Enbridge, Canada's No. 2 pipeline company, said the investment would make the Sarnia site North America's largest solar plant, producing enough electricity to power 12,800 homes and saving 39,000 tonnes of carbon-dioxide emissions a year.
In October, Enbridge bought the Sarnia project in southern Ontario from developer First Solar Inc, one of the world's largest producers of the photovoltaic cells that convert sunlight into electricity.
The first 20 megawatt phase of the project has just entered commercial service.
Enbridge is best known as the operator of North America's largest crude oil pipeline network and ships the lion's share of Canada's oil exports to the United States on its lines.
But the company has been making a push into the renewable energy business, operating four wind-power projects, with a fifth, 99-megawatt project slated to be completed next December.
The solar expansion is also expected to be complete by December 2010.
"With this investment, we will have interests in more than 470 megawatts of green power capacity from our five wind energy projects, expanded solar facilities, four waste heat recovery facilities and the world's first commercial application of hybrid-fuel cell technology," Pat Daniel, Enbridge's chief executive, said in a statement.
First Solar will build and maintain the Sarnia project and Enbridge has a 20-year agreement to sell the power to the Ontario Power Authority.