Increasing human activity has an impact on energy needs. Electrical energy is the most dominant type of energy used daily. the increase in electricity demand in East Java was due to an increase in industrial activity in several cities in East Java, such as Surabaya, Mojokerto, Sidoarjo. Meanwhile, the electrical energy needs of several rural areas in East Java, such as in Bodowoso, Bangkalan, Sumenep have not been fulfilled due to geographical factors. The solution to fulfillment of electricity in rural areas can utilize the potential of alternative energy, such as solar energy and biogas. The high potential of solar energy and biogas can be used as an energy source for solar PV-biogas hybrid power plants. The aim of the study was to study the application of a solar PV-biogas power plant model in rural areas. The research method of the solar PV-biogas hybrid power plant is carried out in several stages to assess the potential for the application of hybrid power plants in rural areas in eastern Java. The research method uses a 100 Wp solar PV hybrid system model and 1 KW biogas generator set by analyzing the potential of electricity produced on average per day. The results of the study of the analysis of the potential application of solar PV-biogas power plants show the configuration of the power plant model of generating solar PV-biogas generators produced by solar PV electric power 1.260 kW per day and 0,379 kW KW biogas generator with a total electrical energy of 1,639 kW / day. Electric energy consumption per family head is an average of 1 kWh / day. the application of a solar PV-biogas hybrid power plant still with a surplus of 0,639 KW. the model of solar PV-biogas generator has a good effective and efficient to be applied in rural Java east.

The utilization of biopolymers for energy applications continues to attract researchers, due to the unique properties of biopolymers that are easily modified, such as cassava starch (CS) biopolymer that has hydroxyl molecular chains. However, the brittle, and non-waterproof nature of starch films is an obstacle to their use in triboelectric nanogenerator (TENG) solid-solid films. This study aims to improve the physicochemical properties of cassava starch films by modifying them into nanocomposite films. The nanocomposite film was made from 70:30 CS/polyvinyl alcohol (PVA) composite and variation of TiO2 nanoparticles addition using solvent casting method. The results showed that the mechanical properties of cassava starch film increased with the addition of PVA. Meanwhile, the addition of TiO2 above 1 wt % of the mechanical properties of the film tends to decrease. The film has low wettability properties with a contact angle of 83.6°. The performance of the nanocomposite film as a Rotary disc freestanding film (RDF-TENG) produces 4.4-fold the output voltage and 2.8-fold the current compared to the film without TiO2. This is a new finding that the CS/PVA-TiO2 nanocomposite film has the potential for TENG films in high-humidity environmental conditions

The use of solar PV as an alternative to fulfill household-scale electricity needs has begun to be widely developed. However, the problem of investment costs and the location of solar PV placement for household scale is still a challenge in its implementation. The construction model of rooftop solar PV can affect the investment cost and performance of solar PV. In this paper, the triangle model of rooftop solar PV on grid with PLN (PT. Perusahaan Listrik Negara) electricity network is studied in terms of technology and economics to determine the feasibility of implementing 900 VA household-scale power plants. Testing the application of solar PV technology under solar radiation conditions in the city of Surabaya, Indonesia as a case study. Calculation of electricity production, energy savings, energy sales, and energy purchases to determine technological feasibility as well Net Present Value (NPV), Benefit Cost Ratio (BCR), and Payback Period (PP) to determine the level of economic feasibility. The results of the research of 1,5 KWP (kilowatt peak) solar PV technology on a household scale are able to meet energy needs and reduce PLN electricity purchases to 0% and can sell electrical energy by 13.96% / year of the total electrical energy produced. In addition, the NPV, BCR with a value greater than zero, and PP of 8.6 is less than 15 years which is the service life of solar PV, so solar PV/ PLN on grid is feasible to be implemented for household scale power generation models.

