On the investigation of photovoltaic output power reduction due to dust accumulation and weather conditions Makbul A.M. Ramli a, * , Eka Prasetyono b , Ragil W. Wicaksana b , Novie A. Windarko b , Khaled Sedraoui a , Yusuf A. Al-Turki a a Department of Electrical and Computer Engineering, King Abdulaziz University, Jeddah 21589, Saudi Arabia b Department of Electrical Engineering, Politeknik Elektronika Negeri Surabaya, Surabaya 60111, Indonesia article info Article history: Received 5 April 2016 Received in revised form 21 June 2016 Accepted 25 July 2016 Keywords: Solar energy Photovoltaic Monitoring Power output reduction Dust accumulation Weather conditions abstract Certain environmental conditions such as accumulation of dust and change in weather conditions affect the amount of solar radiation received by photovoltaic (PV) panel surfaces and thus have a significant effect on panel efficiency. This study conducted an experimental investigation in Surabaya, Indonesia, on the effect of these factors on output PV power reduction from the surface of a PV module. The module was exposed to outside weather conditions and connected to a measurement system developed using a rule-based model to identify different environmental conditions. The rule-based model, a clear sky solar irradiance model that included solar position, and a PV temperature model were then used to estimate the PV output power, and tests were also conducted using an ARM Cortex-M4 microcontroller STM32F407 as a standalone digital controller equipped with voltage, current, temperature, and humidity sensors to measure real time PV output power. In this system, humidity was monitored to identify dusty, cloudy, and rainy conditions. Validated test results demonstrate that the prediction error of PV power output based on the model is 3.6% compared to field measurements under clean surface conditions. The effects of dust accumulation and weather conditions on PV panel power output were then analyzed after one to four weeks of exposure. Results revealed that two weeks of dust accumulation caused a PV power output reduction of 10.8% in an average relative humidity of 52.24%. Results of the experiment under rainy conditions revealed a decrease in PV output power of more than 40% in average relative humidity of 76.32%, and a decrease in output power during cloudy conditions of more than 45% in an average relative humidity of 60.45% was observed. This study reveals that local environmental conditions, i.e., dust, rain, and partial cloud, significantly reduce PV power output. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Global developments in the use of solar energy have increased over the last decade. However, although the generation of power using solar PV modules is a major renewable energy source, the amount of power output is greatly influenced by environmental conditions such as solar radiation, wind speed and direction, ambient temperature, humidity, and atmospheric dust. In solar PV applications, the total amount of solar radiation received by the surface of a PV module essentially depends on its orientation and local climate conditions, and although the maximum power point tracking (MPPT) algorithm is applied to determine the maximum power output from a PV module, it is unable to operate adequately if dust is deposited on the surface of the PV module [1,2]. Two studies were conducted to investigate the effects of accu- mulation and physical properties of dust on the performance of PV cells. In the first study, an experimental investigation of the dust accumulation effect on the fill factor, output power, and short cir- cuit current of PV cells was conducted using known materials that were uniformly spread over the PV cells; results showed that the PV cells deteriorated significantly due to the accumulation of dust. In the second study, experimental investigations were conducted using five different physical properties of dust; results showed that finer particles caused greater deterioration in the performance of PV cells than coarser particles. Both studies were conducted using a solar simulator as the source of light and provide experimental evidence of performance deterioration in relation to the * Corresponding author. E-mail addresses: mramli@kau.edu.sa (M.A.M. Ramli), eka@pens.ac.id (E. Prasetyono). Contents lists available at ScienceDirect Renewable Energy journal homepage: www.elsevier.com/locate/renene http://dx.doi.org/10.1016/j.renene.2016.07.063 0960-1481/© 2016 Elsevier Ltd. All rights reserved. Renewable Energy 99 (2016) 836e844