Renewable Energy technologies are becoming suitable options for fast and reliable universal electricity access for all. Solar photovoltaic, being one of the RE technologies, produces variable output power (due to variations in solar radiation, cell, and ambient temperatures), and the modules used have low conversion efficiency. Therefore, maximum power point trackers are needed to harvest more power from the sun and to improve the efficiency of photovoltaic systems. This paper reviews the methods used for maximum power point tracking in photovoltaic systems. These methods have been classified into conventional, intelligent, optimization, and hybrid techniques. A comparison has also been made of the different methods based on criteria such as tracking speed, efficiency, cost, stability, and complexity of implementation. From the literature, it is clear that hybrid techniques are highly efficient compared to conventional methods but are more complex in design and more expensive than the conventional methods. This review makes available useful information that can be exploited when choosing or designing MPPT controllers.

This paper presents the techno-economic feasibility of using grid-connected PV hybrid systems to supply power in large grid-dependent academic institutions. The study was conducted using the administration building of Moi University in Kenya. The power consumption profile of the building was collected using a PCE-360 power analyzer. The peak load demand was found to be 60 kW. Using random variability constants of 4% for day-to-day and 4% time-step load variability, a peak demand of 70.58 kW was obtained, which was used in our simulation. The solar radiation and temperature data for this site were collected from the weather station of the university. The hybrid system was simulated using HOMER Pro software. It was found from the simulation results that the optimal system was the solar PV/grid without battery storage, which had a levelized cost of energy (LCOE) of KSH 8.78/kWh (USD 0.072), net present cost (NPC) of KSH 27,974,492 (USD 230,813), capital expenditure (CAPEX) of KSH 26,300,000 (USD 216,997), and a simple payback period (SPBP) of 5.08 years for a 25-year life span. This system, when compared to the existing grid, showed an 83.94% reduction in the annual electricity bill of the administration building. These results demonstrate a reduction in energy cost by a renewable energy fraction of 67.1%.

Battery-powered sensor nodes encounter substantial energy constraints, especially in linear wireless sensor network (LWSN) applications like border surveillance and road, bridge, railway, powerline, and pipeline monitoring, where inaccessible locations exacerbate battery replacement challenges. Addressing these issues is crucial for extending a network’s lifetime and reducing operational costs. This paper presents a comprehensive analysis of the factors affecting WSN energy consumption at the node and network levels, alongside effective energy management strategies for prolonging the WSN’s lifetime. By categorizing existing strategies into node energy reduction, network energy balancing, and energy replenishment, this study assesses their effectiveness when implemented in LWSN applications, providing valuable insights to assist engineers during the design of green and energy-efficient LWSN monitoring systems.

The quest for universal energy access continues to be a major concern globally. Renewable energy technologies such as solar PV are viable options to meet this energy poverty with DC-AC power converters playing a major role in solar PV systems. Current designs of these converters suffer from high standby energy consumption and high input threshold voltage. This paper presents the design and implementation of a single-phase DC-AC power converter with low threshold input voltage and optimized standby power consumption. A multivibrator, pulse width modulation signal generator, MOSFETs, and a multiple secondary winding center tap transformer were used in the system design. The results show an optimized power converter having a low input threshold voltage of $10.5V$ and power consumption of$9.49W$.

The increasing demand for sustainable electricity generation necessitates the exploration of innovative technologies. Biomass technology is emerging as a promising alternative to address the energy crisis for low-power devices and reduce reliance on fossil fuels. One of the methods to generate energy from this biomass is by using microbial fuel cells (MFC). However, the efforts made with this technology are still mainly limited at the laboratory scale, limiting its interest and its utilization for electrical power generation. This paper presents the real-life implementation and feasibility of a dual-chamber microbial fuel cell fabricated with concrete. 15 dual-chamber reactors were manufactured, with a volume of 0.5 liters for each chamber. Inside the anodic chamber, a carbon foam measuring 4.5 x 4.5 cm² was placed and used as the anode electrode. Two different electrode materials were used for the cathode electrodes. Six reactors used 4.5 x 4.5 cm² carbon foam while the other 9 used graphite rods of 5 mm diameter and 15 cm long. The anode chamber was inoculated with a mixture of 25% cow dung and 75% tap water and then sealed airtight. Each cathode chamber was filled with 0.5 liters of saline solution. After 7 days of manipulation, the Open Circuit Voltage (OCV) obtained from this investigation ranged from 0.415 V to 0.732 V. That reflects the successful conversion of chemical energy of this waste in the concrete-based microbial fuel cell reactor into electrical energy. The average maximum power density obtained using graphite rod cathodes was 14.15 mW/m² while an average of 20.21 mW/m² was obtained from the MFCs using carbon foam cathodes. When the MFCs were stacked together in series, a total voltage of 8.5 V was observed.