieve grid parity faster, i.e., reach the point where no further financial subsidies are required. Thus the project will positively impact on the speed of growth of the industry as a whole, and the project partners in particular. Two types of products are developed within the project and appropriate commercialisation partners are within the project. Firstly, there are novel measurement machines such as the measurement of localised QE in thin film multi-junction devices. This is equipment of great use to the PV industry, and by Perkin Elmer working closely with Loughborough University on this aspect, a commercial exploitation route is provided. Secondly, service type measurements will be developed, such as accelerated qualification tests. Among our partners, SEC is offering such tests commercially, in addition to Ipsol Test Ltd. Thus the commercialisation of these products will be ensured, creating employment in both the UK and India. Beyond these obvious commercialisation routes, the project is positioned around development of scientific models and pre-standardisation research. This tends to be difficult to commercialise directly. However, commercialisation of new technologies and progress of the industry would be adversely affected by the lack of such research. The development of accelerated tests and scientific models will allow a faster route to market for new and innovative technologies. The evaluation of novel products will reduce the risk of market introduction and early failure, which in turn increases the likelihood to succeed in today's difficult market. The project will also benefit the academic communities involved, as they can learn from each other. The project will educate a large number of performance specialists (the PDRAs, PGRAs and Research Students), which will enable both the UK and India to support the anticipated growth in installations. The lack of this would hinder progress, as there currently is a dearth of well-trained people in this field. The project will also improve the international standing of all partners involved.


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Description The grant was to identify main reasons for failure in PV systems in India and the UK to support the growing industries in both countries. There have been many discoveries such as:
- models for ageing of PV modules, specifically on the impacts of damp-heat (water uptake of the PV module) on ageing and the stability of the structure
- new tools to characterise PV devices in a non-destructive way
- quality enhancement throughout the metrology of PV modules
- system performance models and associated inputs
Exploitation Route The work goes towards quality enhancement, manufacturing control and system engineering and will reduce the risk in overall installation.
Sectors Chemicals,Construction,Electronics,Energy,Environment,Financial Services, and Management Consultancy,Government, Democracy and Justice

Description The findings have been used to investigate risks associated with PV system operation throughout he entire value chain. Understanding the risks allows a significant reduction in cost of energy as failures and durability are the dominant factors in energy generation costs by PV system performance. The project enabled better modelling and more detailed assessment of generation cost by providing the tools in terms of measurement and modelling to identify key components in this risk assessment. It also helps setting subsidy levels for PV in both countries.
First Year Of Impact 2012
Sector Chemicals,Construction,Electronics,Energy,Financial Services, and Management Consultancy,Government, Democracy and Justice,Manufacturing, including Industrial Biotechology
Impact Types Economic

Description Membership of International Task Force
Geographic Reach Multiple continents/international 
Policy Influence Type Participation in a guidance/advisory committee
Impact We now have more engineers with advanced knowledge to run their energy supply systems
Description Power Network Research
Amount £45,000 (GBP)
Organisation National Grid UK 
Sector Private
Country United Kingdom
Start 09/2010 
End 09/2013
Description UK India Smart Grid and Storage
Amount £980,000 (GBP)
Funding ID EP/K036173/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 02/2014 
End 01/2017
Description Collaboration with IIT Kharagpur in Renewable Energy Integration 
Organisation Indian Institute of Technology Kharagpur
Country India 
Sector Academic/University 
PI Contribution We have developed model of solar PV system that has been used by the researchers in the consortium.
Collaborator Contribution The collaborator developed method of power converter switching which tackled the challenges of interfacing PV inverter.
Impact Joint research publications resulted from this collaboration. Staff exchanges have taken place bilaterally.
Start Year 2009
Description DECC Collaboration (now become BEIS) 
Organisation Department of Energy and Climate Change
Country United Kingdom 
Sector Public 
PI Contribution Impact of UK PV installations on national infrastructure, provision of datasets
Collaborator Contribution advice and insight on current PV market and technological conditions
Impact understanding socio-economic impact of PV installations
Start Year 2013
Title H-bridge based level doubling circuit for cascaded Hbridge multilevel inverters 
Description H-bridge based level doubling circuit for cascaded Hbridge multilevel inverters 
IP Reference Indian Patent Application No.: 0125/KOL/2012 
Protection Patent granted
Year Protection Granted 2012
Licensed No
Impact not known yet
Title System and Method for Detection and Characterization of Delamination in PV Modules 
Description System and Method for Detection and Characterization of Delamination in PV Modules 
IP Reference Indian Patent Application No.: 1424/MUM/2014 
Protection Patent granted
Year Protection Granted 2014
Licensed No
Impact not known yet.
Title SURYA 
Description Software "SURYA" for simulation of large PV arrays in a realistic time frame is developed by M. B. Patil, Gaurav Trivedi and Abhay Chopde (Jointly with IIT Guwahati and VIT Pune) 
Type Of Technology Software 
Year Produced 2014 
Impact not known yet. 
Description Clean Energy Ministerial, Delhi, India 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact The CEM is a global forum to share best practices and promote policies and programs that encourage and facilitate the transition to a global clean energy economy. It took place from16th April to 3pm on 18th April 2013.The Deputy Chairman of India's Planning Commission, Montek Singh Ahluwalia, co-chaired the event with U.S. Energy Secretary Steven Chu. Other ministers confirmed to be in attendance include Minister Greg Barker from the UK's Department of Energy and Climate Change and Ministers from China, Denmark and South Africa.

STAPP project was presented by junior rearchers from the project. A STAPP banner and leaflet were presented at this event.
Year(s) Of Engagement Activity 2013
Description Energy Generation of PV Systems Workshop EGPVS 2013 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact This was a workshop organised by STAPP team at CREST Loughborough Uni. There was a good participation from acedemia and industry. Their feedback was very good hence this has repeated second time with the aim of becoming a recurring event every year.

good feedback received from participants.
Year(s) Of Engagement Activity 2013
Description Spatially-resolved Characterisation of Photovoltaic Devices 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Postgraduate students
Results and Impact Poster presentation, won the 3rd poster pize at the Midlands Energy Graduate School (MEGS).

recognition of good performance and quality of the work
Year(s) Of Engagement Activity 2012