# Benefit Analysis of Grid-Connected Floating Photovoltaic System on the Hydropower Reservoir
## 1 Introduction  
Global warming is the worst thing for the earth in the future, and the use of renewable energy sources is a valuable solution to prevent adverse effects on human life [1]. It is necessary to keep the global temperature increase to a maximum of 1.5 \({}^{\circ}\)C above pre-industrial times [2]. According to 2016 data for Southeast Asian countries, energy demand has increased by 60% in 15 years [3]. Renewable energy targets are set by each country to enhance their respective goals. In the context of the world, every country has a step-by-step plan for limiting and eliminating power sources that use fossil fuel, especially coal-fired power, as well as for setting targets for developing renewable energy instead. The real understanding of solar energy is that it offers the most natural, ubiquitous, sustainable, abundant and clean processes [4; 5; 6]. The global potential of solar energy is thousands of times greater than the current global energy demand [7]. The government of Vietnam has put mechanisms in place in order to encourage investment in and development of renewable energy, of which, solar power is the most prioritized industry because it offers many advantages. Vietnam also previously applied an import tax (FiT) on solar photovoltaic, solid waste, biomass, wind, and small hydroelectricity in 2017. On 6 April 2020, the Prime Minister approved decision 13, for which, the purchase price of electricity from PV plants were listed as follows:  
Floating PV plants have a selling price of 1783 VND/kWp, which is equal to 7.69 UScent/kWp. Solar farm PV plants have a selling price of 1644/kWp VND, which is equal to 7.09 UScent/kWp. Rooftop PV plants have a selling price of 1943 VND/KWp, which is equal to 8.38 UScent/KWp. According to the report on electricity demand in Vietnam at the Mastering Energy Supply for International Isolated Areas conference on 31 March 2022, the Government determined the aim of increasing the total generation and importation electricity capacity from 70,000 MW in 2000 to 146,8000 MW in 2030. Total generation and importation electricity energy is meant to increase from 330 million kWh in 2020 to 695 million kWh in 2030. Currently, Vietnam has produced more than 170 million kWh of electricity from fossil sources and cannot exploit anymore, so it is imperative to shift to renewable energy sources to generate electricity without incurring high electricity production costs as energy demand increases. Vietnam's energy target of \"Zero CO2\" by 2050 was determined by the Prime Minister at COP26. According to the national targets, solar energy will become the main renewable energy source of the country in the future. According to the news from the Electricity of Vietnam (EVN), as of 31 October 2021, the total installed capacity of renewable energy sources reached 20,644 MW, of which, hydroelectricity accounted for 29.6%, solar energy 22.57%, wind energy 5.16%, gas 10%, oil approximately 2%, and biomass 0.28% of the total power capacity. The renewable energy development target for power plant VIII, approved on 1 October 2019, identified the promotion for exploitation and use of effectively renewable energy sources for electricity production, in which, priority is given to distributed solar power for the main purpose of self-use. The variations of energy parameters and economy parameters of the configurations were analyzed based on an economic point of view, and will help to predict and design an optimal hybrid photovoltaic system, cogeneration system, or stand-alone solar power system. Looking at the recent progress results provides a different view of the aspects detailed in several papers, as shown in Table 1.