Micro-Grid System for Commercial Building Application

Acciona (experts in infrastructure of renewable energies) was tasked with the installation of a microgrid system using lithium batteries as a renewable energy supply destined to generate, store and supply an important percentage of the electric energy consumption in a commercial building application.

The primary objective of the project was to reduce energy consumption and energy bills for the office building. The system integration involved many tasks including:

  • Installation of equipment: PV modules, battery storage system, backup generator, hybrid inverter.
  • Installation and configuration of the communication system to achieve the complete monitoring and control of the principal equipment.
  • Startup of the new microgrid system integration and communication system connected to the electrical distribution of the office building. 
Specifications :

Voltage : 384 V
Capacity : 106 kWh
Batteries: 60 U27-12XP in a 30s2P configuration Location: Barcelona, Spain
Function : Generate, store, and supply electric energy to an office building
Operating Since : 2016

The equipment chosen and implemented:

PV modules : 76 solar panels were installed on the rooftop of the building for total power of 25.46 kWp.

Battery Energy Storage : The energy storage system is housed in the underground floor in a new technical room designed for lithium ion batteries. 60 Lithium Werks’ U27-12XP LiFePO4 batteries were placed in 2 parallel strings with 30 units in series for a total capacity of 106 kWh.

Inverter : The inverter is also housed in the underground floor which receives and adapts the PV energy to be used by the building users or to charge the batteries. It has a maximum electrical power of 30 kWe.

Auxiliary Diesel Generator : Located in the outdoor parking area is the auxiliary generator which can provide a total electrical power of 50 kWe and only works when the electrical energy generated by PV modules and the electrical energy storage system is lower than the building’s electrical energy demand.

Control and Monitoring System : The installation is controlled by a PLC connected to the systems of the microgrid installation.

The communication protocol also includes MODBus and digital signals to monitor the entire system.

The most important factors for selecting the Lithium Werks’ U-Charge® batteries were discharge rate capability and high cycle life. When testing the U27-12XP, the results met or exceeded the project objectives.

Results of the Test Installation :

  • 15-20% in annual cost savings of energy.
  • Optimization and efficiency of energy management.

Reduction of emissions & greenhouse gases in production of electricity.Low self-consumption buildings using renewable technologies like this demonstration shed a positive light on migrogrid capabilities. It validates the microgrid design for this project is scalable and can be integrated in other types of buildings, especially those with rooftop space. In addition, this project demonstrates the ability to provide electrical energy without the company grid and provides a cost effective solution for generating free electricity.
Information provided by Acciona.

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