Bloc + Spot Power Contracts: 2026 Supermarket Strategy

Remi BouteillerApr 28, 2026

ARENH died on 31 December 2025. With it, the safety net at EUR 42/MWh that had cushioned every French B2B power contract since 2011. For grocery retail, where a hundred-store chain runs through 200 to 400 GWh a year, this is not a paperwork change. It rewrites the bill.

The market sets the pace. The French spot price hit EUR 81/MWh on 27 April 2026, with a 30-day average around EUR 91/MWh. Cal-2026 baseload trades at EUR 58/MWh, Cal-2027 at EUR 49/MWh. Three prices, three curves, and an energy buyer who must pick where to place their money.

The increasingly dominant answer inside French retail energy desks has a name: the bloc + spot contract. A hybrid structure that locks in 70 to 80% of the volume on forward markets, and lets the remaining 20 to 30% float on EPEX at the hourly day-ahead price. The bet? Capture the dips, smooth the spikes, and beat a 100% fixed contract by EUR 5 to 10/MWh.

Key Takeaways

The French average spot price was EUR 61/MWh in 2025 (vs EUR 58/MWh in 2024), with 513 hours of negative prices and 1,807 hours above EUR 100/MWh (RTE / Selectra, 2026)

ARENH ended on 31 December 2025 and the new Versement Nucléaire Universel (VNU) only triggers above EUR 78/MWh: CRE estimates EDF's 2026 nuclear revenue at EUR 65.86/MWh, so no redistribution is expected this year (EDF Entreprises, 2025)

Bloc + spot blends 70 to 80% of secured volume via forward blocs (Calendar, Quarter, Month) with 20 to 30% indexed on EPEX day-ahead, dropping the supplier risk premium versus a 100% fixed contract (Capitole Energie, 2026)

The historical 10 GWh/year access threshold now drops to 1 GWh through purchasing pools, opening the strategy to independent supermarkets and franchisees (Capitole Energie, 2026)

Energy trading desk showing forward bloc grid and spot market wave, retail procurement view

What Is a Bloc + Spot Contract?

A bloc + spot contract buys electricity for your portfolio in two parts. The first, called "bloc", locks a fixed price upfront for a fraction of forecast consumption through standard forward products: Cal-2026 baseload (24/7 over the year), peakload, quarterly blocs (Q1, Q2…), monthly blocs. The second, called "spot", pays the EPEX day-ahead price every hour (Engie B2B, 2025).

The standard split among industrial buyers and mature C&I procurement teams is 70 to 80% bloc and 20 to 30% spot (Opéra Energie, 2025). This proportion stabilises the budget on most of the volume while keeping a window open for off-peak hours, sunny weekends, and the increasingly frequent negative-price episodes.

For a hypermarket consuming 3 GWh per year, that translates into 2.1 to 2.4 GWh bought at a price set in stone, and 600 to 900 MWh exposed to the hourly market. The result is more stable than 100% spot, more competitive than 100% fixed, and far more steerable.

Our take: Bloc + spot is not a product, it is a discipline. A passive buyer who signs 80% bloc and forgets the contract captures very little value. The edge appears when the buyer adjusts blocs quarter by quarter, buys more forward when the curve dips, and uses on-site flexibility to shed during expensive spot hours. Bloc + spot rewards active buyers, not subscribers.

The price logic stacks in three components. The bloc share reflects forward-market expectations: EUR 58/MWh on Cal-2026, EUR 49/MWh on Cal-2027 (Optima Énergie, 2026). The spot share follows the actual physical system hour by hour. And the final invoice adds non-energy components (TURPE network fee, electricity excise tax, capacity contribution), which do not depend on the bloc-or-spot decision.

Why Does 2026 Change the Game for Buyers?

For 14 years, ARENH set an implicit ceiling on every B2B power contract. Alternative suppliers bought up to 100 TWh/year from EDF at the regulated EUR 42/MWh price, and passed it through into their offers. The scheme ended on 31 December 2025 (EDF Entreprises, 2025).

The replacement, the Versement Nucléaire Universel (VNU), is not a new ceiling. It is a redistribution mechanism: EDF keeps 100% of its revenue below EUR 78/MWh, returns 50% between EUR 78 and EUR 110/MWh, and 90% above (Enercoop, 2025). For 2026, CRE estimates EDF nuclear revenue at EUR 65.86/MWh, below the first threshold. No redistribution is expected this year. The safety net exists, but it sits high.

