The solar panels have been installed at council's administration building, the Hunter Valley Visitor Information Centre and Cessnock Library.

General manager Lotta Jackson said it's fantastic progress and use of council's savings under the Revolving Energy Fund, which was established in 2015.

"The purpose of this fund was to establish an internal loan system for investing in energy efficiency," Ms Jackson said.

"All savings made from investments are returned to the fund and can be re-invested into the next energy-saving projects.

"It's a great cost saving for council with it estimated to save $12,000 per year on council's electricity bill for the administration building and all systems will be paid off from savings in 5.5 years."

Also under the Revolving Energy Fund, council has replaced fluorescent lights with LEDs across many of its sites, including the works depot, the visitor information centre, Cessnock Aerodrome, Cessnock Performing Arts Centre and the library.

This has reduced the administration building's monthly electricity bill by about $1000, with all savings put straight back into the fund.

Council plans to install more solar panels on Cessnock Performing Arts Centre and Kurri Kurri Library using the next savings from the Revolving Energy Fund.