So how much will you need to rely on your generator? You can start by estimating the system’s expected energy production at the location’s average daily sun-hours, and then look at the times of year when you’ll be short, due to higher consumption and less sun. Once you have an idea of how much energy you’ll need to make up, you can estimate the generator run time. Changing weather and consumption patterns make estimating this a moving target, but this process will give the designer an idea of when during the year the generator will run and for how long—and may prompt the designer to suggest additional load-shifting and efficiency measures for these times.
