What is the Storage Index?

The Storage Index is calculated monthly and represents the annualised revenue of a storage asset based on the real energy, capacity and ancillary services prices observed during this month. In other words, the computed value assumes that the year consists of 12 repetitions of the same month: the Storage Index thus provides accurate information about how the given month’s prices impact the revenue of a storage asset.

How is it computed?

The Storage Index is calculated using COSMOS, Clean Horizon’s sophisticated energy storage simulation tool. For more information about COSMOS, please visit our web-page about COSMOS or contact our sales team at sales@cleanhorizon.com.

The Storage Index calculation considers the following parameters:

• Round trip efficiency (measured at grid connection point): 85%
• Cycles: 1.5 cycles per day (Clean Horizon’s reference cycling constraint)
• Prequalification requirements tailored to each market and country and based on Clean Horizon’s expertise
• Perfect foresight for Day-Ahead (D-1) auction markets (e.g. FCR, aFRR reservation, day-ahead market)
• Imperfect foresight for other markets (e.g. aFRR energy, and mFRR energy)

The Storage Index is based on historical market data for each month. This data automatically collected by Clean Horizon ensuring that the revenue calculations reflect realistic operating conditions.

Which revenue streams are currently considered for each country?

• France: Revenues are calculated based on participation in the Day-Ahead market, Intraday (both auction and continuous), FCR, aFRR, mFRR and the Capacity Mechanism.
• Germany: Revenues are calculated based on participation in the Day-Ahead market, Intraday (auction and continuous), FCR, and aFRR.
• Spain: Revenues are calculated for participation in the Day-Ahead market and mFRR. aFRR is excluded due to unclear participation rules. Intraday is also omitted as it is considered not liquid enough.
• Poland: Revenues are calculated based on participation in the Day-Ahead market, FCR Up and Down, aFRR and mFRR.

How often is the Storage Index published?

It is updated every month.