Performance Enhancement of Roof-Mounted Photovoltaic System: Artificial Neural Network Optimization of Ground Coverage Ratio

Ali S Alghamdi

doi:10.3390/en14061537

Abstract

Buildings in hot climate areas are responsible for high energy consumption due to high cooling load requirements which lead to high greenhouse gas emissions. In order to curtail the stress on the national grid and reduce the atmospheric emissions, it is of prime importance that buildings produce their own onsite electrical energy using renewable energy resources. Photovoltaic (PV) technology is the most favorable option to produce onsite electricity in buildings. Installation of PV modules on the roof of the buildings in hot climate areas has a twofold advantage of acting as a shading device for the roof to reduce the cooling energy requirement of the building while producing electricity. A high ground coverage ratio provides more shading, but it decreases the efficiency of the PV system because of self-shading of the PV modules. The aim of this paper was to determine the optimal value of the ground coverage ratio which gives maximum overall performance of the roof-mounted PV system by considering roof surface shading and self-shading of the parallel PV modules. An unsupervised artificial neural network approach was implemented for Net levelized cost of energy (Net-LCOE) optimization. The gradient decent learning rule was used to optimize the network connection weights and the optimal ground coverage ratio was obtained. The proposed optimized roof-mounted PV system was shown to have many distinct performance advantages over a typical ground-mounted PV configuration such as 2.9% better capacity factor, 15.9% more energy yield, 40% high performance ratio, 14.4% less LCOE, and 18.6% shorter payback period. The research work validates that a roof-mounted PV system in a hot climate area is a very useful option to meet the energy demand of buildings.

Highlights

The population in cities is increasing at a rapid rate and people spend most of their time inside the buildings [1]
Several countries in Europe have defined national guidelines to include renewable energy resources in buildings [10] but no proper guidelines or framework has yet been developed in this regard in Saudi Arabia
In order to optimize the ground coverage ratio of a rooftop PV system while taking into account the self-shading of parallel PV arrays and rooftop surface shading, the following methodological approach was adopted

Summary

Introduction

The population in cities is increasing at a rapid rate and people spend most of their time inside the buildings [1]. In order to overcome the high electricity consumption and high GHG emissions of buildings, some countries have introduced building laws to ensure that buildings are energy efficient, emit less GHG, and generate their own onsite electricity [4]. The European Union 2020 directive about building laws says that by 2020, buildings should consume 20% less electricity, emit 20%. The electricity consumption of buildings in the European Union countries is 40% of the total electricity requirements [6] while this share is 80% in Saudi Arabian buildings [7]. Several countries in Europe have defined national guidelines to include renewable energy resources in buildings [10] but no proper guidelines or framework has yet been developed in this regard in Saudi Arabia

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Conclusion