Technical explanation
Natural production/consumption overlap: 20–35%. With EMS + shift usages to 10h–16h: 40–55%. With 10 kWh battery: 60–80%. The economic optimum in Switzerland (low injection tariff) is TAC 40–60%.
Definition · Finance & ROI
Self-consumption rate% of solar production consumed on site
TL;DR
TAC = % of your self-consumed solar production. The Swiss economic optimum: 40–60% without battery, 60–75% with 10 kWh battery. Beyond 80%, the marginal ROI of the additional battery becomes > 20 years.
Definition
TAC = Self-consumed energy / Total energy produced × 100. Complementary to the autarky rate (which measures the coverage of your consumption).
☀️
Without battery
25–40%
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With EMS
40–55%
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With battery 10 kWh
60–75%
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Optimum eco. CH
40–60%
Swiss context
Going from 70% to 90% TAC requires a 2x larger battery for a marginal gain — ROI > 20 years on this additional investment. The monitoring app (FusionSolar, SolarWeb, Enlighten) displays your actual TAC.
Related terms
Related guides
FAQs — Self-consumption rate
Is it worth aiming for self-consumption 90%?+
Rarely. Reaching 90% from 70% requires a much larger battery for a marginal gain whose ROI often exceeds 20 years. The economic optimum is around 60–70%.
How do I measure my actual TAC?+
Via your inverter's monitoring app: Huawei FusionSolar, Fronius SolarWeb, Enphase Enlighten — all display the TAC in real time and historically.
Sources & method
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