AGL will spend $80 million on maintenance at Bayswater and Liddell coal-fired power stations to ensure they are able to meet peak demand during summer.
The work is part of a $150 million investment the company is making across its key energy assets to improve summer readiness.
"This program aims to provide additional security to our diverse and flexible portfolio of coal, gas and renewables and helps us to meet the needs of our customers and the National Electricity Market," AGL executive general manager of group operations Doug Jackson said.
"We are working closely with our industry peers and the Australian Energy Market Operator to plan for the needs of customers and prepare for unpredictable extreme weather events."
AGL is investing heavily in renewable energy projects to offset the shutdown of the 2000 megawatt Liddell power station in 2023 and adjoining Bayswater in 2035.
The projects include the proposed $400 million Newcastle gas-fired power station near Tomago, which is designed to increase firming capacity in the electricity market.
Despite that, Tomago Aluminium chief executive Matt Howell said last week that renewables still fell short of being about to provide the firmed capacity required by energy-intensive industries such as aluminium smelters.
Mr Howell's comments followed a warning by one of the company's owners that the future of intensive manufacturing industries were in jeopardy due to the high cost of energy.
Mr Jackson said AGL was determined to meet the needs of all its customers.
"We provide an essential service and we know that no matter what month of the year it is, customers expect their homes and businesses to continue operating effectively," he said.
"Our job is to ensure we do everything we can to deliver on this expectation, which is why for the last nine years we have run a summer readiness program, where we take the lessons from previous summers to build a proactive program of work."
AGL announced in August that it had signed an agreement with Idemitsu Australia Resources to undertake an engineering feasibility study for a proposed 250-megawatt pumped hydro project at Bells Mountain, near Muswellbrook.
The agreement follows on from an initial concept study which explored the viability of utlising the void on the Muswellbrook Coal site.
The company also recently completed the Barker Inlet Power Station in South Australia.
The $295 million plant provides 210 megawatts of dispatchable power via the largest gas engine on the market and is capable of reaching full-capacity in five minutes.