A new solar energy plant to be built in regional Victoria will run Melbourne's entire tram network by the end of 2018, the State Government has said.

The Government said it would run a tender to build 75 megawatts of new solar farms — most likely in the state's north-west — by the end of next year.

About half of the energy produced by the farms will offset the amount of electricity needed to run 401 trams on Melbourne's network.

Energy Minister Lily D'Ambrosio said the plan was a world first.

"The world is moving to clean energy, we made a commitment as a Government, we continue to uphold that commitment to grow renewable energy," she said.

But Ms D'Ambrosio would not say how much extra the solar energy would cost.

"We won't be disclosing that figure," she said.

"We know that [the] cost of solar plant is coming down every single day and we know that we will drive a very competitive process."

The Government said the project would create 300 new jobs.

It last year approved a $650-million wind farm near Dundonnell, in south-west Victoria, the state's largest.