Analysis of PV-Diesel Hybrid System: A Comprehensive Overview

This report provides a detailed analysis of PV-diesel hybrid systems, which integrate photovoltaic systems and diesel generators to supply electricity, aiming to reduce diesel generator operation. The report explains the system's working principle, including the roles of solar photovoltaic systems, diesel generators, and batteries for energy storage. It further analyzes energy production, highlighting the contribution of solar power and the need for diesel backups, especially during periods of low solar irradiation. The economic costs associated with the installation and maintenance of the hybrid system are compared with those of traditional diesel/battery combinations. The report also assesses the environmental impact, emphasizing the reduction of greenhouse gas emissions due to decreased diesel consumption. The analysis is supported by references to relevant research and the use of HOMER software for system design optimization.

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I. ANALYSIS OF THE PV-DISEL HYBRID SYSTEM
The PV/diesel hybrid system incorporates both photovoltaic system and diesel generator in
supplying electricity to the load. This technology aims in reducing the operation hours of a diesel
generator in every possible means.
1.1 How PV/diesel hybrid system works?
The figure below shows a schematic design of a PV/diesel hybrid system
Figure 1: PV/diesel hybrid system configuration Source:
https://www.sciencedirect.com/science/article/pii/S0142061512000373
The solar photovoltaic system and the diesel generator are integrated to harness a clean solar
power and at the consequently compensate for the reduction in the sun incident rays [1]. The
battery is used for storage purposes to ensure there is uninterrupted steady supply of electricity to
the load terminal. Moreover, the use of diesel generator is not encouraged since it is costly and
produce a lot of noise with emission of harmful gases to the environment causing air pollution.
The use of two sources of energy in collaboration with the battery provides a smooth and
distributed output [4]. This makes the hybrid system to be more reliable and efficient.

The hybrid system operates as follows; under normal operations, the photovoltaic system will
supply the load terminal with enough electricity with excess being stored in the battery until it is
full. In case, there is excess energy after maximum storage is reached, the excess will be fed into
a dump load. In a situation whereby the PV array and the battery is not capable of supplying
enough electricity to the load, the diesel generator will automatically switch on to provide the
power needed in the load or charge the battery [2].
The inverter is used in the system to help convert the electric current into either an Alternating
current (AC) or Direct Current (DC) depending on the direction of flow of electric power [2].
The PV output uses the DC while the diesel generator output uses the AC. The battery makes use
of the DC to charge while the load can sometimes require the AC diodes to run motors, power
equipment’s, and fridges. Hence the need for an inverter for optimum power conversion and
control in the system. Proper management of the hybrid system will ensure maximum fuel
economy and minimizes emission of CO2.
II. ANALYSIS OF HYBRID POWER SYSTEM (HPS)
The design of the hybrid PV/diesel energy system was obtained using the HOMER software. The
results obtained meant to provide an optimal combination of PV and diesel generation with
energy storage mechanism to provide maximum gains. The main objective of this hybrid system
is to provide a renewable source of energy with a reliable supply of energy needs at a lower cost.
2.1 Energy production
The hybrid system is not solely replaced by solar power, however, there is need for backup of the
diesel generator. This combination could only offset the quantity of diesel used [2]. This
configuration is mainly done In favor of the photovoltaic system due to its sustainability aspects
and climatic changes in order to accommodate the load demands [3]. Most of the electricity
throughout the months is generated by the photovoltaic system apart from the rainy seasons.
2.2 Energy Flows
Hybrid PV/Diesel System with a storage; the PV hybrid system is made up of a PV charge
controller losses, DC to AC conversion losses both directed to energy flow into the load and for

energy flowing to the battery and the energy loss during storage trip [5]. On the part of a
generator, the AC to DC conversion losses affect the energy current that is not directly
transported to the load [1].
2.3 Economic Costs
The cost of capital in installing the PV/diesel hybrid system with a battery storage is three times
more than the cost of capital of installing a generator and battery combination [2]. However, the
payback over the life cycle of the development in terms of the net cost is less than one half of the
operation and maintenance cost of the generator and battery combination [5]. This means, there
is more benefit accrued in the PV/diesel hybrid system over the life time of the system. The Net
Present Cost (NPC) incurred in the installing the PV/diesel hybrid system is lower compared to
the NPC of installing the diesel/battery combination due to less fuel consumption, with fewer
battery for storage needed and the replacement of battery is factor of maintenance of this system
[6].
2.4 Environmental Pollution
On environmental perspective, when the operational hours of a diesel generator is reduced, it
means that the fuel consumption will also be reduced which further translates to a reduction in
the emission of greenhouse gases whereas in a situation where the diesel generator is highly
depended on as a source of electric power, it means more fuel will be consumed in the process
which will eventually lead to an, increase of greenhouse gases emission [6].

III. REFERENCES
[1] M. Jovanović, “An analytical method for the measurement of energy systems sustainability
in urban areas,” FME Transactions, vol. 36, no. 4, 2008, pp. 157–166.
[2] R. Dufo-López and J. L. Bernal-Agustín, “Design and control strategies of PV-diesel systems
using genetic algorithms,” Solar Energy, vol. 79, no. 1, 2005, pp. 33–46.
[3] A. Mellit, “Sizing of photovoltaic systems: a review,” Revue des Energies Renouvelables,
vol. 10, no. 4, 2007, pp. 463–472.
[4] A. Gupta, R. P. Saini, and M. P. Sharma, “Steady-state modelling of hybrid energy system
for off grid electrification of cluster of villages,” Renewable Energy, vol. 35, no. 2, 2010, pp.
520–535.
[5] S. Ashok, “Optimised model for community-based hybrid energy system,” Renewable
Energy, vol. 32, no. 7, 2007, pp. 1155–1164.
[6] D. K. Lal, B. B. Dash, and A. K. Akella, “Optimization of PV/Wind/Micro-Hydro/diesel
hybrid power system in homer for the study area,” International Journal on Electrical
Engineering and Informatics, vol. 3, no. 3, 2011, pp. 307–325.