The autarky level – also called degree of self-sufficiency – shows what percentage of your total electricity demand you cover with solar power or other electricity you produce yourself, directly or via the battery.
It shows how independent you are from the grid. You still draw the rest from the grid.
How the autarky level is calculated
Autarky level = (direct self-consumption + battery consumption) / total consumption × 100 %
Direct self-consumption: solar power used in the same time step it is produced.Battery consumption: solar power that is first stored and later used from the battery.Total consumption: the electricity demand of all consumers in the tab – household,
Heating system,Wallbox / EV,Air conditioningand custom consumers.
autarc calculates all values for every time step of the year – hourly or at the selected Simulation resolution – and then adds them up over the whole year. More in Energy flows.
Example
A household with a heat pump uses 5,000 kWh a year. 2,000 kWh of it are covered directly by solar power and 1,000 kWh from the battery. The remaining 2,000 kWh come from the grid.
Autarky level = (2,000 + 1,000) / 5,000 × 100 % = 60 %
Why the annual value isn't an average of the months
The annual value is the sum of direct and battery consumption over all time steps divided by the sum of consumption. A simple average of the monthly values would be wrong: in summer the autarky level is high, in winter – with little sun and often high heat pump consumption – it is low. The sum method weights each month by its actual consumption.
What counts towards the autarky level?
Custom producers only if you choose: by default only the solar system counts. If you turn on
Include in KPIsfor a custom producer (e.g. a wind turbine), it counts too: the part of consumption it covers directly or via the battery then raises the autarky level.No grid power from the battery: if the battery also charges cheap grid electricity with the control scheme
Tariff arbitrage, that electricity doesn't count towards the autarky level when discharged – it was only shifted in time, not produced on site.All consumers: a new heat pump or wallbox increases total consumption. The autarky level can therefore drop, even though more solar power is used on site.
Why is 100 % hardly achievable?
At night and on dull winter days, the solar system produces little or no electricity. Even a large battery can't shift solar power from summer to winter. In single-family homes, typical values are around 25–40 % without a battery and around 50–75 % with a battery.
Autarky level and self-consumption rate
The autarky level refers to consumption: how much of your electricity demand does the solar system cover?
The self-consumption rate refers to generation: how much of the solar power do you use yourself?
A larger system usually raises the autarky level but lowers the self-consumption rate.