Dynamic energy prices
Stekker optimizes charging moments based on real-time energy prices. Instead of a fixed rate per kilowatt-hour, Stekker follows fluctuating market prices and automatically schedules charging sessions when electricity is cheapest.
These prices come from two types of wholesale markets:
- Day-ahead market — Hourly prices published a day in advance through an auction. Around 11:00, prices for the following day become available. This is the primary market Stekker uses: the hourly prices determine when charging is most cost-effective.
- Intraday market — Prices traded on shorter timeframes, enabling more granular optimization. Stekker supports both hourly and quarter-hourly resolutions.
Using this market data, Stekker’s energy management system (EMS) automatically schedules charging sessions during the cheapest hours, taking into account your desired departure time and minimum charge level.
Supported markets
Stekker retrieves price data from multiple sources, depending on the country and market region:
ENTSO-E (European platform)
The European Network of Transmission System Operators publishes day-ahead prices for all of Europe. Stekker uses this as the primary source for European markets. Supported market areas include:
- Netherlands (NL)
- Belgium (BE)
- Germany + Luxembourg (DE-LU)
- France (FR)
- Austria (AT)
- Switzerland (CH)
- Denmark (DK1, DK2)
Prices are retrieved at hourly resolution (60 minutes) or quarter-hourly resolution (15 minutes), depending on the market configuration.
Nord Pool
As a fallback for European markets, Stekker also uses Nord Pool, the Scandinavian energy exchange. When ENTSO-E temporarily fails to deliver data, the system automatically switches to Nord Pool.
Octopus Energy (United Kingdom)
For the United Kingdom, Stekker retrieves prices via the Octopus Energy API, using the Agile Octopus tariff. This tariff operates with half-hourly prices (30 minutes) in British pounds (GBP). Prices for the next day are published daily around 15:00.
Automatic fallback
The system has a built-in fallback chain: if the primary source (ENTSO-E) is unavailable, it automatically tries Nord Pool, followed by NieuweStroom as a last resort. This guarantees maximum availability of price data.
Tariff types in Stekker
Each site is configured with the applicable tariff type. Stekker supports three models:
Dynamic tariff
Hourly prices directly from the energy market. Stekker links your site to the appropriate market based on your country and region. The EMS schedules charging sessions during the cheapest hours of the day. This typically yields the greatest savings.
Fixed tariff
A single constant price per kilowatt-hour, regardless of the time of day. In this case, Stekker does not optimize for price advantage, but can still optimize for other factors such as grid congestion or solar production.
Time-of-use tariff
Multiple tariff zones based on a time schedule. A common example is a dual tariff with a peak rate during the day and an off-peak rate at night. Stekker supports flexible schedules: you configure the start and end time for each tariff zone, and whether weekends are excluded. The system schedules charging sessions in the cheapest tariff zone whenever possible.
Imbalance market
In addition to the regular energy markets, Stekker can also respond to the imbalance market. This is an optional feature that is enabled per site.
What is the imbalance market?
TenneT, the Dutch transmission system operator (TSO), is responsible for the balance between supply and demand on the electricity grid. When more electricity is produced than consumed (or vice versa), an imbalance occurs. TenneT publishes real-time imbalance prices that indicate whether the grid has a surplus or deficit.
How Stekker responds
Stekker compares the current imbalance price with the day-ahead market price. Based on the difference, the system sends a signal:
- Grid surplus (imbalance price significantly lower than day-ahead) — Stekker increases charging power. Electricity is extra cheap at that moment, and charging helps stabilize the grid.
- Grid deficit (imbalance price significantly higher than day-ahead) — Stekker reduces charging power. This avoids charging at expensive moments and relieves the grid.
- Normal situation — No adjustment; the regular charging schedule is followed.
The system uses a threshold: adjustments are only made when the difference exceeds EUR 100 per MWh. This prevents unnecessary switching during small price fluctuations.
Additional savings
Imbalance optimization can deliver additional savings on top of the regular day-ahead optimization. The feature is optional and is configured per site by the Stekker team.
Configuring your tariff type
The tariff type is configured per site in Stekker. When setting up a site, you choose from the three tariff types:
- Dynamic — Stekker automatically links to the appropriate energy market for your country and region. You do not need to select a market yourself.
- Fixed — Enter your fixed kilowatt-hour price.
- Time-of-use — Configure the tariff zones with start and end times and the corresponding prices.
Do you have a dynamic energy contract with your supplier? Then choose the dynamic tariff type. Stekker uses the same wholesale prices as your supplier and schedules charging sessions when the price is lowest.
