The Collie branch will be finishing solar installation in the coming week, according to Lisa Holley, the bank's corporate and social responsibility executive manager.
Bankwest is owned by the Commonwealth Bank of Australia and Holley said another 16 CBA branches around the country also had solar installations.
The other two branches in WA which run mostly on solar power are the Geraldton and Margaret River outlets.
Solar panels on the roof of Bankwest's Geraldton branch.
She said the switchover in both locations had been very successful. "We are not 100% off grid – we still draw from the grid and on cloudy days and overnight (as there’s power needed to run systems at the stores 24/7).
"On average we use around 50% solar and 50% from the grid. However, on some sunny days and at the weekends the two branches are 100% solar."
Holley said since installation in Geraldton, "we saved about 45MWh of energy and have reduced our carbon footprint at a rate of 37 tonnes of CO2 per year. That’s almost the same amount of CO2 produced by a bus driving to the moon".
"In Margaret River we are saving $7000 in electricity costs, 27MWh in energy and 23 tonnes CO2 annually. We’re actually creating so much energy we’re able to put some back into the national grid.”
Holley said the bank hoped to get solar installed in about 25 to 30 sites before the end of the financial year.
System size: 15.86 kW
System cost: $30,103
Payback period: 2.22 years
Installation date: 11/07/2016 (took two days)
System size: 20.80 kW
System cost: $37,354
Payback period: 3.35 years
Installation date: 8/07/2016 (took two days)