In practice, the 2026 buyer faces a freer, more volatile market, with price formation now fully dependent on forwards and spot. That is exactly the terrain bloc + spot was designed for.

The 2027 horizon adds an upside note. Cal-2027 baseload trades around EUR 49/MWh, EUR 9 below Cal-2026 (Acieb Énergie, 2026). A buyer who locks in Cal-2027 blocs now while keeping a spot share captures that anticipated drop, and stays exposed to occasional spot dips.

How Much Bloc, How Much Spot?

The empirical rule across grocery retail sits between 70/30 and 80/20, with a dominant bloc share. Below 60% bloc, the bill becomes too sensitive to winter spot spikes. Above 90%, you lose the upside from negative-price hours and sunny weekends.

The consumption profile drives the trade-off. A supermarket opens early, ramps to peak around midday, dips in the afternoon, and ramps again until closing. That curve maps reasonably well onto baseload at night (refrigeration runs continuously) and onto peakload during the day (registers, lighting, HVAC). An optimised hedge therefore mixes 50 to 60% Cal-2026 baseload for the 24/7 floor, 10 to 20% peakload for the trading-hour spike, and 5 to 10% quarterly blocs for seasonal swings (summer cooling, winter heating). Spot picks up the residue.

2025 illustrates the stakes. RTE counted 513 hours of negative spot prices (vs 359 in 2024) and 1,807 hours above EUR 100/MWh (Selectra, 2026). A 100% spot buyer saw their price swing from -EUR 50/MWh to +EUR 600/MWh depending on weather. A 100% fixed buyer paid a risk premium to avoid that ride. A bloc + spot buyer captured the bulk of the stability and went after residual value on solar-heavy spring weekends.

Our take: The spot share of a bloc + spot contract should always be larger than the demand response capacity available across the portfolio. If you have 500 kW of pilotable load on a store and your spot exposure is 200 kW, you leave 300 kW of arbitrage capacity idle. Counter-intuitive flip of the usual logic: flexibility unlocks the spot share, not the other way around.

How Much Can It Actually Save?

The gap between a 100% fixed contract and a 75/25 bloc + spot in 2025 ran at EUR 5 to 10/MWh among most publicly disclosed C&I buyers (Capitole Energie, 2026). For a chain consuming 300 GWh/year, that is one hundred stores worth of EUR 1.5M to EUR 3M annual savings. The math rests on three sources of gain.

1. Avoided risk premium. A supplier who commits to a 100% fixed price for 12 or 24 months has to absorb market uncertainty. That uncertainty is monetised through a premium on top of the forward, typically EUR 5 to 8/MWh. By signing bloc + spot, the customer takes the risk back and saves the premium (Collectif Énergie, 2026).

2. Forward arbitrage. When the Cal-2026 curve drops mid-year (it slid from EUR 59 to EUR 58/MWh during 2025), an active buyer arbitrages. They can lock another bloc at the new level, or wait for a deeper drop. A 100% fixed buyer is stuck on the initial price. Across a year, those arbitrages capture EUR 1 to 3/MWh.

3. Spot capture on favourable hours. In 2025, France saw 513 hours of negative prices and around 1,800 hours below EUR 50/MWh. A 25% spot consumer pays a meaningfully lower average than the annual mean simply because their consumption curve overlaps partially with favourable hours. For a 7-day-a-week supermarket, the net spot gain reaches EUR 2 to 4/MWh.

Refrigerated cabinets with smart meter and dashboard, operational view of a supermarket energy buyer

The risk is real. If the winter is cold and spot averages EUR 80/MWh against EUR 50/MWh on bloc, the spot share costs EUR 30/MWh more than the bloc, or EUR 7.5/MWh on the 75/25 mix. The expected gain disappears. That is exactly why no serious buyer goes above 30% spot without operational flexibility to push consumption from expensive hours to cheap ones. Bloc + spot and physical flexibility are two faces of the same strategy.

What we see in the field: Buyers who get the best results on bloc + spot consistently run two tools in parallel: hourly consumption tracking, and an active demand response or load-shifting program. Without those two pieces, the spot share becomes a passive trader who absorbs spikes instead of avoiding them.

