“How do we quantify the difference between renewable energy generated and energy demand?”
Renewable energy is now able to generate vasts sums of power in many parts of the world. However, it currently is not able to provide all of the power consumed by many parties. Because of this, renewable energy experts have called this difference to be the Net Load on the system. The Net Load tends to be lower at noon due to the availability of the sun (resulting in the infamous duck curve). California’s net load can be seen on this website.