Page 243 - Hybrid-Renewable Energy Systems in Microgrids

220 Hybrid-Renewable Energy Systems in Microgrids

Figure 12.1 Renewable power capacity and annual growth rate, 2000–15.
Source: IRENA, Rethinking Energy 2017: Accelerating the Global Energy Transformation,
International Renewable Energy Agency, Abu Dhabi, (2017).

can be drawn from the grid. The other type of grid connected systems is utility scale.
In this type of grid connected systems, the decentralized stations are managed by the
utilities in a similar way as the large electric power plants. The power generated by
the grid connected system is fed into the central utility grid without serving the local
needs. Some of the important features of grid connected systems are as follows [8].

• A grid connected RES is an independent decentralized power system which is connected to
an electricity transmission and distribution system or grid. This kind of systems is ideal for
applications which are close to the grid.
• The operational capacity of such system is determined by the supply source. The system
would not function unless the supply sources are available.
• Due to the connectivity to the grid, this kind of systems enables setting up relatively large-
scale systems and hence enabling them to operate at high plant load factors resulting in an
improvement in the economic viability of the operation.
• In case of the grid connected RES the grid acts like a battery with an unlimited storage
capacity and can compensate the seasonal load variations. Because of this the overall ef-
ficiency of a grid-connected system is better than a standalone system. In these types of
systems, there is virtually no limit to the storage capacity, the generated electricity can al-
ways be stored. This further improves the system efficiency by reducing the waste of excess
generated power during the off-peak demand times.
• The cost for the interface of the system with the utility grid is incurred in addition to the
initial cost of the system.

1.2 Standalone systems
Standalone systems work independently of the utility grid. These kinds of systems are
more suitable for remote locations where the grid extension is significantly hard and