Influences on the energy delivery of thin film photovoltaic modules

The energy yield delivered by different types of photovoltaic device is a key consideration in the selection of appropriate technologies for cheap photovoltaic electricity. The different technologies currently on the market, each have certain strengths and weaknesses when it comes to operating in different environments. There is a plethora of comparative tests on-going with sometimes contradictory results. This paper investigates device behaviour of contrasting thin film technologies, specifically a-Si and CIGS derivatives, and places this analysis into context with results reported by others. Specific consideration is given to the accuracy of module inter-comparisons, as most outdoor monitoring at this scale is conducted to compare devices against one another. It is shown that there are five main contributors to differences in energy delivery and the magnitude of these depends on the environments in which the devices are operated. The paper shows that two effects, typically not considered in inter-comparisons, dominate the reported energy delivery. Environmental influences such as light intensity, spectrum and operating temperature introduce performance variations typically in the range of 2–7% in the course of a year. However, most comparative tests are carried out only for short periods of time, in the order of months. Here, the power rating is a key factor and adds uncertainty for new technologies such as thin films often in the range of 10–15%. This dominates inter-comparisons looking at as-new, first-year energy yields, yet considering the life-time energy yield it is found that ageing causes up to 25% variation between different devices. The durability of devices and performance-maintenance is thus the most significant factor affecting energy delivery, a major determinant of electricity cost. The discussion is based on long-term measurements carried out in Loughborough, UK by the Centre for Renewable Energy Systems Technology (CREST) at Loughborough University

Influences on the energy delivery of thin film photovoltaic modules

The energy yield delivered by different types of photovoltaic device is a key consideration in the selection of appropriate technologies for cheap photovoltaic electricity. The different technologies currently on the market, each have certain strengths and weaknesses when it comes to operating in different environments. There is a plethora of comparative tests on-going with sometimes contradictory results. This paper investigates device behaviour of contrasting thin film technologies, specifically a-Si and CIGS derivatives, and places this analysis into context with results reported by others. Specific consideration is given to the accuracy of module inter-comparisons, as most outdoor monitoring at this scale is conducted to compare devices against one another. It is shown that there are five main contributors to differences in energy delivery and the magnitude of these depends on the environments in which the devices are operated. The paper shows that two effects, typically not considered in inter-comparisons, dominate the reported energy delivery. Environmental influences such as light intensity, spectrum and operating temperature introduce performance variations typically in the range of 2–7% in the course of a year. However, most comparative tests are carried out only for short periods of time, in the order of months. Here, the power rating is a key factor and adds uncertainty for new technologies such as thin films often in the range of 10–15%. This dominates inter-comparisons looking at as-new, first-year energy yields, yet considering the life-time energy yield it is found that ageing causes up to 25% variation between different devices. The durability of devices and performance-maintenance is thus the most significant factor affecting energy delivery, a major determinant of electricity cost. The discussion is based on long-term measurements carried out in Loughborough, UK by the Centre for Renewable Energy Systems Technology (CREST) at Loughborough University

Educating the world: a remote experiment in photovoltaics

The increasing deployment of photovoltaic (PV) systems requires large numbers of skilled engineers with a greater understanding of all aspects of PV teehnology both theoretical and practical. Developing experimental rigs at universities is expensive and limited to students physically attending the university. One recent approach to increase access to laboratories is the development of remote experiments. Here students can control real experimental equipment using a visual interface via the Internet. In this paper we explore the development of a photovoltaic laboratory to enable users to access and remotely control experimental equipment based at Loughborough University, UK, from anywhere in the world

The development of a photovoltaic remotely operated laboratory experiment: a contribution to meeting the challenge of the renewable energy skills shortage

