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How can you predict your electricity bill based on your consumption?
In short. For an industrial site on a block + spot contract, predicting your electricity bill means knowing how much each MWh consumed at a given time will cost, all components included: blocks, spot, grid tariff (TURPE) and capacity. Without a dedicated tool, a site only knows the spot price the day before for the next day, and tracks its TURPE reduction by hand. With Highcast, it gets a single indicator of electricity cost over time, continuous tracking of its TURPE reduction and price forecasts up to 14 days ahead.
What makes up an industrial site’s electricity bill?
This article is for industrial sites on a block + spot contract: part of their electricity is bought in advance at a fixed price, the rest at market price. Their bill adds up four components, which do not vary in the same way with consumption:
- Blocks: the volumes bought in advance at a fixed price. Their cost is known as soon as they are purchased.
- Spot: the gap between your actual consumption and your blocks, bought or sold back at market price, quarter-hour by quarter-hour.
- TURPE: the French grid access tariff. For large sites connected to the transmission grid, it can be heavily reduced, provided the site meets a specific consumption profile over the year.
- Capacity: the cost of the mechanism that guarantees security of supply. It depends on your consumption during winter peak days.
Blocks are fixed. The other three components depend on when you consume. That is what makes the bill hard to predict.
Why is it so hard to forecast your bill without a tool?
Without a dedicated tool, an industrial site on a block + spot contract manages its bill with less than 24 hours of visibility and spreadsheets filled in by hand. Four obstacles come up at most sites.
The spot price is only known the day before. RTE provides the next day’s price between 1:30 pm and 2 pm, but through API requests, which require a technical integration. On its éco2mix platform, the same data tends to appear at the end of the day: operational teams who check the website often only see it then. Either way, it comes too late: most suppliers ask for next-day consumption forecasts by late morning. By the time the price comes out, the schedule has already been sent and cannot take it into account. Under these conditions, it is impossible to place production in the cheapest hours, let alone the following week.
Peak days are announced at the last minute. Since 1 November 2026, RTE, the French transmission system operator, can designate up to 22 peak days between November and March, covering the 7–10 am and 5–8 pm slots. Your consumption during these slots sets your share of the capacity cost, but these days are signalled between three days before and 7 pm the day before, as part of an orange or red EcoWatt alert. A late announcement therefore arrives after consumption forecasts have been sent to the supplier.
The TURPE reduction is tracked by hand. For a site connected to the transmission grid and consuming more than 10 GWh a year, the reduction reaches 74% for a counter-cyclical profile, provided the site has an off-peak grid utilisation rate of at least 44%. For a stable profile, it reaches 81% with at least 7,000 hours of grid utilisation. At most sites, this tracking is still done by hand in a spreadsheet: a gap is often discovered too late to be made up, putting the whole year’s reduction at stake.
No indicator shows the total cost. Between fixed blocks, the spot price, TURPE-related costs and the capacity mechanism, the real cost of electricity is scattered across several sources that need to be consolidated. No one can see, at any given moment, how much the next MWh consumed will really cost.
What difference does a single electricity cost indicator make?
Highcast combines the four components of the bill into a single indicator: the real cost of electricity, in €/MWh, hour by hour, for the power you plan to draw.
For each time slot, this indicator adds up:
- the share covered by your blocks, at their purchase price;
- the share above or below your blocks, valued at the forecast spot price;
- the effect on your TURPE and on your reduction trajectory;
- any extra cost from a peak day.
In practice, a production manager can compare two options before deciding: run a 5 MW campaign on Tuesday afternoon, or move it to Thursday night. They can see straight away which one costs less, all components included, rather than comparing spot prices in isolation.
How can you track your TURPE reduction continuously?
Highcast continuously calculates where your site stands against its reduction criterion, and what remains to be done by the end of the year.
For a site with a counter-cyclical profile, Highcast builds a reference consumption profile: the one that achieves an off-peak grid utilisation rate of 44%. It then continuously compares the site’s actual consumption with this profile and shows the remaining margin: how many MWh can still be consumed during peak hours without losing the reduction. For a site with a stable profile, the same tracking applies to grid utilisation time and the 7,000-hour target.
This tracking changes the nature of decisions. A trade-off between a cheap peak hour on the spot market and meeting the TURPE criterion is settled with figures, when it arises, not by discovering the result on the year-end bill.
Why does a 14-day price forecast change planning?
Highcast forecasts spot prices up to 14 days ahead, where official data stops at the next day. This horizon matches that of industrial planning.
A production schedule is built week by week. Maintenance is prepared several days in advance, with teams and subcontractors to mobilise. With 24 hours of visibility, none of these decisions can take the electricity price into account. As the manager of an industrial gas production site told us: “Right now, I have no visibility beyond twenty-four hours, and that’s a real handicap for me.”
With 14 days of visibility, trade-offs become possible:
- scheduling a maintenance shutdown on the most expensive days, to avoid consuming when each MWh costs the most;
- grouping energy-intensive campaigns on the cheapest days of the following week;
- anticipating tight periods in winter, even before peak days are officially announced.
Without or with Highcast: what does the tool actually change?
Frequently asked questions
When is the next day’s spot price known?
The next day’s price is available through RTE’s API between 1:30 pm and 2 pm, for each quarter-hour of the following day, and usually at the end of the day on the éco2mix platform. It therefore often arrives after consumption forecasts have been sent to the supplier. Beyond the next day, there is no official price: only forecasts make it possible to anticipate.
What are the criteria for the TURPE reduction?
The site must be connected to the transmission grid and consume more than 10 GWh a year. It must then meet a profile: an off-peak grid utilisation rate of at least 44% (counter-cyclical profile, 74% reduction) or at least 7,000 hours of grid utilisation (stable profile, 81% reduction).
How do peak days affect the bill?
Since 1 November 2026, the cost of the capacity mechanism is allocated according to consumption during peak days, in the 7–10 am and 5–8 pm slots. RTE can designate up to 22 of them each winter, announced between three days before and 7 pm the day before, as part of an orange or red EcoWatt alert.
Can electricity prices be forecast more than one day ahead?
Yes, with a forecasting model. Highcast forecasts spot prices as well as the total cost of electricity up to 14 days ahead, the horizon of a production schedule or a maintenance shutdown.
Summary
Predicting your electricity bill means knowing the real cost of each MWh before you consume it. Without a tool, a manufacturer on a block + spot contract has less than 24 hours of visibility and four scattered pieces of information. With Highcast, they see the total cost hour by hour, track their TURPE reduction continuously and plan 14 days ahead.
Want to see what this indicator would look like for your site? Contact us for a demo on your own data.
Sources
- EDF, “Le mécanisme de capacité en questions” (in French), 18 September 2026.
- RTE, “Signaux PP” (in French), data published by RTE on peak days.
- Opéra Énergie, “Réduction du TURPE : quels changements sont validés par la CRE ?” (in French), based on the CRE’s opinion on the 2021 decree.
- Testimonial: Highcast discussion with a manufacturer, anonymised.
