Page 324 - Advances in Renewable Energies and Power Technologies

2. Classification of Photovoltaic Irrigation Systems 297

some specific cases, these systems had solar trackers, but electrochemical storage
batteries were not needed, as energy was stored by lifting water to an elevated
tank. These early PV irrigation systems were low-power installations (<6 kW)
whose size was limited by the high cost of PV modules and the need for specific
DC pumping groups. The commercial development of these solutions was scarce,
which meant that the variety of products was limited. On the contrary, the grid-
based irrigation systems that used asynchronous motors did have much more com-
mercial success.
Great efforts have been made over the last 50 years to develop more efficient
solar-based water pumping systems. Among the first PV irrigation installations,
the very first was that of Campana, built in the 1970s in Corsica. This facility served
as the basis for installing 25 PV pumps under the “Mali Aqua Viva” project. Since
then, there has been a stable market for small power (<10 kW) PV pumping systems
dedicated to irrigation and water supply for rural settlements.
Several factors have made it possible for the existing PV irrigation systems to be
profitable in Mediterranean climate conditions. One of them is the gradual decline in
the price of the PV Watt Peak (Wp), which reached the value of 0.5 V/Wp in 2015.
Another is the fast-paced evolution of electronic solutions that allow the conversion
of DC into alternative current (AC) (inverters and frequency inverters) at increas-
ingly competitive prices.
PV pumping systems are currently gaining interest due to their numerous
advantages:

• They do not depend on the existence of an electricity distribution network.
• They do not rely on portable electric generators that consume fuels, which either
pollute the environment or are expensive and difficult to obtain.
• Their design is simple, as it does not require a battery bank.
• They have a long life, are highly reliable, and require minimal maintenance.
Many scientific research works have been performed in the last two decades with
the aim of improving PV irrigation systems. Table 9.1, adapted from Chandel et al.
[23], summarizes some of these recent studies.

2. CLASSIFICATION OF PHOTOVOLTAIC IRRIGATION
SYSTEMS
PV irrigation systems are composed of two primary and highly interrelated subsys-
tems, namely the PV subsystem, which is responsible for supplying the energy
required, and the irrigation subsystem, which demands energy. For the PV irrigation
systems to perform properly, the relationship between these two subsystems has to
be established by applying rational and scientifically based methods. A primary clas-
sification can be made according to the characteristics of both PV and irrigation
subsystems.