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UNSW practices what it preaches

May 2005 saw the installation and commissioning of a 42-kilowatt (peak power) grid-connected photovoltaic system on the north-facing roof of the Quadrangle building.

Photovoltaic cells convert sunlight to electricity, and we've used the laser-grooved, buried contact solar cells, sometimes known as "Saturn Cells", for this project. These are the highly efficient and world-renowned type of cell, developed by UNSW research teams.

The cells are installed in modules that closely follow the contour of the roof*. The output of the system is fed into the normal power supply of the Quadrangle building, reducing the demand on our electrical mains. It will also provide enough energy to run the equivalent of 300 computers on campus every day, and save more than 80,000 kg of greenhouse gas emissions each year.

* The modules have been placed at a distance from either side of the clock tower to minimise shading, which would otherwise reduce the output of the system significantly. The ideal pitch angle is more like 25 degrees for Sydney's latitude, but in this case a slight loss in performance was accepted for the sake of aesthetics.

This is the first step with our ambitious objective to provide 10% of Campus electrical demand with renewable energy by 2015. The next step in the plan is for a 50kW system on the roof of the Heffron building, which is currently being refurbished.

To put that in perspective, world solar photovoltaic (PV) market installation in 2004 amounted to 927 Megawatts, representing a growth of 62% over 2003 installations.

What are the benefits for UNSW ?

• Reduced greenhouse gas emissions of approximately 80,000 kg CO 2e per year.
• Additional educational resources - testing and monitoring.
• Showcasing UNSW technology (the output will be monitored and publicly displayed)
• Potential Greenhouse Gas trading credits at market value
• Fixed energy cost for 25years
• Helps promote the University as a responsible corporate citizen
• Helps defer the need for an upgraded electricity supply to Kensington campus

Technical Information

The two arrays comprise 252 - BP5170S modules. The system is configured so that each 9 modules are connected in series, called a 'string' . Each two strings are fed into one of 14 - BP Solar Gci2500 Inverters. The inverters change the direct current produced by the cells into an alternating current at a voltage suitable to the requirement - in this case 240v.

SMA Sunny Boy Controllers are connected to each inverter, which are housed in a Plantroom behind the clock tower. These controllers constantly log the system data for analysis and display. In this installation, wind speed, ambient temperature, module temperature and solar irradiance are also logged.

The system was installed by Solar Technology Australia Pty.Ltd.

More preaching ...

The photovoltaic modules are clearly seen from the Quadrangle lawn. To take advantage of this, a touch-screen display adjacent to the Quadrangle building has been developed to promote renewable energy on campus, and specifically to describe the system.

The NSW Department of Energy, Utilities and Sustainability saw the value of such a display and awarded UNSW with a $44,000 grant to help fund this component.

The information will be displayed in various forms and include:

• An audio description of the system
  
  
• PV system layout and component details
  
  
• Instantaneous outputs - power, solar radiation, wind speed, temperature
  
  
• Energy delivered for each day since installation
  
  
• Comparison of performance for different seasons and weather
  
  
• Total energy delivered and CO 2-equivalent saved
  
  
• Typical system efficiencies of each section
  
  
• Entry level Greenhouse information and energy efficiency hints
  
  

Stage two of the project allows the system to be interrogated via www.energy.unsw.edu.au with accessibility options for disabled users.

Stage three will be for the display to show inputs from other sources including for example, other PV systems on campus or general campus energy metering data.

UNSW Energy Management funded the system from savings made through energy conservation projects over previous years. Some of these initiatives are also described on the same website