What does that even mean? Electricity is fungible. Suppose that ten megawatts of coal power and one megawatt of solar power goes into a power grid, and I draw 100 kilowatts out of that grid. I ask the power company to declare that my office is "powered by renewable energy". They can happily write me a piece of paper, saying that my 100 kilowatts of consumption "comes from" the one megawatt of solar input. But it doesn't change the amount of coal that gets burned, it's just moving numbers around.
Did you read the article? They're specifically investing in building solar farms and other renewable energy sources, as solar becomes more cost efficient it will push back on new developments of coal plants and other dirty energy sources.
This is not about the short term results, this is putting a strategical bet on clean power. And as you can see from Apple's other business, they're all about long term gains.
Total, the huge oil and gas company, also invests in renewable energy. They have a whole list of investments, one can read through them all on Crunchbase: