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Indonesia's electricity needs are increasing in line with increasing population and living standards. Renewable energy is an alternative in avoiding dependence on conventional PLN electricity. This research is a further study of solar energy as an alternative energy to meet the electricity needs of Institut Teknologi Sumatera (ITERA) which always increases every year with the increasing number of students and the infrastructure of lecture infrastructure. Research on the potential of solar energy at the ITERA has been carried out before using conventional methods. This study further examines the potential of solar energy by considering various factors. This study uses solar cells with 100 WP specifications and uses Arduino UNO instrumentation to facilitate the measurement of current and voltage automatically which can be stored directly in memory cards. Based on the measurement results obtained a maximum power value of 66 watts that occurs at 11:00 and 12:00 WIB.   Keywords: Solar cell, solar energy

In this study, the microstructural, optical, and magnetic properties and specific absorption rate (SAR) of bismuth ferrite/SiO2 nanoparticles were successfully investigated. The coprecipitation method was used to synthesize the nanoparticles. X-ray diffraction patterns showed the presence of sillenite-type Bi25FeO40 with a body-centered cubic structure. The crystallite size of Bi25FeO40 was 35.0 nm, which increased to 41.5 nm after SiO2 encapsulation. Transmission electron microscopy images confirmed that all samples were polycrystalline. The presence of Si–O–Si (siloxane) stretching at 1089 cm−1 in Fourier transform infrared spectra confirmed the encapsulation of SiO2. Magnetic measurements at room temperature indicated weak ferromagnetic properties of the samples. The coercivity of the bismuth ferrite nanoparticles was 78 Oe, which increased after SiO2 encapsulation. In contrast, their maximum magnetization, 0.54 emu g−1, reduced after SiO2 encapsulation. The determined bandgap energy of the bismuth ferrite nanoparticles was approximately 2.1 eV, which increased to 2.7 eV after SiO2 encapsulation. The effect of SiO2 encapsulation on the SAR of the samples was investigated using a calorimetric method. The SAR values of the bismuth ferrite nanoparticles were 49, 61, and 84 mW g−1 under alternating magnetic field (AMF) strengths of 150, 200, and 250 Oe, respectively, which decreased after SiO2 encapsulation. The maximum magnetization and the AMF strength influenced the SAR of the nanoparticles. The results showed that SiO2 has a significant effect in determining the microstructural, optical, and magnetic properties and SAR of the nanoparticles.

Intisari — Saat ini masyarakat Indonesia cenderung sering melakukan pemborosan pada penggunaan listrik. Di sisi lain energi listrik di Indonesia mayoritas dihasilkan dari pembangkit listrik tenaga uap, yang membutuhkan bahan bakar dari sumber daya alam yang tidak dapat diperbaharui. Sehingga tingginya permintaan dan kejadian pemborosan dalam penggunaan listrik dapat meningkatkan konsumsi sumber daya alam serta polusi udara. Maka dari itu, dalam penelitian ini diusulkan sebuah solusi melalui sistem peringatan dini yang dapat menumbuhkan kesadaran masyarakat untuk melakukan penghematan dalam penggunaan listrik. Sistem ini membutuhkan data masukan berupa jumlah pemakaian listrik dalam 6 bulan terakhir, yang selanjutnya akan dibentuk pola penggunaan listrik dari setiap pengguna menggunakan analisis regresi linier. Selanjutnya dari pola yang diperoleh, diambil informasi pemakaian listrik perhari untuk dijadikan ambang batas pada pemberian peringatan pemborosan yang diprediksi akan terjadi. Sedangkan untuk penyebaran informasi ke pengguna tentang prediksi pemborosan, sistem ini menggunakan fasilitas SMS Gateway. Hasil penelitian ini adalah sistem yang dapat memberikan peringatan kepada pengguna jika penggunaan listriknya sudah melebihi ambang batas tertentu.Kata kunci — Sistem peringatan dini, pemborosan penggunaan listrik, analisis regresi linier, sms gateway. Abstract — Nowadays almost Indonesian people get inefficient management on the electricity usage. While,  Indonesia is still use steam power plant to produce the electricity power, which require fuel from non-renewable natural resouces. So the highness of demand and the occurrence of inefficiency from the electricity usage may increase the consumption of natural resource and the air pollution. Therefore, a solution through an early warning system are proposed in this study, that would increase awareness of the people to use the electricity power become more efficient. This system require the data of electricity usage from each customers in the last 6 months, that will be generated the electricity usage trend from each customers using linear regression analysis. Furthermore from the trend data obtained, the daily electricity usage information will be taken to use as a threshold for giving the inefficiency warnings from electricity usage that will occur from the available prediction. Moreover, in this study also use SMS Gateway for send the information of inefficiency electricity usage prediction automatically to each customers. Finally, the experimental result from this study is the system that can provide a warning to customers if their electricity usage run over the certain thresholds.Keywords— Early warning system, inefficient of electricity usage, linear regression analysis, sms gateway.

Abstrak -Panel surya dapat diketahui kinerjanya dengan cara mengukur parameter arus dan tegangan namun untuk mendapatkan informasi yang akurat dan berkelanjutan maka perlu adanya sistem pemantuan terhadap panel surya tersebut. Sistem pemantauan pada penelitian ini dibuat dengan berbasis ATMEGA328P, ESP 8266, sensor arus dan tegangan. Dapat disimpulkan bahwa untuk sistem pemantuan kinerja panel surya dalam pengujian memiliki galat sebesar 0.2% untuk sensor tegangan, 0.17 % untuk sensor arus. Untuk data dari sistem pemantuan menunjukkan nilai rata-rata tegangan dan arus sebesar 20.75 volt dan 2.81 ampere dengan standar deviasi 0.32 volt dan 0.14 ampere serta 15 detik untuk jeda pengiriman data ke platform penyimpan data. Kata kunci -Panel Surya, Arus, Tegangan, Pemantauan.Abstract -Solar panels can be accessed by measuring the current and voltage parameters to obtain accurate and necessary information, so a system of monitoring for the solar panels is needed. The improvement system in this study was made based on ATMEGA328P, ESP 8266, current and voltage sensors. It can be concluded that the solar panel monitoring system in the test has an error of 0.2% for voltage sensor, 0.17 % for current sensor. Data from the monitoring system, the average voltage and current values are 20.75 volts and 2.81 amperes with a standard deviation of 0.32 volts and 0.14 ampere then it takes 15 seconds for time delay in sending data to a data storage platform.