A solar water heater (SWH) converts solar radiation into thermal energy for various purposes, and its technology has experienced numerous developments. Many studies have focused on developing, optimizing, and analyzing the technological configurations of SWH to improve its thermal efficiency, but they rarely achieve 80% efficiency. This review aims to provide a broad overview of SWH, including the energetic and exergetic approaches and analyses, technological development, and examines advantages, disadvantages, and further developments. Various collectors of the SWH and related studies are also highlighted, and the results identify the technical and policy challenges of the implementation. Suggested potential solutions to these challenges are presented with further directions. Furthermore, this study also discusses the limitations of the current SWH technology by presenting the specifications and characteristics. It also presents the mathematical equation model often used, the technology potential, and the results of the latest studies and developments regarding SWH technology. The prospects for further development of the most promising SWH should be analyzed.

Energy is one of the essential human needs that plays a crucial role in achieving sustainable development. Indonesia is among the countries that are highly focused on developing renewable energy to reduce greenhouse gas emissions and achieve net-zero emissions. In addition, the government has launched various policies and programs to promote the use of renewable energy, such as increased investment in biomass, geothermal, and solar power generation. Wind energy stands out as a sufficient, widely available, and an environmentally friendly alternative in renewable energy. In 2021, the Indonesian Energy Outlook highlights that Indonesia has an energy potential of 154.9 gigawatts (GWs). It is associated with minimal emissions of greenhouse gases during its operation and does not demand vast tracts of land. However, the actual installed capacity of wind power plants is at a modest 157.41 megawatts (MWs). Meanwhile, the targeted capacity is 255 MWs for 2025. One significant factor contributing to this lower-than-expected capacity is a lack of in-depth research into the potential of wind energy. Consequently, the primary aim of this paper is to conduct a thorough examination of the wind energy potential in Indonesia. This includes an analysis of the current state of both existing and upcoming power plants, as well as a review of recent studies conducted by Indonesian researchers on wind turbines. Furthermore, this paper explores the government program to encourage the sustainable development of wind power plants. It also explains various aspects including the untapped wind energy potential, the interference in developing wind power plants, and the strategy to harness the full potential of abundant renewable resources in Indonesia. Through an in-depth investigation of the potential of wind energy, this review aims to provide a more comprehensive understanding of the current conditions and prospects of wind power plants in Indonesia as well as contribute to a more accurate mapping of wind energy potential and more targeted development, specifically in remote areas, outer islands, and borders. The results obtained are expected to support Indonesia’s energy transition toward more environmentally friendly and sustainable renewable energy sources, thereby reducing dependence on fossil fuels.

Every country is faced with the problem of limited fossil fuels hence the need for renewable energy sources as alternative solutions to this problem. Among the numerous types of renewable energy, solar can produce 834.1 GW of energy, the highest in the world. It can be used as a heater by utilizing a solar collector, which is part of the Solar Water Heater (SWH). Therefore, this research aims to examine the performance of the SWH type trickle by determining the total efficiency with the fluid flow rate of 2, 3, and 4 lpm. The results showed that the total efficiency produced with 4 lpm higher than the 3 and 2 lpm, with an efficiency value of 58.3%, 49.9%, and 49.7%, respectively. The higher the flow rate, the lower the temperature, with a rise in the accumulated heat absorbed by the water hence the total efficiency value produced increases. In conclusion, the higher the total efficiency value, the better the SWH performance.