Monika Bieri

Optimal PV and storage sizing for PV-battery-diesel hybrid systems

This paper studies the sizing problem of PV-battery-diesel hybrid systems using convex optimization approach. The case study takes place in an Indonesian island where the load demand fully depends on a single diesel generator (DG). The goal is to optimize the number of solar panels and batteries to be installed to reduce the total cost of the system over the lifetime of 25 years. Real solar irradiance and temperature profiles, together with forecasted diesel prices, are used. A heuristic method, particle swarm optimization, is also employed as a benchmark for performance evaluation. Our results show that the total cost obtained from our proposed method is the lowest since it reaches the global optimal solution. The advantage of a PV-battery-diesel hybrid system over systems operated by a single DG and systems formed by a single DG and solar panels is exposed as, in comparison to them, it achieves a reduction of the total cost (between 7% to 11% and 0% to 4%, respectively) and of the CO2 emissions (between 19% to 29% and 10% to 21%, respectively).

Levelized Cost of Solar Thermal System for Process Heating Applications in the Tropics

In ASEAN region, buildings and industry sectors account for about 24% and 28% of total energy (415 Mtoe) consumption, respectively. A significant share of the building and the industrial energy consumption is for process heating applications, i.e., hot water for manufacturing and services, in the temperature range of 60–150 °C. Thus, an effective utilization of solar thermal energy for process heating applications could contribute to a reduction of fossil energy consumption in the regions where solar energy is available all year-round. For industrial heating applications, thermal efficiency of solar collectors is typically ranging between 60% and 75% depending on collector type and fluid temperature inside the collector. The levelized cost of thermal energy (LCOEth) for industrial heating from solar thermal systems is determined being in the range of 5–9 USD cents per KWhth with strong sensitivity toward collector price, collector efficiency, and financial parameters such as financial leverage, discount rate, and taxes in each country.