The ERCOT BESS Index represents average battery energy storage revenues across a given timeframe.
In March 2024 (the last full month for which ERCOT market disclosure data exists), batteries listed on the Index made around $36,000/MW (annualized) on average.
![](https://images.storychief.com/account_26864/monthly-index_d41ac073716f64a5b1ba9bf5f1836a86_800.png)
These revenues were 39% lower than the same time last year.
![](https://images.storychief.com/account_26864/yoy-monthly-performance_1e019c05315085ecac85f3977912543e_800.png)
Head to this article to learn more about 2023 battery revenues.
64% of battery revenues in March came from Ancillary Services
In March 2024, battery energy storage systems earned 64% of revenues from Ancillary Service markets.
However, they earned more than one-third of their revenues from Energy arbitrage.
![](https://images.storychief.com/account_26864/as-donut_7e5d113d4476a1a0276f8ae6faa7d8da_800.png)
Historically, battery energy storage revenues have been dominated by Ancillary Services.
![](https://images.storychief.com/account_26864/as-bars_875f52b1818f9ac92328343e8ec0f3b3_800.png)
As operational battery capacity increases, these Ancillary Services will start to become saturated - pushing prices down.
As this happens, battery energy storage systems will generally earn a larger proportion of their revenues from Energy arbitrage.
In March 2024, revenues from Energy accounted for 36% of battery earnings - up from 22% of earnings last year in March 2023.
How does battery duration impact revenues?
Longer-duration battery energy storage systems (>1.5 hours) actually earned 56% of their revenues from Energy arbitrage. While shorter-duration batteries earned just 19% of their revenues from Energy.
Instead, shorter-duration batteries earned 36% of their overall revenues from the Responsive Reserve Service.
![](https://images.storychief.com/account_26864/duration-bars_f5aca691a2c8adf3251b814f7b89cad3_800.png)
This makes sense, given there’s no competitive advantage for two-hour systems in the service (due to its short response times).
However, two-hour batteries can discharge for longer during peak times. They can also enter a larger proportion of their capacity into longer-lasting Ancillary Services like ERCOT’s Contingency Reserve Service (ECRS) and Non-Spinning Reserve (Non-Spin).
This means that they can earn above-average revenues during periods when prices are less volatile, and revenue opportunities are more limited (like March).
On average, two-hour systems earned 62% higher revenues than one-hour batteries in March.
![](https://images.storychief.com/account_26864/duration-stacked-bars_6354d055d12dac7b1318bcc9dbe5d57d_800.png)
In fact, if we rank all batteries by $/MW revenues earned in March, the top eleven systems all had a duration of greater than 1.5 hours.
Which operational strategy was most lucrative for batteries in March 2024?
In March, batteries that carried out Energy-dominant revenue strategies earned 1.7x more revenue (on average) than batteries with Ancillary Service-focused strategies.