​If you're in the business of battery energy storage, you need a clear, consistent way to benchmark potential revenue. That’s where Top-Bottom (TB) spreads come in. These spreads offer a powerful shorthand for understanding energy arbitrage opportunities in wholesale markets.

TB spreads are now available directly in the Modo Energy Terminal.

What are TB Spreads?

Top-Bottom spreads measure the difference between the x highest and lowest power prices in a day.

For example, a TB3 spread adds up the difference between the top three and bottom three hourly prices in a day. This gives a practical indicator of how much a battery could earn by shifting energy from troughs to peaks.

Impact of solar generation on TB spreads

​In volatile markets, the TB1 - the spread between the single highest and lowest hourly prices - can make up a significant portion of the arbitrage opportunity.

In Germany, for instance, extreme negative pricing (as low as -€300/MWh) during solar generation peaks makes its TB1 one of the highest in Europe. This happens because 90% of German solar energy is subsidized. This means it continues to generate even when prices fall below zero.

In Spain, solar penetration is nearly twice as high as Germany’s. However, only 30% of it is subsidized. Rapid solar deployment has led to a surge in €0/MWh prices over the last two years. However, prices rarely fall below zero, as most solar systems self-curtail to avoid losing revenue.

This creates long, flat troughs in daily power prices. As a result, the value of Spain’s TBs continues to rise beyond the TB5, while the value of Germany's and Great Britain’s diminishes more rapidly.

​Tracking arbitrage over time

​TB spreads describe current price shapes - but they can also show how arbitrage opportunities evolve over time.

In Germany and Spain, TB spreads have steadily increased over the last five years due to rising solar buildout and more negative or €0/MWh prices.

But in Great Britain, TBs peaked in 2021, before declining as peak-hour price spikes diminished. The TB1 in Britain has dropped 53% since 2021, despite more negative pricing.

But, does this mean battery revenues in Great Britain have followed TB spreads over the years?

​Energy arbitrage is growing

​Between 2020 and 2022 in Great Britain, when battery energy storage development was in its early stages, batteries earned around 90% of their revenue from ancillary services, such as frequency response, which aren’t reflected in TB spreads.

But as these markets became saturated, more batteries started trading energy and responding to price signals. Batteries now shift up to 2 GW of power from midday demand lows to evening peaks, responding to wholesale price signals.

Accuracy of TB spreads as a revenue index

​The growth in energy arbitrage means 65% of battery revenues now come from energy markets, such as the Balancing Mechanism and wholesale trading. In 2020, that figure was just 17%.

As a result, TBs are becoming a more accurate proxy for revenues in Great Britain. Between 2020 and 2022, one-hour batteries in GB occasionally earned 10 times more than the TB1, and at other times, 50% less.

​In 2025, the range of revenue uplift has reduced, with batteries earning between -50% and 300% of the TB1. On average, one-hour batteries now tend to earn around twice as much as the TB1, while two-hour systems earn roughly 42% more than the TB2. In other words, TBs are growing into a reliable index of performance.

Great Britain is one of the most mature battery markets in Europe. As newer markets, such as Spain and Germany, develop, a similar evolution of TB spreads and their relationship to real revenues is expected to emerge.

​Now available in the Modo Terminal

You can now explore Top-Bottom spreads across 12 European regions directly in the Modo Energy Terminal - with more markets on the way.

• Access TB spreads for both day-ahead and intraday markets
• See P10, P50, and P90 values for probabilistic insights
• Benchmark revenue potential by duration and location

Ready to dig deeper? Start with our TB explainer for US markets to see how the methodology applies across all markets.