# Impacts of Lightning-Induced Overvoltage on a Hybrid Solar PV-Battery Energy Storage System
## 1 Introduction  
Malaysia has various energy resources from conventional sources, such as oil, natural gas, and coal, in addition to renewable energy resources, such as solar photovoltaic (PV) energy, hydropower, wind, and biomass. Currently, about 90% of electricity is generated from conventional resources, especially in Peninsular Malaysia. Therefore, conventionalresources are gradually depleted, which is becoming a big concern for Malaysia and will require overcoming the nation's overzealous reliance on conventional resources. To overcome this problem, there is a need to balance the usage of both conventional and renewable energy resources. Therefore, the Malaysian government has introduced certain policies; the earliest was the Renewable Energy Act 2011, which introduced the Feed-In Tariff (FiT) system [1]. In order to make an industry of renewable energy sources more effective and profitable, the Net Energy Metering (NEM) scheme was launched by the Energy Commission and Sustainable Energy Development Authority (SEDA) Malaysia in 2016. Both of these schemes have the same objective, which is to allow any private individual or organization to generate electricity by using solar PV systems, since Malaysia is the third-largest producer of solar PV energy in the world. The Malaysian government has also planned a ten-year master plan, known as Malaysia Electricity Supply Industry 2.0 [2], which will benefit consumers in the long term by lowering the cost of production, resulting in lower tariffs [3]. Figure 1 shows that Malaysia has abundant levels of solar radiation, receiving about 6 h of sunlight per day.  
Hybrid solar PV-battery energy storage systems are usually installed in outdoor areas, whereby the likelihood of lightning strikes is very high, especially in the areas that are vulnerable to lightning. For instance, Malaysia is recognized as the \"Crown of Lightning\", experiencing an average of 200 thunderstorm days every year [5,6].  
Based on statistical data concerning the cause of typical damage to solar PV systems in South Africa, about 31.2% of the damage is due to lightning strikes [7]. Likewise, similar issues will be expected to occur in Malaysia due to the fact that its geographical location is close to the equator. As reported in [8, 9, 10, 11], both direct and indirect lightning strikes can severely affect solar PV systems that incorporate battery energy storage; in Malaysia, such systems are not properly protected against lightning strikes [11].  
Therefore, the objective of this research is to study the impacts of lightning-induced overvoltage on hybrid solar PV-battery energy storage systems and to provide an overview of the significance of such a system being struck by lightning. When such a system is required to operate in grid-connected mode, this might cause problems, as there is no specific or relevant standard guideline for when lightning-induced overvoltage occurs especially for hybrid solar PV-battery energy storage systems. Furthermore, based on the findings of this study, the selection of protection systems, placements, and ratings of surge protection devices (SPDs) can be discussed further in future studies.  
Throughout this study, essential information on the effects of lightning-induced overvoltage on hybrid solar PV-battery energy storage systems is provided by conducting simulations of different lightning current amplitudes and lightning strike locations using Electro-Magnetic Transient Program--Restructured Version (EMTP-RV) software. By carrying out this study, we hope to provide ideas for an appropriate protection scheme to and suggest how it should be installed.  
Figure 1: Irradiation (yearly average value) in Malaysia. [4].