2. Introduction
• Hybrid Renewable Energy Systems (HRES) are composed of one renewable and one conventional energy
source or more than one renewable with or without conventional energy sources, that works in standalone or
grid connected mode.
• The applications of hybrid energy systems in remote and isolated areas are more relevant than grid connected
systems.
• In addition, the application of hybrid systems is becoming popular in distributed generation or micro-grids.
3. • The selection of the suitable combination depends on the availability of the renewable resources in the site
where the hybrid system is intended to be installed.
• In addition to availability of renewable sources, other factors may be taken into account for proper hybrid
system design depends on the load requirements such as,
• reliability, greenhouse gas emissions during the expected life cycle of the system, efficiency of energy
conversion, land requirements, economic aspects and social impacts.
8. Advantages of Hybrid Systems
A hybrid energy system can increase the overall efficiency of the system and improve its performance
(power quality and reliability).
Lower emissions: hybrid energy systems can be designed to maximize the use of renewable resources,
resulting in a system with lower emissions.
Acceptable cost: hybrid energy systems can be designed to achieve desired attributes at the lowest
acceptable cost, which is the key to market acceptance.
They provide flexibility in terms of the effective utilization of the renewable sources.
9. Barriers:
Maximum power extraction: When different V-I characteristics voltages are connected together extracting maximum power is difficult for a
constant load.
Stochastic Nature of sources: These distributed sources are site specific and diluted. So, the design of power converters and controllers has
to be designed to meet the requirement.
Complexities in matching voltage and frequency level of both inverted DC sources and controlled AC sources.
V-I characteristics depends on atmospheric condition, which is varying time to time. Forecasting of these sources is not accurate.
Storage: Most of hybrid systems require storage devices which batteries are mostly used. These batteries require continues monitoring and
increase the cost, as the batteries life is limited to a few years.
Coordination: Frequency mismatch arises between both systems. Hence it leads instability of the overall system.
Power Quality: Variety of power electronics converters are involved in the power conditioning of hybrid energy system between sources to
load. These power converters generate many harmonic components to the load which cause various disturbances to the load/power
distribution system.
