We’re pleased to share an updated chart that visualizes the historical stand-alone profitability of battery energy storage systems (BESS) across several European markets — now including Denmark DK1 and DK2, thanks to the recent expansion of our Clean Horizon Storage Index.

Key Takeaways:

As in previous editions, the color scale reflects profitability levels relative to a 15% IRR target:

• Red: monthly revenues below the threshold for 15% IRR over 15 years
• Yellow: revenues meet the 15% IRR threshold
•  Green: revenues are at least double that threshold

Each line on the chart represents a different European country: Poland, Spain, France, Germany, Sweden, and now Denmark DK1 and DK2.

Methodology:

1. For each country, we calculated the minimum monthly revenue required to achieve a 15% IRR over 15 years for a standard 100 MW / 2-hour BESS project.

2. We then analyzed monthly revenue data from Clean Horizon’s latest Storage Index publication (data through end of March 2025), available here: Storage Index.

3. The chart applies a simple color code based on actual vs. required monthly revenues, helping to visualize historical performance at a glance.

Notable Update:

This edition includes a revised view of Spain, now factoring in aFRR capacity payments — a change from last month’s chart. While whether BESS can consistently access this revenue stream remains debatable in practice, we opted to include it in this scenario to reflect evolving market assumptions.