Comparing Grid Tariffs for District Heating Heat Pumps
– A Simulation-Based Analysis of Network Connection Types
Written by Jonas Sønder Nielsen and Adam Mark Berman · 21. May 2025
Why Read This Article?
With rising electricity costs, the electrification of heat, and the increasing role of heat pumps in district heating systems, choosing the right grid connection can significantly impact annual operating costs. This article compares four different Danish electricity grid tariffs: B-lav, B-høj, A-lav, and A-høj, for a district heating system with a large heat pump and accumulation tank. The results provide insights into how grid connection affects operational costs and peak demand exposure. Simulations are done using CleanDesign and hourly 2024 electricity spot prices.
Introduction
District heating utilities face the dual challenge of reducing carbon emissions and maintaining low heat prices. Large-scale heat pumps are emerging as a key solution, and their economic performance is strongly influenced by the final electricity price. Danish grid tariffs vary widely by connection size and voltage level, with differences in energy-based tariffs, peak charges, and subscription fees.
In this article, we evaluate four common Danish tariff groups: B-lav, B-høj, A-lav, and A-høj, and quantify their effect on the operating costs of a typical district heating plant using a heat pump and thermal storage.
Simulation and Method
The system is modelled in CleanDesign with hourly resolution for the entire year of 2024. The setup includes a 6 MW heat demand profile, with the heat pump providing 80% of the maximum load and an electric boiler supplying the rest. A 2000 m³ accumulation tank is used to shift electricity consumption in time.
System Configuration:
- Max demand: 6 MW / approximately 22,000 MWh per year
- Heat pump capacity: Approximately 5 MW
- Electrical boiler capacity: 10 MW
- Thermal storage: 2000 m³
- Electricity spot prices: 2024 Nord Pool DK2
Grid tariffs are based on Cerius 2024 tariffs values for each of the four tariff groups:
| Group | Connection Voltage | Load Profile |
|---|---|---|
| B-low | 0.4 kV (Low voltage) | Low, predictable consumption; typical light industry |
| B-high | 0.4 kV or 10 kV (Low or medium voltage) | High or variable consumption; larger buildings, supermarkets, light industry |
| A-low | 10–20 kV (Medium voltage) | Moderate, possibly flexible consumption; medium-sized industry, institutions |
| A-high | 10–20 kV (Medium voltage) | High, steady consumption; large industry, data centers |
The tariffs change throughout the year and therefore an average tariff is used. See Grid Tariffs (Celcius) . The following heat demand profile is used:
Results
The simulations results are shown below in Figure 2 and Figure 3.
Key Findings
- Depending on the connection it is possible to reduce costs substantially. The difference between B-lav and A-high are approximately 0.8 mDKK/year or a relative cost reduction 15%.
- Deciding on a higher voltage / lower tariff connection type, requires additional complexity in form of a dedicated transformer.
- In summer months where the heat pump and storage capacity are relatively large compared to the demand, it is possible to shift production to avoid periods during the with high tariff costs. The difference in overall costs based connection types arise due to lower production flexibility in the winter months.
Conclusion
Grid-connection choice clearly affects OPEX. In this 2024 case, switching from the low-voltage B-lav tariff to the medium-voltage A-høj tariff lowers the annual grid bill by roughly 0.8 m DKK (about 15 %), mainly through lower electricity transport tariffs. The upgrade requires extra hardware and approvals, so each project should weigh those costs against the expected savings and revisit the calculation as tariffs and load profiles evolve.
Contact Clean Heat Partners at contact@cleanheatpartners.com.