For years, the average price of electricity was the main benchmark for assessing energy costs, planning investments and measuring the profitability of assets. However, the evolution of the electricity system is changing this logic. Today, the determining factor is no longer the average market price but the difference between the most expensive and cheapest hours of the day.

The expansion of renewable energies, especially solar photovoltaic energy, is profoundly changing the behaviour of electricity markets. It is increasingly common to observe hours with abundant renewable generation and very low prices followed by periods in which demand increases and prices rise sharply.

Spain is a clear example of this trend. In May 2025, the average price of the daily market reached €16.93/MWh, one of the lowest records in recent years.

However, this figure alone does not reflect the full complexity of the system. Behind these historically low prices lies a phenomenon with a growing impact on consumers and investors. This is the increase in intraday volatility, where some hours record minimum values while others maintain higher prices, widening the difference between both extremes. This is precisely where one of the greatest opportunities of the new energy system emerges.

The electricity spread measures the difference between the highest and lowest market prices within the same period. The greater this difference, the greater the potential to optimise energy consumption and generate savings. In 2025, this differential reached an average of €98/MWh, an increase of close to 40% compared with the previous year. During 2026, spreads continue to stand at high levels, around €91/MWh.

Far from being a temporary phenomenon, these differentials will continue to form a structural part of the market. The massive incorporation of new renewable capacity, the progress of electrification in sectors such as industry, mobility and heating and cooling, together with external factors such as gas prices or costs associated with CO₂, will continue to generate episodes of high volatility.

Flexibility as a new strategic asset

In this context, traditional energy strategies are losing effectiveness. Managing energy is no longer simply about consuming less or negotiating better supply contracts. The real challenge lies in optimising when energy is consumed, when it is stored and when the available energy is used.

Batteries are set to play a leading role in this new scenario. Their ability to store electricity during lower-cost hours and use it when prices are higher makes it possible to directly capture the value generated by spreads. The greater the difference between both moments, the greater the economic potential of these arbitrage strategies.

The experience developed by Edison Next in industrial projects shows that a battery with 1 MW of power and 2 MWh of capacity, installed behind the meter, can generate annual savings of up to €64,000 solely through arbitrage operations in the daily market.

Beyond economic savings, storage provides greater control over energy costs and improves organisations’ resilience in scenarios of high uncertainty.

Flexible demand: an immediate opportunity

However, flexibility does not depend exclusively on storage. Many companies have a still underused source of value, the ability to adapt their energy consumption to market signals.

Flexible demand management makes it possible to shift certain processes to the hours when energy is more abundant and economical. This ability to adapt can generate significant benefits without the need for major investments.

For example, a facility capable of shifting 1 MW of consumption for two hours a day can achieve annual savings of more than €42,000 by taking advantage of current hourly differentials.

In addition, the economic potential of flexibility continues to grow. Both storage systems and flexible demand will be able to complement revenues derived from arbitrage by participating in flexibility markets, balancing services, demand response mechanisms and future capacity markets.

From energy consumption to active energy management

This evolution shows that the electricity market is moving from a model focused on energy towards another in which flexibility has an increasingly relevant value. In an environment marked by volatility, spreads are no longer a simple consequence of the energy transition but a business opportunity.

Organisations capable of adapting their consumption, incorporating storage and actively managing their energy will be better positioned to reduce costs, generate new revenue streams and increase their competitiveness. In the new energy system, flexibility is no longer a complementary option but a strategic tool to capture value and build long-term resilience.