Optimal Orientation and Tilt Angle for Maximizing in-Plane Solar Irradiation for PV Applications in Japan

Cao Yu,Jing Chai,Jianxi Yao,Yong Khoo,Shuwei Han

doi:10.3390/su11072016

Cao Yu, Jing Chai + Show 3 more

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https://doi.org/10.3390/su11072016

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Abstract

To maximize the direct insolation received by flat-plate photovoltaic (PV) modules, the tilt angle is usually the site’s latitude and the modules are oriented towards the equator. However, this may not be the optimal placement, as the local climatic conditions will influence the optimal orientation and tilt angle. Transposition models can be used to simulate the insolation on planes with various tilts and azimuths, using a single set of (horizontal) global and diffuse irradiance measurements. Following this method, five maps including optimal orientations, tilt angles, maximum annual tilted irradiations, percentage improvements of the optimally-tilted PV installation versus the conventional latitude-tilted PV installation, and annual diffuse fraction were plotted over the geographical area of Japan. Spatial patterns in these maps were observed and analyzed. The key contribution of this work is to establish a database of optimal PV installations in Japan. Compared to the conventional rule of thumb of tilting the module at latitude facing south, it is shown that the optimally tilted surface receives up to 2% additional annual solar irradiation.

Highlights

After the Fukushima nuclear disaster in 2011, the Japanese government announced plans to expand the solar photovoltaic (PV) installations to reduce reliance on nuclear power
The optimal orientation and tilt angle for maximizing in-plane solar irradiation in Japan was studied to understand the potential of PV adoption in Japan
The orientation and tilt angle for fixed array installation are critical parameters that affect a photovoltaic (PV) system performance, directly determining the solar radiation received by the PV modules

Summary

Introduction

After the Fukushima nuclear disaster in 2011, the Japanese government announced plans to expand the solar photovoltaic (PV) installations to reduce reliance on nuclear power. The optimal orientation and tilt angle for maximizing in-plane solar irradiation in Japan was studied to understand the potential of PV adoption in Japan. The orientation (azimuthal rotation) and tilt angle for fixed array installation are critical parameters that affect a photovoltaic (PV) system performance, directly determining the solar radiation received by the PV modules. Khoo et al studied the optimal orientation and tilt angle for maximizing in-plane solar irradiation for fixed-tilt PV modules in Singapore [8]. Using the methodology from previous work and the publicly available countrywide weather data in Japan, this paper presents a visual database of optimal orientation and tilt angles in Japan and correlates it to local climatic conditions such as irradiation intensity and diffuse fraction

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