The NSW opposition leader Luke Foley has been left red-faced after being caught out promising a policy that the Berejiklian government has already begun.

As reported by Fairfax Media, Mr Foley promised in his budget reply speech on Thursday to "massively increase" solar generation in the state if elected in 2019 by installing panels on the rooftops of government buildings including schools, hospitals and police stations.

Solar panels can save the government big money. Credit:Rob Homer

However, the government already has the nub of that policy already under way, having issued a tender on June 9 for businesses to offer to deliver rooftop solar photovoltaics.

A "wide variety of government buildings" will be eligible for these panels, including schools, TAFEs, offices, art facilities, hospitals, and even correctional centres, the tender shows.