On Differential Temperature Controller Setpoint Selection for Active Photovoltaic-Thermal (PV-T) Systems
Pedro Magalhães 1 * , João Martins 2 3, António Joyce 4
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1 Instituto de Engenharia de Sistemas e de Computadores de Coimbra, Departamento de Engenharia Electrotécnica e de Computadores, Rua Sílvio Lima, Pólo II, Universidade de Coimbra, 3030-290 Coimbra, PORTUGAL
2 Centre of Technology and Systems, UNINOVA, FCT Campus, 2829-516 Caparica, Monte de Caparica, Almada, PORTUGAL
3 Departamento de Engenharia Electrotécnica, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, PORTUGAL
4 Laboratório Nacional de Energia e Geologia, PORTUGAL
* Corresponding Author

Abstract

Active photovoltaic-thermal (PV-T) systems for solar heating and electricity generation are likely to employ the same differential temperature pump controllers as equivalent non-hybrid solar thermal (ST) systems. However, the typical controller setpoint selection methods for cost-effective and stable pump operation fail to consider the effect on photovoltaic (PV) electricity generation taking place in PV-T systems. Analytical relations for the same goals were derived to anticipate this influence using the steady-state Florschuetz PV-T collector model and compared with equivalent numerical methods relying on an extension of the Perers model designed to encompass PV-T collectors, namely by modelling electricity generation and the associated thermal performance reduction. Both methods indicate the minimum turn-on and turn-off setpoints for cost-effective and stable operation increase and decrease, respectively, relative to those for non-hybrid operation of PV-T systems or equivalent non-hybrid systems, and more so at higher irradiance levels, though the variations are shown not to be significant for a range of PV-T systems represented and can be reasoned to be inflated or of limited practical relevance. In conclusion, the effect of pump operation on electricity generation is not predicted to be a determining factor for differential temperature controller setpoint selection in PV-T systems.

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Article Type: Research Article

https://doi.org/10.20897/ejosdr/3926

, 2019 - Volume 3 Issue 1, Article No: em0066

Publication date: 06 Feb 2019

Online publication date: 07 Oct 2018

Article Views: 786

Article Downloads: 686

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