Firmness Is a Function of the Window

Wind and solar do not have a capacity factor problem. They have a window problem — and the window that matters is a week, not an hour

This is part 1 of a series. Next, part 2: The Heat Grid Is the Big One

Wind and Solar Power

The biggest growing source of power over the last 15 years, wind and solar power are both totally dependent on short-term weather. They are not firm in a traditional sense. You can't bank on them being able to generate beyond the forecastable horizon of the weather.