Off-grid systems enable the supply of electrical energy to buildings where connection to the
public power grid is not possible or economically justified. Due to the variable generation
from renewable energy sources, proper sizing of individual components is important in such
systems. This thesis examines a hybrid off-grid system for supplying a single-family house,
consisting of a photovoltaic system, a battery energy storage system, and an electric
generator.
The aim of the thesis was to determine a technically feasible and economically optimal
system configuration. The analysis was based on actual electricity consumption data of the
building and solar irradiation data. A simulation model was adapted in MATLAB for a fullyear simulation of the system operation in 30-minute intervals. An optimization procedure
was used to evaluate different combinations of the number of photovoltaic modules, battery
storage capacity, and generator power. Based on the results and a review of commercially
available equipment, specific system components were selected.
The final system consists of a 23.92 kWp photovoltaic system, a battery energy storage
system with a capacity of 61.44 kWh, a 16 kW hybrid inverter, and a 6 kW diesel generator.
The simulation showed that the system fully covers the annual electricity consumption of the
building, which amounts to approximately 11.5 MWh. The photovoltaic system produces
approximately 28.7 MWh of electrical energy per year, while the generator supplies an
additional 2.9 MWh and operates for 603 hours. The estimated annual cost of the system is
approximately €3,610, which is about 91% higher than the cost of electricity supplied from
the public power grid. The results show that a fully off-grid supply is technically feasible, but
economically less favourable when a grid connection is already available.
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