They chose an 8.1 kW DC system that produces approximately 9,400 kWh per year. In other words, their system can generate as much, or more, electricity than their household consumes annually.
Like many families, their consumption is higher in the colder months, around 850 kWh per month from November through February, and lower in summer, closer to 600 kWh in July. Solar production follows the opposite pattern. Most electricity is generated between March and September, with the highest output in June, July, and August.
This creates balance by building credits during summer surpluses, which then cover the gap in winter when consumption rises and solar production slows down.