The high integration of photovoltaic power plants (PVPPs) has started to affect the operation, stability, and security of utility grids. Thus, many countries have established new requirements for grid integration of solar photovoltaics to address the issues in stability and security of the power grid. In this paper, a comprehensive study of the recent international grid codes requirement concerning the penetration of PVPPs into electrical grids is provided. Firstly, the paper discusses the trends of PVPPs worldwide and the significance of improving grid codes’ requirements. In addition, the comparison of common requirements covered in the majority of international grid codes considers high- and low-voltage ride-through capabilities, voltage and frequency regulation, and active and reactive power support requirements. Finally, a broad discussion on the compliance technology challenges and global harmonization of international grid codes that the PVPPs have to address is presented. The study summarizes the most recent international regulation regarding photovoltaic integration and research findings on the compliance of these regulations and proposed recommendations for future research. It also can assist power system operators to compare their existing requirements with other universal operators or establish their own regulations for the first time. Additionally, this research assists photovoltaic manufacturers and developers to get more accurate understanding from the recent global requirements enforced by the modern grid codes.A large portion of solar power plants are linked to the utility grid, which is well known as the grid-connected photovoltaic (PV) system (GCPS).1 Electricity generation with GCPS has become the trend of modern power systems, and the ensuing impacts on power structures are increasingly more prominent. Therefore, it is important to analyze PV power plants’ (PVPPs) impacts on stability, power quality, and operation of the utility grid as well as the impacts of the utility grid on PV system generators. For this purpose, several new requirements and regulations for the operations of renewable energy sources, especially the PV system, have been provided by different countries. These are known as the new grid code (GC) requirements.2-5These GCs have been traditionally developed to regulate the interconnection of conventional power plants within the network. The technical specification of GCs varies from one country to another based on the characteristics of the national grid.6 In the recent past, the number of renewable energy power plants linked to the grid was at first very low in comparison with traditional energy plants. However, this satiation has changed extensively over the most recent years. For that reason, it has become very important to improve the GCs with regard to the connection of renewable energy power plants as one of the main sources of generation to avoid any problem in network operations. With regard to this, the elaboration of specific stringent technical requirements for wind power plant (WPP) connection as a part of the modern GCs is imposed by some countries worldwide.7, 8 Several studies in the literature focused on evaluating the new rules of GCs concerning the integration of WPP. Over the recent years, many reviews compared and analyzed these GCs all over the world.7-9 However, there are recent studies that compared and evaluated the compliance of GC requirements of WPPs via simulation techniques.10-15 Nevertheless, for PV system integration, especially large-scale PVPPs connected to the transmission or distribution system, GCs are currently improved and revised. However, further investigation is required. Therefore, this study introduces a complete discussion on the trend of PV system worldwide, along with the significance of GC advancement.Like traditional power plants, modern GCs require PVPP contribution to support the grid stability and withstand different grid disturbances and auxiliary service arrangement. The main focus in the GC is fault ride-through (FRT) requirements being either low-voltage ride through (LVRT) or high-voltage ride through (HVRT), injection of reactive current, active power control (APC), and voltage and frequency regulation.5, 6, 16, 17 In the literature, the issues of modern GC requirements concerning the penetration of PVPPs have been explored. The new technical regulation in German GCs imposed by the German Association of Energy and Water Industries concerning PV connection to medium and high voltages is considered as the first regulation worldwide.18, 19 Lately, these requirements are often used as references for other codes. There are a few publications investigating these requirements.16, 20 The Australian GC requirements for PV integration were first presented in 2014 by the Australian Energy Market Commission.21-23 The technical regulations of Japan, China, the United States, Romania, and Spain were studied in previous works.24-28 In 2014, Italy issued a new requirement regarding PV penetration in the modern version of its CEI 0-21 GC.29 In Denmark, individual technical regulation is defined for PVPPs, which are must generate more than 11 kW in compliance.30 In South Africa, on the other hand, the GC specifies technical criteria for PV power stations connected to both the distribution system and transmission system.31 In 2017, Malaysia has issued the requirements of FRT for large-scale PV integration in the national company regulation.32 A comparative research of the international GCs reported previously33 contains only the European countries regulations that are currently available, also considering IEEE 1547 standards34 and European International Electrotechnical Commission 61727 standards.35 A brief comparison study among the GCs of Germany, Italy, the United States, and Australia focuses on the reaction of the PV farm regulation when there are disturbances.17 The German GC compatibility of GCPS under grid faults is presented in a previous work.36 A similar study proposed by Lin Ma et al37 considers the technical requirements of the Chinese GC. The most recent review compared the international GCs’ technical regulation to ensure frequency and voltage stability control with regard to the integration of large-scale PV farms to the power grid was investigated in.38However, as the size and number of GCPS are increased, many countries have begun to enforce advance and extra requirements such as the injection of reactive current control on PVPPs, namely, the LVRT capability to manage reactive power at some stages in a network disturbance, frequency, and power system stabilization.39 These advance regulations were just absorbed in some codes over the recent couple of years. Therefore, an up-to-date comparison of different GCs all over the world may be very useful for grid operators in addition to PV solar manufacturers. This investigation could assist utility grid operators in evaluating their necessities versus other universal operators. It likewise helps new grid operators to begin setting up their special requirements in view of the requirements of leader countries in this field that already have significant positive experience from the operation of large PV energy levels in their power system, including Germany, China, and the United States despite the fact that every country should formulate its technical requirements primarily based on the robustness of their network, PV power system level, and national grid rules. Moreover, the comparison of global GCs will allow PV designer, operators, researchers, and PV system manufacturers to gain a more precise knowledge from the most recent international standards, which thus strengthens their competency within the worldwide PV system market where the expected global revenue by 2024 would be in excess of $1.2 trillion.40The proposed study addresses a complete discussion on today’s status and trend of PVPPs worldwide along with the significance of GC improvement and global harmonization. The GCs compared in this paper are those that are approved by the power system operators of the respective countries to date. Furthermore, an analysis of the main technical requirements in GCs for the GCPS is developed. This analysis is conducted through a comparison of main regulations related to active and reactive power requirements, voltage and frequency control, and dynamic requirements or LVRT during grid faults. Then, the challenges that the PV system operators face and the global harmonization of GC requirements are also discussed. Finally, the paper proposes some recommendations and suggestions for future studies from the perspective of academic research and engineering application.