Economic analysis and environmental impact of flat plate roof mounted solar energy systems

The flat plate solar water heating system and solar photovoltaic (PV) system are two mature technologies available in the commercial market, which can decrease the residential energy requirement substantially. Several research organizations are working on solar PV/T system to make it competitive to solar thermal system and solar PV system. Innovative designs over the decades have improved the performance of the solar PV/T collector significantly. However, the choice of material-of-construction play a vital role in reducing the mass, cost, embodied energy and embodied CO2 emissions of the solar PV/T collector. In this paper, a solar PV/T based water heating system was compared with a solar PV system and a flat plate solar water heating (SWH) system based on economic evaluation and environmental assessment. Results obtained show that due to the higher overall efficiency, the solar PV/T system has better benefit-to-ratio compared to solar PV system, while being competitive to solar thermal system. Also, it makes the best use of the available domestic roof-space, minimizes quantity of construction materials and payback period. Further, the embodied energy and embodied CO2 emission of the PV/T collector is less than the other two solar energy systems combined.