We don’t use energy – and in particular, electricity – at a constant rate. Over the course of a day, we use more power during peak hours. And over the course of a year, we use more electricity in the winter, when days are shorter and the weather is colder, and in the summer, when people run air conditioners to stave off the heat.
Utilities and grid operators call what’s coming out of the grid, based on what we know about how people use electricity, the forecasted load. The amount of electricity coming into the grid from solar panels and wind turbines is the variable production (variable because the wind doesn’t always blow and the sun doesn’t always shine).
The difference between the two at any given time is called the net load. It’s essentially the amount of electricity the grid has to supply from reliable power sources like natural gas or coal-fired power plants. It’s the wiggle room the grid has to meet so it doesn’t fail.
California ISO, which operates a large part of California’s electric grid and is focused on future grid security, published a (now infamous among renewable energy nerds) graph of what the net load looks like today, and what it could look like in the future as California switches to a mandated renewable- and solar-reliant electricity system.
The concept is, with future energy storage capactiy, we could save and store electricity produced by solar panels when the sun is shining. We could then use that electricity at night. To see how this works, and why it is called flattening the duck, check out my Inside Energy report here.