A study of hybrid solar photovoltaic and thermoelectric energy generation in the Lake Victoria environment

Abstract

Renewable power generation has drawn a lot of interest in Kenya in the field of electrical power generation, especially for standalone electricity power supply systems, hence necessitating the in-depth study of the different systems in the renewable energy sector. In particular, solar power generation has attracted immense attention for both standalone isolated grid systems and also for hybrid PV/wind, PV/diesel and grid connect systems. Thermoelectric generation (TEG) is a fairly new technology of electricity generation which has been used in hybrid with Solar PV where the PV waste heat has been used to generate additional power in the TEGs. Using data collected on site a standalone hybrid of solar photovoltaic and thermoelectric (PV+TEG) power plant has been developed capable of generating sufficient electricity to run an autonomous integrated aquaculture system at the Lake Victoria Region of Kenya. During the study, the hybrid PV+TEG generation system has been designed, sized, harmonized and enhanced to run the autonomous aquaculture system. The heat for running the thermoelectric generation system is sourced from the solar PV array waste heat and interfaced using thermal interface materials to improve the overall system efficiency. A 3-tier study has been conducted to evaluate TEG power, voltage, current and temperature distribution and the overall performance of the hybrid system. Medium temperature gradient (10 °C - 100 °C) TEG has been selected and numerical simulations imposed in Simulink using MATLAB R2010b. Bench setups have been fabricated to study the system performance using weather conditions of Nyalenda Kisumu using three types of thermal interface materials.The results obtained confirm that by accurately modelling the TEG and matching its internal resistance to the load and using the right thermal interface materials in the PV-TEG system, PV output could be improved by up to 6.85% and the TEG alone generating an additional 22% of the PV output in a 30kWp system to sustain a combined sanitation and recirculation aquaculture system for wastewater treatment and reuse. It is recommended that future studies on improvement of the TEG figure of merit and better thermal interface materials will make PV-TEG systems more efficient.