Dynamic electricity tariff

Directive (EU) 2019/944 defines a dynamic electricity price contract in Article 2(15): a supply contract between a supplier and a final customer that reflects price variation in the spot markets, including the day-ahead and intraday markets, at intervals at least equal to the market settlement frequency. Article 11 lets every final customer with a smart meter request such a contract from at least one supplier and from every supplier with more than 200,000 final customers. The supplier must obtain the customer's consent before switching them to it and must explain the opportunities, costs and risks of each type of contract. For at least ten years after these contracts become available, member states or their regulators have to monitor them and publish an annual report on market developments, the impact on bills and price volatility.

Poland wrote these rules into the Energy Law (Prawo energetyczne, consolidated text Dz.U. 2026 poz. 43). Article 3(6d) defines the contract as one that reflects price changes on the day-ahead and intraday markets at intervals at least equal to the imbalance settlement period set under Regulation 2017/2195. Under Article 5(4f) to (4h), a customer with a smart meter can buy electricity on a dynamic price contract, a supplier with at least 200,000 end customers must offer one, and the contract needs the customer's consent. Article 5(4i) requires the power exchange to publish day-ahead and intraday prices at the imbalance settlement interval, in PLN per MWh to the nearest 0.01 PLN, and to pass them to suppliers as soon as they are set. An amendment published on April 15, 2026 (Dz.U. 2026 poz. 516) rewrote Article 5(4g): a supplier of that size now has to offer both a dynamic price contract and a fixed-term contract with a guaranteed fixed price, for 12 months and for longer. Before signing, the supplier must tell the customer whether the price is fixed, variable or dynamic, and what the price or the algorithm that sets it is.

In practice the price for each period is the exchange price for that period plus the supplier's margin and fees. Distribution charges are separate: the network operator still bills them under its own tariff, whatever the sales contract says.

A dynamic tariff moves the price from a contract field to a daily data feed. An EMS, a billing system or a customer app that works with it needs:

• A daily import of next-day prices in the resolution of the day-ahead market, which has priced every quarter-hour since October 1, 2025.
• An explicit time zone on every import. A one-hour shift in a CSV file moves every price into the wrong period, and the optimizer then charges at the wrong time.
• The supplier's formula. The customer's price is the exchange price plus margin, fees and taxes, and the sales tariff has to stay separate from the distribution tariff.
• Tariffs with validity dates per site. Customers change contracts, so statistics and forecasts must be recalculated when the tariff changes, or reported savings will be wrong.
• Savings calculated period by period: the energy shifted multiplied by the price difference in that period. A monthly average price hides most of the value.
• Negative prices handled as normal data in control logic, reports and invoices.
• A schedule ready before the delivery day starts, and a fallback for the day when the price feed is late.
• Interval data from a smart meter, which the contract requires and which settlement uses.

Since January 2024 we have built the EMS for Zeronest. It optimizes against the customer's sales tariff, dynamic or time-of-use. In October 2025 we fixed a CSV tariff import whose timestamps ran one hour ahead, which had forced users to shift every price in the file by an hour. In January 2026 each installation got a sales tariff chosen separately from the distribution tariff, in the prosumer app, the installer app and the web panel, and the platform started recalculating price statistics and predictions after every tariff change. By July 2026 the web platform showed tariffs at 15-minute resolution.