Performance Enhancement of Building-Integrated Concentrator Photovoltaic System Using Phase Change Materials

Building-integrated Concentrator Photovoltaic (BICPV) technology produces noiseless and pollution free electricity at the point of use. With a potential to contribute immensely to the increasing global need for a sustainable and low carbon energy, the primary challenges such as thermal management of the panels are overwhelming. Although significant progress has been made in the solar cell efficiency increase, the concentrator photovoltaic industry has still to go a long way before it becomes competitive and economically viable. Experiencing great losses in their electrical efficiencies at high temperatures that may eventually lead to permanent degradation over time, affects the market potential severely. With a global PV installed capacity of 303 GW, a nominal 10 °C decrease in their average temperatures could theoretically lead to a 5 % electricity efficiency improvement resulting in 15 GW increase in electricity production worldwide. However, due to a gap in the research knowledge concerning the effectiveness of the available passive thermal regulation techniques both individually and working in tandem, this lucrative potential is yet to be realised. The work presented in this thesis has been focussed on incremental performance improvement of BICPV by developing innovative solutions for passive cooling of the low concentrator based BICPV. Passive cooling approaches are selected as they are generally simpler, more cost-effective and considered more reliable than active cooling. Phase Change Materials (PCM) have been considered as the primary means to achieve this. The design, fabrication and the characterisation of four different types of BIPCV-PCM assemblies are described. The experimental investigations were conducted indoors under the standard test conditions. In general, for all the fabricated and assembled BICPV-PCM systems, the electrical power output showed an increase of 2 %-17 % with the use of PCM depending on the PCM type and irradiance. The occurrence of hot spots due to thermal disequilibrium in the PV has been a cause of high degradation rates for the modules. With the use of PCM, a more uniform temperature within the module could be realised, which has the potential to extend the lifetime of the BICPV in the long-term. Consequentially, this may minimise the intensive energy required for the production of the PV cells and mitigate the associated environmental impacts. Following a parallel secondary approach to the challenge, the design of a micro-finned back plate integrated with a PCM containment has been proposed. This containment was 3D printed to save manufacturing costs and time and for reducing the PCM leakage. An organic PCM dispersed with high thermal conductivity nanomaterial was successfully tested. The cost-benefit analysis indicated that the cost per degree temperature reduction (£/°C) with the sole use of micro-fins was the highest at 1.54, followed by micro-fins + PCM at 0.23 and micro-fins + n-PCM at 0.19. The proposed use of PCM and application of micro-finned surfaces for BICPV heat dissipation in combination with PCM and n-PCM is one the novelties reported in this thesis. In addition, an analytical model for the design of BICPV-PCM system has been presented which is the only existing model to date. The results from the assessment of thermal regulation benefits achieved by introducing micro-finning, PCM and n-PCM into BICPV will provide vital information about their applicability in the future. It may also influence the prospects for how low concentration BICPV systems will be manufactured in the future.The financial support provided jointly by Engineering and Physical Science Research Council, UK (EP/J000345/1 and EP/K03619X/1) and Department of Science and Technology (DST), India is greatly acknowledged