Development of a hybrid solar photovoltaic and heat pump system for domestic heating and electricity generation

  • Mustapha Obalanlege

Student thesis: Doctoral ThesisDoctor of Philosophy


This research investigates a hybrid photovoltaic thermal heat pump system that uses an indirect expansion method. It combines multiple solar photovoltaic thermal panels that convert solar energy to heat and electricity with a water-to-water heat pump. This allows for the generation of heat and electricity on the domestic level from sunlight. The technical feasibility of the system is examined through experimental and mathematical analyses whilst the economic viability of the system is assessed through techno-economic analysis in the UK.

The research also studies the effect of short cycling phenomenon on the performance of a hybrid photovoltaic thermal heat pump system in partial load. The system's response to variations in solar irradiance, water tank volume and the water flow rate through the PVT are analysed. The system is modelled deploying quasi-steady state heat transfer and thermodynamic equations and validated by the experimental data. The analysis takes incremental time steps to solve for the fluid's temperature changes from the heat pump and the solar PVT panels. The model is used to conduct a parametric study of the system with changes in solar irradiance, size of the water tank and the water flow rate in the PVT pipes (laminar and turbulent) on the performance of the system are analysed. The techno-economic analysis of the hybrid system is studied, taking into account the effect of government policy on renewable energy such as the Smart Export Guarantee (SEG) and Renewable Heat Incentive (RHI).

The thesis concludes that the hybrid photovoltaic thermal heat pump system works and is both technically and economically viable in the UK. The research demonstrates that the system is cost competitive with gas and electrical systems both independently and under UK renewable energy policy.
Date of AwardJul 2021
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsNorthern Ireland Department for the Economy & BL Refrigeration Ltd
SupervisorSeyedyaser Mahmoudi Larimi (Supervisor), Roy Douglas (Supervisor) & Marco Geron (Supervisor)


  • solar
  • heat pump
  • hybrid system
  • efficiency
  • photvoltaic themal

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