Renewable Electricity for Heat Pumps
Renewable electricity is electrical energy generated from hydropower, wind power, photovoltaics, biomass, or geothermal energy. A heat pump uses this electricity as its power source to raise ambient heat from the air, water, or ground to a usable temperature level.
The principle is straightforward: only when the electricity used is itself renewable does the inherently renewable heat available in the environment translate into a climate-friendly heating process in practice. The share of renewable energy in the electricity mix therefore directly determines how climate-friendly a heat pump is during actual operation, regardless of its technical efficiency.
What is Renewable Electricity in Heat Pump Environment?
Renewable electricity refers to electrical energy generated from sources that are naturally replenished, including hydropower, wind power, solar energy, biomass, and geothermal energy. It stands in contrast to electricity generated from fossil fuels such as coal, natural gas, and oil, as well as nuclear power.
In the context of heat pumps, renewable electricity is the energy source that powers the compressor, enabling ambient heat to be transferred to the building’s heating system.
The renewable share of the electricity consumed can be obtained in two ways: through electricity drawn from the public grid, which contains a corresponding share of renewable energy, or through on-site generation, for example from a photovoltaic system installed on the building.
What is the Purpose Renewable Electricity in Heat Pump Environment?
The purpose of using renewable electricity to operate a heat pump is to realize the system’s full climate benefit. A heat pump extracts free, renewable thermal energy from the environment, and this process itself produces no direct emissions. However, the compressor that drives the process requires electricity, and the source of that electricity determines the actual carbon footprint of the entire heating system.
When the electricity comes from fossil-fuel power plants, the climate benefit of the heat pump is significantly reduced, even though its technical efficiency remains unchanged. When the electricity comes from renewable sources, the heat pump becomes an almost entirely emissions-free heating system.
Renewable electricity is therefore essential if the physical advantage of a heat pump—producing three to five units of heat from one unit of electricity—is to deliver its full climate benefit.
Why Renewable Electricity Is Necessary
The importance of renewable electricity is driven by three developments that have a direct impact on heat-pump operation.
Regulatory Framework
The EU Renewable Energy Directive, RED III—Directive (EU) 2023/2413—sets a binding target for renewable energy to account for at least 42.5% of total EU energy consumption by 2030.
Heat pumps are also subject to a specific requirement. Under Annex VII of the Directive, heat supplied by a heat pump counts as renewable energy only when its seasonal performance factor, or SPF, exceeds the minimum threshold of 2.5. This threshold directly links recognition as renewable energy to both the efficiency of the heat-pump system and the efficiency of the upstream electricity system.
Different Starting Positions in Each Country
The share of renewable energy in grid electricity varies considerably across Austria, Germany, and Switzerland. As a result, the actual carbon footprint of a heat pump differs depending on where it is installed.
| Country | Share of Renewable Electricity | Dominant Source | National Target | Source |
|---|---|---|---|---|
| Austria | Approx. 87.5% in 2024 | Hydropower, approximately 60% | 100% on a net annual basis by 2030 under the EAG | E-Control / energie.gv.at |
| Germany | 55.1% of gross electricity consumption in 2025 | Wind power | At least 80% by 2030 under the EEG | German Environment Agency |
| Switzerland | Hydropower alone accounted for approximately 57% in 2024; more than 75% was renewable overall | Hydropower | 70–80% by 2035 | Swiss Federal Office of Energy, SFOE |
Austria is therefore well above the EU average of approximately 48% renewable electricity, according to analyses based on Eurostat and Ember data. This gives heat pumps installed in Austria an automatic location-based advantage. In countries with a lower renewable share, actively choosing the source of the electricity becomes considerably more important.
Electrification of the Heating Sector
As heat pumps increasingly electrify the heating sector, the source of the electricity becomes more important with every additional system installed. Without a growing share of renewable electricity, the electrification of heating would add to the carbon burden of the electricity sector rather than reduce it.
