Solar Diesel Hybrid

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Solar-Diesel Hybrid Power Systems

Solar-Diesel Hybrid Power SystemsDiesel – Solar Hybrid system based on photovoltaic is considered an effective option to electrify remote and isolated areas (e.g. construction site) far from grid. This is true for areas that receive high averages of solar radiation annually. Using diesel generator as a standby source will make utilization of hybrid systems more attractive.

It is found that electrifying rural small community using this Diesel–Solar hybrid system is very beneficial and competitive with other types of conventional sources as it decreases both operating costs and pollutant emissions.

Different types of renewable energy sources are nowadays used to supply different applications in rural and urban areas & construction sites. Increased reliability and energy security issues are of the most benefits that can be achieved by using Diesel-Solar hybrid renewable systems. Diesel-Solar Hybrid systems that depend on photovoltaic (PV) are considered the most popular among other types of renewable systems. The main advantages of this technology are their low maintenance costs and low pollutant emissions.

The block diagram of this system is shown in Figure below. The type of the Diesel-Solar hybrid system and its configuration depend mainly on the availability of the renewable source in the location selected for installing this Diesel-Solar hybrid system. For the areas, with average daily solar radiation intensity on a horizontal surface 5.6 kWh/m2, these values are relatively considered high and very encouraging for using PV generators.

How the Solar-Diesel system operates:

  • The solar photovoltaic panels charge the batteries to store electric power during the sunlight hours.
  • The inverter system charges the batteries when the diesel generator is running.
  • The diesel generator automatically starts charging the batteries if the batteries state of charge is below a certain level.
  • After the state of charge of the battery bank reaches the appropriate level the diesel generator automatically stops.
  • The system compares the priority of different loads in order, when the state of charge of the batteries bank is low, the Solar-Diesel Hybrid system will cut off the less important electrical loads to extend the electric power supply to the important loads.

Optimization OF Diesel – Solar Hybrid Power System

Optimization of sizes of different components constructing the hybrid system is one of the important issues that shall be considered while designing this system. Maximizing utilization of the renewable source, minimizing the cost of generating energy and minimizing the pollutant emissions are objective functions of this optimization. It is concluded that a PV/diesel generator hybrid system is the more feasible system compared to a diesel generator system or standalone PV system for most of cases.

An economic feasibility study is recommended to be conducted for design of a Diesel-Solar hybrid system consisting of photovoltaic (PV) panels, a diesel generator as a backup power source and a battery system. A simulation program using iterative approach is developed to optimize the sizes of PV system and battery bank. Specifications of the hybrid system components are then determined according to the optimized values. Solar radiation data is firstly analyzed and the tilted angle of the PV panels is also optimized. Costs of different components, hourly solar radiation and ambient temperatures and other design considerations are inputs of the simulation program.

Software are available to optimize a suggested PV/diesel hybrid system. It is concluded that the most optimal configuration in for the scenario that involves PV and diesel. A similar study done for a village in Saudi Arabia, and suggested many configurations of the desired system using different types and sizes of components to select the optimal one. In software, different components making the hybrid system can be modeled, studied, specified, and chosen appropriately to minimize the system cost.

Operation of Diesel – Solar Hybrid Power System

Several modes are available for operation of Diesel-Solar Hybrid System which can be programmed. Below is commonly used mode.

The energy generated by the PV panels and stored in the battery bank (of Diesel-Solar Hybrid System) has priority to supply the load. When the battery is discharged to its minimum allowable level, the diesel generator as a backup source is switched on. For each hour step, the developed simulation program compares the load requirement and the available generated energy by the Solar PV system. A decision to charge the battery, discharge it or operate the diesel generator will be taken according to this comparison. In certain cases where the generated energy exceeds the load requirement and the battery bank is fully charged, this excess energy is consumed by a dump load.

A decision to operate the diesel generator is taken when the battery is discharged to its depth of discharge level and there is no sufficient generated energy by Solar PV system to supply the load. This case continues until the battery is fully recharged where the bidirectional inverter works as a rectifier and permits to charge the battery.


Operation of Diesel – Solar Hybrid Power System


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