Renewable energy in the home is about covering part of your electricity and heating needs with energy from sources such as the sun, air, and ground—while reducing your dependence on fossil fuels. For many homeowners, the goal is lower energy bills, greater predictability, and better utilization of their own production. In practice, solar cells, heat pumps, and in some areas district heating are particularly relevant solutions. Here we review the options, economics, regulations, and key choices so that you can make an informed decision.
Definition: Renewable energy in the home is energy produced or collected from self-regenerating sources that can be used for electricity, heating, and hot water. In Denmark, the most relevant solutions are typically solar cells (electricity), solar heating (hot water/heating), heat pumps (heating), and district heating (heating).
Typical goals: For private individuals, it is often a matter of reducing costs, increasing self-consumption of solar power, and obtaining a more robust energy solution. For small businesses with residential-like consumption patterns, the same solutions may be relevant, but the tax treatment may be different if the system is operated commercially. When evaluating the solutions, it makes sense to start with two specific questions: What is your actual electricity and heating consumption throughout the day, and how much of that consumption can you shift to hours when you produce your own power – or when electricity is typically cheaper?
Solar cells (photovoltaic panels) convert sunlight directly into electricity and are the most common solution among Danish households. A typical family with an annual electricity consumption of around 5,000 kWh will often need a solar cell system of approx. 4–6 kW, which typically requires approx. 25–35 m² of roof space.
Before you decide, it is worth considering the practical factors that determine the yield: the slope and direction of the roof, shadows from trees/chimneys, and how much of your consumption occurs during the daytime. Solar cells may well be relevant even if you cannot use all the electricity immediately – but the solution often becomes more effective if you also plan for consumption management and possibly a battery.
When dimensioning a solar cell system, it is not just a matter of matching annual consumption. It is also about when you use the electricity. The more you can use directly, the more value you typically get out of the system under the applicable billing terms.
As a rule of thumb, it often gives a better result to choose a size that matches your realistic own consumption than to focus solely on maximum production. Oversizing can mean that a larger proportion of the production is sent to the grid, where the value depends on the current price and settlement.
Seasonal variation: Solar energy in Denmark varies throughout the year. Solar cells typically produce approx. 20–30% less in winter than in summer, while heating requirements are often highest in winter. Solar cells are therefore often combined with other heat sources and/or storage.
That is also why it can be advantageous to think holistically: if your home has high heating consumption during the winter, solar cells alone are rarely the answer. However, solar cells can be a powerful part of the solution when combined with a controllable heating solution and a consumption pattern that can be shifted. Here, it is important to clarify whether you can use solar power for, for example, hot water, charging, and other consumption that can be planned.
Solar heating systems utilize the sun's heat directly and can be used for hot water and, in some solutions, also for space heating via a hot water tank and the home's heating system.
Solar heating makes the most sense when there is a stable demand for hot water and when the system can be integrated sensibly with the existing hot water tank and heating circuit. When evaluating the solution, you should therefore clarify how your current system is structured and whether there is room for the necessary components.
Regardless of the solution, you should ensure that the dimensions match your needs and that there is a clear plan for how it will interact with your other heat sources. This makes it easier to assess whether the investment fits your time frame and the technical framework of your home.
Heat pumps utilize heat from the air or ground and deliver heat to the home with high efficiency. Efficiency is often described using COP (Coefficient of Performance). A COP of around 4 means that the heat pump can deliver approx. 4 kWh of heat for every 1 kWh of electricity it uses.
In practice, the result is closely linked to the level of insulation in your home and the temperatures of your heating system. If your home requires a high flow temperature, or if heat loss is significant, this can affect operation and economy. It is therefore a good idea to clarify whether there are any obvious energy improvements that should be prioritized before or at the same time as the heat pump.
The choice of heat pump depends mainly on the heating distribution in your home (radiators/underfloor heating), space constraints, and whether you want to avoid digging or drilling work. Here are the typical options and their requirements.
Before proceeding, it is advisable to check whether there is sufficient space and access for the installation, and whether there are any special local requirements, such as noise regulations for the outdoor unit in air-based solutions.
Savings (example): In a standard 130 m² detached house, switching from natural gas to a heat pump can result in savings of around DKK 11,000 per year on heating bills (according to the Danish Energy Agency). Over a typical lifetime of approx. 20–25 years, this can result in significant total savings, but the result depends on energy prices and the condition of the home.
