Glossary
Tertiary control reserve (TRL)
Also known as: Tertiärregelleistung, TRL, TRE, Tertiärregelenergie, Minutenreserve, mFRR, Manual Frequency Restoration Reserve, Minute reserve
Tertiärregelleistung (tertiary control reserve, TRL) is the third tier of control reserve: Swissgrid activates it manually when an imbalance in the Swiss electricity grid lasts longer than 15 minutes, relieving secondary control reserve. In 2025, Swissgrid procured around 500 MW of positive and around 430 MW of negative tertiary control reserve on annual average (ElCom). From mid-2026, the minimum bid falls to 1 MW (Swissgrid Balancing Roadmap). Through a pool, PV systems without storage can also offer capacity in this market.
As with secondary control reserve, Swissgrid separates holding capacity (TRL+ and TRL-) from activation (TRE+ and TRE-). Activation is not triggered automatically by grid frequency but by Swissgrid’s dispatchers when an imbalance persists. The growth in activated balancing energy from around 700 GWh in 2020 to around 1’160 GWh in 2025 took place mainly in tertiary balancing energy (ElCom).
For businesses with a PV system, tertiary control reserve is the entry into the balancing energy market without storage: a modem in the distribution board connects the system to a pool, which curtails feed-in on activation. Ampere Dynamic calculates up to CHF 15’000 per MW and year for this (Ampere Dynamic model estimate, 2026, indicative only); for comparison, holding secondary control reserve cost Swissgrid around CHF 70’000 per MW on average in 2025 (ElCom).
The process from pooling contract to registration is described in the article Balancing energy with battery storage. Market access runs through a pool as part of our energy marketing.