The degree of self-sufficiency indicates how independent a household or system is from external electricity sources, such as the public power grid, or, in other words, the percentage of your electricity demand that is covered by solar power.
The degree of self-sufficiency is expressed as a percentage and is calculated as follows:
Degree of self-sufficiency (%) = ( Σᵢ₌₁¹² ( Self-consumptionᵢ / Consumptionᵢ × 100 ) ) / 12
Self-consumption = Generation − Feed-in
In contrast, the self-consumption rate (or self-consumption share) describes what percentage of the self-produced PV electricity is used by the producer themselves.