The output of wind and solar power generation sources is highly variable. Because they traditionally need to be paired with fossil fuel plants to ensure matching supply with demand across the grid, their apparent cost is significantly lower than their real grid cost – but only if they represent more than a negligible percentage of the total generation on their power grid.

These hidden costs are why it makes sense to add energy storage to solar and wind in a power grid.

Confused? Here is how you can figure it out!