For chains who want to size their spot exposure against their pilotable potential, our supermarket demand response guide explains how to quantify activatable flexibility per site.

What Infrastructure Makes Bloc + Spot Work?

Three prerequisites turn a bloc + spot contract from a financial product into an operating lever: hourly consumption tracking, a physical flexibility strategy, and a clear procurement governance. Without those three, bloc + spot is a defensive saving. With them, it is an offensive margin.

1. Hourly tracking. A bloc + spot contract is not steered with a monthly invoice. You need to see the consumption curve per site per hour, compare it to the purchased blocs, and measure the deviation from the planned profile in real time. Our energy tracking guide covers how to set this up.

2. Physical flexibility. The higher the spot share, the larger the value of avoiding expensive hours. A store that can shift 200 kW of refrigeration from 6pm to 10pm captures a spot saving on top of the RTE demand response revenue. Thermal load shifting and grid demand response stack.

3. Governance. Many chains hand power procurement to a purchasing team that approves once per year. A bloc + spot contract demands a quarterly cadence at minimum: review the bloc/spot allocation, trigger new blocs on curve drops, adjust the seasonal profile. Without that discipline, the value evaporates.

The historical 10 GWh/year access threshold now drops to 1 GWh through purchasing pools, opening the strategy to standalone supermarkets and franchisees (Capitole Energie, 2026). A 2,000 m² Carrefour Market or an Intermarché Express now qualifies for a structured contract, where five years ago only an 8,000 m² hypermarket could.

To combine structured procurement with grid-side flexibility revenue, see our automated demand response page for supermarkets: RTE demand response and bloc + spot run on the same physical levers (refrigeration, HVAC, lighting), with additional revenue and zero new capex.

Frequently Asked Questions

What is the difference between a spot-indexed contract and a bloc + spot contract?

A 100% indexed contract follows the EPEX day-ahead price every hour, with full exposure and maximum volatility. A bloc + spot locks 70 to 80% of the volume on secured forward prices and only exposes the residual to spot. Bloc + spot delivers fixed-contract stability on most volume, with indexed-contract upside on the margin.

What consumption do I need to sign a bloc + spot?

Historically reserved for sites consuming above 10 GWh/year, bloc + spot is now accessible from 1 GWh/year through purchasing pools or specialised aggregators. A 50-store chain can therefore structure a contract even if every individual site is below the threshold.

What happens if I consume more than the bloc volume?

The gap between actual consumption and bloc volume is settled at the hourly spot price. If you secured 80% of your forecast and you consume 105% of the volume, the 25% gap clears at spot. A good forecast (built on hourly historical data) keeps that gap below 10%.

Do I need an in-house trader to run a bloc + spot?

No. Most suppliers (Engie B2B, EDF Pro Premium, Total Direct Energie, GreenYellow) and brokers (Opéra Energie, Capitole Energie, Eneffic) offer an arbitrage service that executes blocs against an agreed policy. The customer's role is limited to validating a quarterly strategy.

Could VNU make 100% fixed more attractive than bloc + spot?

Not in 2026, where CRE estimates EDF revenue at EUR 65.86/MWh, below the EUR 78/MWh threshold that would trigger redistribution. If market prices were to climb meaningfully above EUR 78/MWh for several consecutive quarters, a partial VNU would mechanically cushion both fixed contracts AND forward blocs. The relative logic between fixed and bloc + spot stays intact.

Your Energy Has Become a Financial Asset. Manage It Like One

ARENH is gone, the spot market is volatile again, and forward Cal-2026 and Cal-2027 are showing EUR 5 to EUR 9 drops that active buyers can capture. For grocery retail, where 200 to 400 GWh per year flows through the meters, every saved euro per MWh adds up to millions.

Bloc + spot is not a sign-and-forget product. It is a procurement discipline that delivers EUR 5 to 10/MWh when properly run, and zero when neglected. Chains that pair a quarterly-adjusted bloc + spot with a piloted demand response program capture both sides of the market: the forward drop via blocs, the spot value via flexibility.

To start, build hourly site tracking with our energy tracking guide, then size your activatable flexibility on the supermarket demand response side. Bloc + spot becomes an obvious decision once those two pieces are in place.