Research Article

Roof-mounted photovoltaic generator temperatue modeling based on common brazil roofing materials

¹ GREEN Solar-IPUC, PPGEM, Graduate Programme of Mechanical Engineering, Pontifícia Universidade Católica de Minas Gerais (PUCMinas), Belo Horizonte, Brazil
² Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brasil
³ University of Colorado Boulder, RASEI, Boulder, Colorado, USA

^* e-mail: asacd@pucminas.br

Received: 10 July 2021
Received in final form: 5 November 2021
Accepted: 6 November 2021

Abstract

This paper examines the performance of solar photovoltaic generators on roofs of residential buildings. The primary focus is the loss of performance due to temperature increase as function of roof material and the distance from the photovoltaic (PV) generator to the roof. A heat transfer model has been developed to predict PV module temperature, and the equations of the model were solved using the Engineering Equation Solver (EES) software. The research modeling correlates the distance of the solar generator to the roof and the roofing material with the temperature variations in the PV generator. There are many models to predict PV module temperature, but this study refines the prediction by the distance from PV module to roof and the roofing material as variables. Optimal combinations of distance and materials that minimize the heating loss in the solar generator leading to increased electrical power generation. Results show an average error of 3%–4% from the temperature predicted by the model to the temperature measured under experimental conditions in Belo Horizonte, Brazil. The minimum roof-module separation required to ensure minimal PV performance loss from heating from the roof is ∼10 cm for red ceramic and cement fiber roofs. For galvanized steel, the optimal distance is between 20 cm and 30 cm. Cement fiber shows the best predicted and measured characteristics for PV-panel roof mounting among the 3-common commercial roofs evaluated in these studies. These investigations were based on roof installations and local materials in Belo Horizonte, Brazil.