Energy Management for Photovoltaic Irrigation with a Battery Bank

1. Introduction

Crops irrigation is a serious issue in many developing countries, as the lack of a reliable electricity grid in remote areas makes irrigation inefficient or simply impossible, affecting seriously the productivity and reducing the crops quality (Shankara, 2005; Canadian ministry report, 2008). A typical solution is the use of diesel generators (Gensets); however the running cost of these Gensets is inadequate, due to the increase in fuel cost (Sahin, 2013), and the need of a constant reliable fuel supply (Al-Islam Khan, 2013; AlSmairan, 2012; Bouzidi, 2011). To solve this problem, photovoltaic systems are being currently deployed in remote areas (Bouzidi, 2006; Colantoni, 2013; Shama, 2012; Yahyaoui, 2014): this problem is frequently studied in the literature, as specific energy management systems must be designed to satisfy the crops irrigation patterns: see for example (Yahyaoui, 2013; Yahyaoui, 2014).

This paper concentrates on photovoltaic installations coupled with a battery bank (Figure 1), as they ensure energy availability even if the irradiation is low, so stored electricity can be used for secondary uses, for irrigation at night or for irrigation in cloudy days. Based on some previous proposals by the authors (Sallem, 2009; Yahyaoui, 2014), a general fuzzy algorithm is proposed here, that based on models of the water volume needed by the plants and meteorological measurements, acts on the relays which links the installation components, to ensure the load supply and the batteries safety.

Figure 1.

Photovoltaic pumping and irrigation system under study

The decision on the connection or disconnection of the components will be done by a fuzzy management algorithm, depending on the estimated Photovoltaic Panel Generation , the power required by the pump , the water level in the tank , and the battery depth of discharge dod models.

The fuzzy management algorithm is detailed in section 2, where the management strategy and the algorithm’s execution are explained in depth. Some results are presented and discussed in section 3. Finally, section 4 gives a conclusion.

2. Energy Management Proposal

2.1. Energy Management Specifications

The objectives are schematized in Figure 2, and are as follows:

Figure 2.

The proposed energy management

• 1.

  Provide the required irrigation when needed, by storing water in the reservoir.

• 2.

  Protect the batteries by disconnecting them from PVs and the pump when they are not used.

• 3.

  Keep the depth of discharge of the batteries (dod) always between two pre-fixed values, to increase their lifetime by avoiding deep discharge and excessive charge.

• 4.

  When the reservoir is enough full, store the excess of energy in the batteries.