High humidity environments can accelerate the transmission, neutralization, or dissipation of frictional charges on the frictional surface of solid-solid triboelectric nanogenerator films (TENGs), which can reduce the output power. The moisture resistance properties of the TENG triboelectric film are needed to overcome these problems. Therefore, this study discusses the role of the TiO2 nanofiller in cassava starch (CS) and polyvinyl alcohol (PVA) nanocomposite matrix that can increase triboelectricity through the formation of hydrogen bonds and the provision of oxygen-free electrons. The research method was to incorporate different concentrations of TiO2 nanoparticles (0%, 0.5%, 1%, 5%, 10% wt, and 15% wt) into the CS-PVA nanocomposite matrix using the solvent casting method. The results showed an increase in surface polarity which was more triboelectric-positive due to the CS-PVA hydroxyl group interacting with water molecules. Increasing the concentration above 5% wt TiO2 increases the density of the CS-PVA nanocomposite film which can significantly reduce water vapor permeability (WVP) and increase water resistance. The TENG performance of the CS-PVA/TiO2 nanocomposite film with a concentration of 15% wt TiO2 under conditions of high humidity (RH, 95%) resulted in an output voltage of 2.5-fold (~70.5 V to ~180 V), and the output current increased 2.6-fold (~5.2 ?A to ~13.7 ?A). ABSTRAK: Persekitaran berkelembapan tinggi dapat mempercepatkan penghantaran, peneutralan, atau pelesapan cas geseran pada permukaan geseran filem nanopengeluaran triboelektrik pepejal (TENG), di mana mengurangkan pengeluaran tenaga. Sifat rintangan lembapan filem triboelektrik TENG diperlukan bagi mengatasi masalah ini. Oleh itu, kajian ini membincangkan peranan pengisi nano TiO2 dalam matriks nanokomposit kanji ubi kayu (CS) dan polivinil alkohol (PVA) yang dapat meningkatkan triboelektrik melalui pembentukan ikatan hidrogen dan bekalan elektron bebas oksigen. Kaedah kajian ini adalah dengan menggabungkan kepekatan nanozarah TiO2 berbeza (0%, 0.5%, 1%, 5%, 10%, dan 15%) ke dalam matriks nanokomposit CS-PVA menggunakan kaedah tuangan pelarut. Dapatan kajian menunjukkan peningkatan kekutuban permukaan yang lebih positif-triboelektrik adalah disebabkan oleh kumpulan hidroksil CS-PVA yang berinteraksi dengan molekul air. Pertambahan jisim kepekatan TiO2 melebihi 5% meningkatkan ketumpatan filem nanokomposit CS-PVA yang boleh mengurangkan kebolehtelapan wap air dan meningkatkan rintangan air dengan ketara. Prestasi TENG filem nanokomposit CS-PVA/TiO2 dengan jisim kepekatan TiO2 15% dalam keadaan berkelembapan tinggi (RH, 95%) menghasilkan voltan keluaran sebanyak 2.5 kali ganda (~70,5 V kepada ~ 180 V), dan arus keluaran meningkat 2.6 kali ganda (~ 5,2 ?A kepada ~ 13,7 ?A).

This study proposes and evaluates an off-grid hybrid electric vehicle (EV) charging system that integrates a 5 kWp solar photovoltaic (PV) array, a 5.5 kW PLN grid connection, and a 12 kWh battery energy storage system controlled by an automatic transfer switch (ATS). The system is designed to maximize solar PV utilization while minimizing dependence on the PLN grid during peak demand periods, thereby reducing carbon emissions, electricity consumption, and charging costs. Experimental testing was conducted using two EV types: a Viar NX electric motorcycle (1.338 kWh battery capacity) and a Wuling Air EV Long Range electric car (26.7 kWh battery capacity). Both vehicles were charged from 30% to 100% state of charge under different operating conditions. Energy generation from the PV system, battery storage performance, and PLN grid contribution were monitored using kWh meters and data loggers. Performance evaluation considered energy production, electricity cost savings, and economic feasibility. Results indicate that the PV system generated an average of 12.38 kWh/day for EV charging. During the dry season, monthly PV generation ranged from 368.40 to 383.78 kWh, while production declined to approximately 286.75 kWh during the rainy season because of reduced solar irradiation. The battery storage and PLN grid effectively compensated for low PV output, ensuring uninterrupted charging. Solar PV supplied approximately 48.06% of the total EV charging energy demand, with charging performance strongly influenced by daytime charging schedules and favorable weather conditions. These findings confirm the technical and economic feasibility of residential-scale hybrid solar PV-based EV charging systems.

The transition to electric vehicles in the transportation sector has had a positive impact on reducing carbon emissions. However, the availability of electricity from renewable energy sources to charge electric vehicles (EVs) remains very limited in both rural and urban areas. The abundant potential of renewable energy sources, such as solar energy, presents challenges in their application as a power source for charging electric vehicles. This study aims to design and analyze the performance of electric vehicle charging using a solar PV tree model. The solar PV installation uses a 152.4 mm diameter iron pipe, with four solar PVs installed in a circle at 90° intervals and a tilt angle of 15°. Eight solar PV trees are installed in a row on the side of the road in the city of Surabaya, geographically located at latitude south 7°9′-7°21′ and longitude east 112°36′-112°54′. The solar PV tree performance measurement method uses IEC 61724-1. The measured electrical parameters consist of voltage, current, power, and solar PV energy efficiency. Electrical energy measurement is divided into two measurements: electrical energy directly used to charge electric vehicles using a kWh meter, and electrical energy stored in energy storage batteries. Solar PV performance testing uses two types of EV loads: an electric car with a charging capacity of 37.9 kWh and an electric bicycle with a charging capacity of 1.75 kWh. Solar PV testing with a tree model can increase sunlight capture with a leaf-like installation model, and it is easy to place in a park or along the roadside. A solar PV system with a capacity of 8 kWp can produce an average of 18.9718 kWh/day, with an efficiency of 2.63% when the sky is clear and sunlight lasts 8 hours. This solar power plant can charge electric bicycles with 1.22 kWh from a full capacity of 1.75 kWh, and electric cars with 14.31 kWh from a full capacity of 37.9 kWh, with an energy loss of approximately 11.5% during charging. Meanwhile, in terms of economic feasibility, with an electricity price of IDR 2,950/kWh, charging electric vehicles (EVs) is economically feasible with a Benefit Cost Ratio (BCR) of 1.23. The solar power plant's investment capital will be returned in eleven years and two months.Keywords: Solar PV trees, EV charging, Electric vehicles, Renewable energy.