Key Features of Renewable Electricity
- Grid-supplied green electricity: Electricity obtained from the public grid with a certified renewable-energy share
- On-site PV generation: Solar electricity generated at the property and used directly by the heat pump
- Guarantee of Origin: A certification system that verifies renewable electricity and makes its renewable attributes tradable
- Smart-grid integration, or SG-Ready: An interface that enables a heat pump to respond to electricity availability and price signals
- Dynamic electricity tariffs: Pricing models that align electricity consumption with the availability of renewable energy
- SPF threshold under the RED: The minimum regulatory efficiency requirement that must be met for heat to qualify as renewable energy
Detailed Explanation of the Features
Grid-Supplied Green Electricity
Grid-supplied green electricity is electricity purchased from the public grid through a certified renewable-electricity tariff. Its purpose is to enable renewable heat-pump operation without requiring an on-site generation system.
Its main advantage is immediate availability. Changing electricity tariffs does not require any construction work or capital investment and can take effect from the next billing period.
Practical example: A household without a photovoltaic system switches to a certified green-electricity tariff when installing a heat pump. This allows the system to operate with demonstrably renewable electricity from the outset.
On-Site PV Generation
On-site PV generation refers to electricity produced directly at the building by a photovoltaic system and used to operate the heat pump. Its purpose is to reduce the amount of electricity drawn from the grid and increase independence from fluctuations in electricity prices.
The advantage is that self-generated electricity does not incur grid charges and avoids transmission losses, making it particularly attractive from an economic perspective.
Practical example: A heat pump with an SG-Ready interface prioritizes surplus PV electricity around midday to charge a thermal buffer tank. The stored heat is then available for use during the evening.
Guarantee of Origin
A Guarantee of Origin is an electronic certificate confirming that a specific quantity of electricity was generated by a renewable-energy installation. It also prevents the renewable attribute of that electricity from being sold or claimed more than once.
Its purpose is to provide transparency. It prevents electricity suppliers from marketing electricity as “green” without cancelling the corresponding certificate.
The main benefits are regulatory assurance and greater customer confidence.
Practical example: The national Guarantee of Origin registers are administered by E-Control in Austria, the German Environment Agency through the HKNR in Germany, and the Swiss Federal Office of Energy in Switzerland.
Smart-Grid Integration, or SG-Ready
SG-Ready is a standardized interface that allows a heat pump to respond to grid signals, surplus PV generation, or electricity-price signals.
Its purpose is to shift electricity consumption to periods when renewable electricity is abundant or prices are low. The primary advantage is a noticeably higher rate of self-consumption. According to market data, the self-consumption rate without intelligent control is typically around 25–35%, while SG-Ready control can increase it considerably.
Practical example: An energy-management system detects surplus PV generation and automatically activates an SG-Ready operating mode that increases buffer-tank charging. Solar electricity generated around midday is therefore stored as heat and used in the evening.
Dynamic Electricity Tariffs
Dynamic electricity tariffs are pricing models in which the electricity price changes hourly in line with wholesale-market prices, such as EPEX Spot prices.
Their purpose is to create a financial incentive to shift electricity consumption to periods of high wind or solar generation, when prices are generally lower. The advantage is a direct reduction in costs while indirectly encouraging the use of surplus renewable electricity.
Practical example: A heat pump preferentially charges its buffer tank during a windy night when wholesale electricity prices are low, rather than operating during a daytime peak-demand period.
SPF Threshold under the RED
The SPF threshold—Seasonal Performance Factor, also known as the Jahresarbeitszahl or JAZ in German-speaking countries—is the minimum regulatory requirement set out in Annex VII of the RED.
Under this requirement, a heat pump must achieve an SPF of at least 2.5 for its heat output to qualify as renewable energy.
The purpose of this threshold is quality assurance. Only systems that deliver significantly more heat than the amount of electricity they consume qualify as genuinely renewable. The threshold also provides a reliable basis for national incentive programs and energy statistics.
Practical example: An air-source heat pump with an SPF of 3.5 clearly exceeds the required threshold and is recognized as a renewable heat source in the national energy balance.
Types and Models
Grid-Supplied Green Electricity
Electricity is obtained through a certified renewable-electricity tariff without the need for an on-site generation system.
On-Site PV Generation without Storage
Solar electricity is used directly as soon as it is generated.
