Weekly Energy Storage Insights

Welcome back to another data-driven deep-dive into energy storage market dynamics for BESS operators and developers.

This Week: August's Real-Time TB2 Collapse

We called it early in August, and the final numbers confirm our concerns. Real-time TB2 spreads closed at just $3.45/kW-month; only the second time since 2019 we've seen spreads drop below $8.90/kW-month. For ERCOT battery operators counting on arbitrage as their primary revenue source, August was brutal.

The Year-Over-Year Impact

Here's what makes this particularly interesting: over the past five years, August typically delivered 20% of total annual real-time arbitrage opportunities, whereas this year that same number is at a paltry 9%.

So what exactly caused this collapse?

August in ERCOT usually means extreme heat and peak demand pressure. But August 2025 saw only a handful of triple-digit temperature days compared to the relentless heat of 2023 and 2024. The combination of mild weather and significant capacity additions since 2023 - particularly solar and storage—meant the grid handled demand with far less stress.

The bigger picture: 2025 summer spreads look weak not because of any systemic change. The rest of the year has tracked 2024 nearly identically. August alone dragged down the seasonal average. It is worth watching whether this becomes a new pattern or remains an outlier, especially with RTC+B changes coming soon to ERCOT.