Skills shortages are often quoted as a threat to renewables growth. The increasing deployment of photovoltaic (PV) systems around the world requires large numbers of trained engineers with a greater understanding of all aspects of PV technology both theoretical and practical. The development of experimental rigs at universities and training establishments is expensive and limited to students physically being present for time constrained activities. One recent approach to increase access to laboratories is the development of remote experiments. Here students can control real experimental equipment using a graphical user interface via the Internet. In this paper we explore the development of a PV laboratory that characterises PV panels under different environmental conditions. It enables users to access and remotely control experimental equipment based at Loughborough University, UK, from anywhere in the world via an Internet connection. We report on student experiences using the laboratory from distance

The development of a remote laboratory for distance learning at Loughborough University

The increasing deployment of photovoltaic systems requires large numbers of skilled engineers with a greater understanding of all aspects of PV technology both theoretical and practical. Developing experimental rigs at universities is expensive and limited to students physically attending the university. One recent approach to increase access to laboratories is the development of remote experiments. Here students can control real experimental equipment using a visual interface via the Internet. In this paper we explore the development of a photovoltaic laboratory to enable users to access and remotely control experimental equipment based at Loughborough University from anywhere in the world

The development of a remote laboratory for distance learning and its impact on student learning

Currently, there is an increase drive in the development of remote laboratories to compliment and sometimes replace physical and virtual laboratories. This drive is fuelled by the impact on the pedagogy of distance learning caused by the rapid advancements in information and communication technologies, especially the internet. In this paper we outline the systematic approach used in the development of the Photovoltaic Remote Laboratory at Loughborough University, highlighting challenges and successes. We also evaluate the impact the remote lab has on student learning to contribute to the growing debat

Student experiences with a remote laboratory and the potential for capacity building in developing countries

Student experiences with a remote laboratory and the potential for capacity building in developing countrie

Accuracy of energy prediction methodologies

In the current market, the specific annual energy yield (kWh/kWp) of a PV system is gaining in importance due to its direct link to the financial returns for possible investors who typically demand an accuracy of 5% in this prediction. This paper focuses on the energy prediction of photovoltaic modules themselves, as there have been significant advances achieved with module technologies which affect the device physics in a way that might force the revisiting of device modelling. The paper reports the results of a round robin based evaluation of European modelling methodologies. The results indicate that the error in predicting energy yield for the same module at different locations was within 5% for most of the methodologies. However, this error increased significantly if the nominal nameplate rating is used in the characterization stage. For similar modules at the same location the uncertainties were much larger due to module-module variations

Accuracy of Energy Prediction Methodologies

In the current market, the specific annual energy yield (kWh/kWp) of a PV system is gaining in importance due to its direct link to the financial returns for possible investors who typically demand an accuracy of 5% in this prediction. This paper focuses on the energy prediction of photovoltaic modules themselves, as there have been significant advances achieved with module technologies which affect the device physics in a way that might force the revisiting of device modelling. The paper reports the results of a round robin based evaluation of European modelling methodologies. The results indicate that the error in predicting energy yield for the same module at different locations was within 5% for most of the methodologies. However, this error increased significantly if the nominal nameplate rating is used in the characterization stage. For similar modules at the same location the uncertainties were much larger due to module-module variations

Comparison of in-person and virtual labs/tutorials for engineering students using blended learning principles

The paper compares the effectiveness of in-person and virtual engineering laboratory sessions. The in-person and virtual laboratory sessions reported here comprise six experiments combined with short tutorials. The virtual lab combined enquiry-based learning and gamification principles. The integration of the virtual labs with in-person teaching created a blended learning environment. The effectiveness of this approach was assessed based on (i) the student feedback (i.e., a questionnaire with open-ended questions and Likert scale feedback), (ii) the students’ engagement with the virtual lab, and (iii) the impact on the academic performance (i.e., class test results). The students reported greater confidence in the understanding of theory in the virtual lab than the in-person lab. This is interesting given that the instruction for the virtual lab and the in-person lab of one experiment is identical (i.e., same instructor, same enquiry-based learning techniques, and same explanations). The students also appreciated the ability to complete the virtual lab anytime, anywhere, for as long as they needed, and highlighted the benefits of the interactivity. The median class test scores of the students who completed some or all the virtual lab experiments was higher than those who did not (83–89% vs. 67%)