On-Site PV Generation with Battery Storage
Surplus PV electricity is stored and made available during periods with little or no sunlight.
Renewable Energy Communities
In Austria, these models are regulated under the Renewable Energy Expansion Act, or EAG. They allow multiple households to jointly generate renewable electricity and share it among themselves.
Hybrid Model
A hybrid model combines on-site PV generation, grid electricity, a dynamic tariff, and SG-Ready control to provide maximum flexibility.
Each model differs in terms of the required investment, degree of energy independence, and speed of implementation. The most suitable choice depends on the type of building, the available space, and the applicable regulatory framework.
Use Cases
New Building with Photovoltaics
The PV system and heat pump are planned together from the outset. The design includes an SG-Ready interface and an appropriately sized thermal buffer tank.
Existing Building without Photovoltaics
Switching to a certified green-electricity tariff enables renewable heat-pump operation without requiring construction work. This is a practical first step when replacing the heating system in an existing building.
Apartment Building or Commercial Property
Joining an energy community allows several units to generate and use renewable electricity collectively, even when individual apartments do not have access to their own roof space.
Retrofitting as Part of a Renovation
Existing heat pumps without smart-grid functionality can be upgraded during modernization by adding an SG-Ready interface and an energy-management system.
Benefits
- A reduced operational carbon footprint because the electricity consumed produces no emissions, or only minimal associated emissions
- Compliance with regulatory requirements, particularly the SPF threshold under Annex VII of the RED
- Greater cost stability because on-site PV consumption and green-electricity tariffs reduce exposure to fluctuations in fossil-fuel prices
- A contribution to grid stability through load shifting with SG-Ready control and dynamic tariffs
- Greater future readiness in view of rising carbon prices for fossil fuels and increasingly stringent requirements for controllable electrical loads
Selection Criteria
Regional Renewable Share of Grid Electricity
This determines how much additional climate benefit can be achieved by actively selecting a particular electricity source.
Suitability for Photovoltaics
Relevant factors include available roof space, roof orientation, shading, and local incentive programs.
SG-Ready Compatibility
The selected heat-pump model should be checked for compatibility with SG-Ready control systems.
Availability of Dynamic Tariffs
The availability of dynamic electricity tariffs varies between grid areas and electricity suppliers.
Grid-Connection Requirements
In Germany, for example, new electrical consumption devices with a capacity above 4.2 kW have been subject to controllability requirements under Section 14a of the German Energy Industry Act, or EnWG, since January 1, 2024.
Eligibility Requirements for National Incentive Programs
Some national incentive programs make funding conditional on SG-Ready capability, Guarantees of Origin, or other technical and administrative requirements.
Comparisons
Green Electricity vs. Grey Electricity
Green electricity is electricity from renewable sources that is certified through Guarantees of Origin. Grey electricity is electricity without this certification and, depending on the grid mix, may include a higher proportion of fossil-fuel and nuclear generation.
The distinction directly affects the carbon footprint of heat-pump operation, even though both types of electricity are physically supplied through the same grid.
PV Self-Consumption vs. Grid-Only Supply
PV self-consumption reduces operating costs and increases energy independence, but it requires an initial investment.
Grid-only supply through a green-electricity tariff is immediately available and does not require an investment in generation equipment. However, it does not provide the same level of independence from changes in market prices.
Fixed vs. Dynamic Electricity Tariffs
A fixed tariff provides greater price certainty but does not take advantage of low-cost periods when surplus renewable electricity is available.
A dynamic tariff follows wholesale electricity prices and rewards intelligent control that shifts consumption to more favorable periods, provided that the heat pump has an appropriate control interface.
Country Comparison
As shown in Section 3, Austria, Germany, and Switzerland differ considerably in the renewable share of their electricity mixes.
These differences complicate direct cross-border carbon comparisons between otherwise identical heat-pump installations and should be taken into account in every carbon-footprint assessment.
In practical applications, the iDM Navigator energy-management solution connects these different layers. It coordinates PV generation, SG-Ready-compatible iDM heat pumps, and buffer-tank charging to maximize the share of self-generated electricity or renewable grid electricity used during operation. In this way, it translates the principles described in this article into a concrete, integrated system solution.
