There are plenty of companies out there who want to install the largest solar photovoltaic (PV) array on your rooftop. But should you let them?

One of our clients was recently faced with just this dilemma for their new facility in western Sydney.

Although they were a large energy user, their demand profile was very flat so their energy costs were low. But they were wary about future energy cost variability. As well, the international parent had offered to support sustainability projects, and so they needed to have a very accurate picture on what the before and after costs would be.

To help them, we

• modelled the hourly energy output from a solar array for the new facility location
• used an energy consumption profile for another site, based on 15-minute metered interval data
• compiled a model of the system to estimate the costs with and without solar PV

The flexibility of the model allowed us to run a number of different scenarios to establish the optimum PV array size. Once we had established this value, we were able to provide an accurate number to the Board on the costs and benefits of the project. The model was used to:

• determine the optimum size of the PV system
• determine the economics of a PV system that filled the roof
• what size PV system would 100% offset annual energy consumption
• what adding batteries to the system, with and without PV, would cost and save

We presented this work to the Board, along with an energy market risk assessment.