Prerequisite: Good insulation is important for optimal heat pump performance. In older, poorly insulated homes, the economic benefits may be less if energy efficiency improvements are not made at the same time.
In everyday life, good operation is all about correct adjustment and realistic expectations: A heat pump typically performs best when it is allowed to run steadily and when the heating system is adjusted so that the home is heated evenly. Therefore, you should ensure that the supplier reviews the settings and operation with you and that there is a plan for annual maintenance to maintain performance.
Around 60% of the population has access to district heating. District heating distributes hot water via insulated pipes to the home's radiators/underfloor heating and domestic hot water.
If district heating is an option, it is often a solution that requires relatively little space in the home and limited maintenance. On the other hand, you should consider the commitments and conditions involved, because in practice you are tying yourself to a supplier and a local pricing and delivery regime.
A practical next step is to clarify the specific connection terms and deadlines so that you can compare district heating with alternatives such as heat pumps on a calm, informed basis.
The rules for settling solar cell surpluses were changed from January 2024, so that private solar cell owners are settled via Group 3 (instant settlement). This means that the electricity must either be used immediately in the home or sold to the grid immediately. Many therefore choose to use batteries to store the day's surplus production for later – typically for evening hours when consumption is higher and the price of electricity is often higher.
A battery is particularly valuable when there is a clear imbalance between production and consumption: high production in the middle of the day and high consumption in the evening. To achieve the practical effect, you typically also need to consider which consumption can be shifted (e.g., hot water, laundry, and charging) and how the control system should prioritize between direct consumption, battery charging, and possibly selling to the grid.
Effect on self-sufficiency: With a battery pack of approx. 5–10 kWh, the degree of self-sufficiency can be significantly increased, e.g. from around 50% to around 80% in a combination solution.
Regulations and permits can be crucial to your schedule and budget. It is therefore a good idea to clarify the requirements early on to avoid projects being delayed by missing notifications or necessary approvals.
If you live in an area with special local plans or in a type of housing with common rules, it may be relevant to clarify the requirements before ordering equipment. This ensures a more secure process from quotation to final installation.
Schematic arrangement: Private individuals may sell electricity for up to DKK 7,000 per year without paying tax. If sales exceed DKK 7,000, 60% tax is payable on the amount above DKK 7,000. Own consumption of electricity from solar cells is tax-free.
In practice, this means that planning for high self-consumption can be important. It is also a good idea to make sure you know which scheme you are covered by and how your electricity production and billing are recorded, so that you avoid errors in your statements.
Subsidies and tax credits can improve your finances, but they typically come with conditions and documentation requirements. Make sure you clarify what applies to your specific home and installation, and save relevant documentation from your supplier and installer.
A practical tip is to factor deductions and subsidies into your decision early on, so that you can compare solutions on a consistent basis and avoid basing your finances on assumptions that do not apply to your situation.
The combination of solar cells and heat pumps is widespread because solar cells can supply part of the electricity consumption for the heat pump. A rule of thumb for dimensioning is approx. 1 kW of solar cells per 1,000 kWh of annual energy consumption. In a typical combination, a 6 kW solar cell system can produce approx. 5,500–6,000 kWh/year, while the heat pump's electricity consumption can be around 3,000–6,500 kWh/year.
To get the full effect, you should look at the interaction between production and consumption: Solar cells produce most in the middle of the day, while heating requirements and other electricity consumption often occur in the morning and evening. Therefore, it may be relevant to plan how the system should prioritize when electricity is produced: Should it be used directly, should some be used for hot water, or should it be stored for later?
Control: Intelligent energy management can optimize operations by using electricity when solar cells are producing or when electricity prices are low, and storing energy in the battery for expensive hours.
First step: Start with an energy assessment, reviewing the roof, shade, orientation, insulation, and consumption patterns of the home. To minimize risks, it is recommended to use a qualified renewable energy installer who can correctly size the system and ensure a safe connection.
It makes the decision easier if you have gathered the information that the installer typically needs in advance: your latest electricity and heating consumption statements, information about your current heat source, and clarification of whether there are any plans for changes that will affect consumption. This will enable you to obtain a more accurate proposal for sizing and a more realistic assessment of the financial and operational aspects.
Finally, you should ensure that there is a clear plan for commissioning and follow-up. This can be as simple as reviewing how to read production and consumption, and which settings are important in everyday use. This makes it easier to detect deviations early on and get the effect you have invested in.
Do you have questions or need advice? Our experts are ready to help you.
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