Abstract
Photovoltaic (PV) panels and thermal collectors are commonly known as mature technologies to capture solar energy. The efficiency of PV cells decreases as operating cell temperature increases. Photovoltaic Thermal Collectors (PVT) offer a way to mitigate this performance reduction by coupling solar cells with a thermal absorber that can actively remove the excess heat from the solar cells to the Heat Transfer Fluid (HTF). In order for PVT collectors to effectively counter the negative effects of increased operating cell temperature, it is fundamental to have an adequate heat transfer from the cells to the HTF. This paper analyzes the operating temperature of the cells in a low concentrating PVT solar collector, by means of both experimental and Computational Fluid Dynamics (CFD) simulation results on the Solarus asymmetric Compound Parabolic Concentrator (CPC) PowerCollector (PC). The PC solar collector features a Compound Parabolic Concentrator (CPC) reflector geometry called the Maximum Reflector Concentration (MaReCo) geometry. This collector is suited for applications such as Domestic Hot Water (DHW). An experimental setup was installed in the outdoor testing laboratory at Gävle University (Sweden) with the ability to measure ambient, cell and HTF temperature, flow rate and solar radiation. The experimental results were validated by means of an in-house developed CFD model. Based on the validated model, the effect of collector tilt angle, HTF, insulation (on the back side of the reflector), receiver material and front glass on the collector performance were considered. The impact of tilt angle is more pronounced on the thermal production than the electrical one. Furthermore, the HTF recirculation with an average temperature of 35.1 °C and 2.2 L/min flow rate showed that the electrical yield can increase by 25%. On the other hand, by using insulation, the thermal yield increases up to 3% when working at a temperature of 23 °C above ambient.
Highlights
IntroductionThe greenhouse gases emissions caused by human activities are contributing to approximately 1 ◦ C of global warming above pre-industrial levels (0.2 ◦ C per decade) [1]
The results showed a decrease in electrical efficiency from 20% at Standard Test Conditions (STC, Solar cell temperature of 25 ◦ C and Solar irradiation of 1000 W/m2 with solar spectrum air mass of 1.5) to 11% and thermal efficiency of 58%
This paper evaluated the potential of the called the Photovoltaic-Thermal (CPVT) collector and measured its electrical and thermal generation
Summary
The greenhouse gases emissions caused by human activities are contributing to approximately 1 ◦ C of global warming above pre-industrial levels (0.2 ◦ C per decade) [1]. Energy production due to burning fossil fuels is the main source for increasing carbon emissions and this segment needs to switch to renewable energy sources, such as solar (both photovoltaic and thermal), water and/or wind, in order to prevent the most disruptive climate change. Energies 2020, 13, x FOR PEER REVIEW. 2020, 13, x FOR PEER REVIEW of 21 22 of.
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