Geothermal energy baskets: costs, installation, manufacturers and experiences (2025)
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Stefano Fonseca ist Ingenieur für Energie und Umwelt mit über sechs Jahren Erfahrung in der technischen Gebäudeausrüstung (TGA). Er kombiniert technisches Fachwissen mit einer Leidenschaft für verständliche Kommunikation. Seit mehr als fünf Jahren schreibt er als freiberuflicher Redakteur über erneuerbare Energien und nachhaltiges Wohnen, insbesondere über Photovoltaik und Wärmepumpen.
Using geothermal energy in a confined space — is that even possible? Anyone who thinks of a heat pump with an area collector usually expects a great deal of effort and requires a lot of space. But there is a space-saving alternative: geothermal energy baskets. Here you can find out everything you need to know about this type of geothermal heat exchanger.
What are geothermal energy baskets?
Geothermal energy baskets are spiral geothermal heat exchangers made of plastic pipes, which are recessed vertically into pits. They consist of several turns of a brine circuit and use the surrounding soil mass to absorb near-surface geothermal energy. Thanks to their compact design, they save space and require significantly less space than classic area collectors.
How does a geothermal heat pump work with geothermal energy baskets?
A geothermal heat pump with geothermal heat baskets works in that the baskets absorb the heat from the ground via a brine circuit and transfer it to the heat pump evaporator. There, the refrigerant evaporates as a result of the absorbed heat. A compressor increases the pressure and temperature of the steam before it transfers its heat to the heating system in the condenser. The cooled brine flows back into the geothermal energy baskets, while an expansion valve lowers the refrigerant pressure. The cycle then starts all over again.
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Which requirements must be met?
For geothermal energy baskets to work efficiently, certain requirements must be met on the property and in the construction project:
- Sufficient space for the installation pits
- Digging depth of around 3 to 5 meters is possible
- Soil must be diggable and has good thermal conductivity (loamy, moist or mixed)
- No sealed surfaces above the installation location
- Adequate distance from buildings and property boundaries (depending on state law)
- Excavator or drill access required
- Check whether there is no permit or notification depending on the federal state (up to a depth of 10 meters usually without approval)
How does the installation work?
The installation of geothermal energy baskets requires careful planning and professional implementation. The entire process comprises several steps from preparation to commissioning:
- Calculate heat load: First, the heat requirement of the building is determined so that the required heat pump output and the number of geothermal energy baskets can be determined. A basket can produce around 1 to 1.5 kW of heating power.
- Analysis of soil conditions: The substrate is examined with regard to thermal conductivity and digging capacity.
- Positioning planning: The baskets are planned at a sufficient distance from each other (min. 2 m) and from buildings. The route of the brine pipes and the distributor are also determined.
- Excavation of pits: Cylindrical pits with a diameter of approx. 1.2 m and a depth of 3 to 5 m are excavated with a small excavator or mini excavator. The excavation must be stable and safe.
- Installing geothermal energy baskets: The pre-assembled spiral collectors are inserted vertically into the pits and aligned. If necessary, fixation is carried out to prevent slipping.
- Connection of brine pipes: The baskets are connected to a central brine distributor (collection shaft or technical room) via supply and return lines. The cables are laid and insulated to be frost-proof.
- Filling the pits: The pits are filled in layers with thermally conductive material (e.g. sand-clay mixture or original soil without stones). A good floor connection ensures heat absorption.
- Hydraulic balancing and tightness testing: After connection, the system is filled with brine, vented and tested for tightness. The hydraulic balance ensures a uniform flow through all baskets.
- Starting up the heat pump: After a successful test, the heat pump is started up, the control unit is adjusted and the system is checked for efficiency.
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How much do geothermal energy baskets cost?
Geothermal energy baskets cost an average of 20,000 to 35,000 euros, including heat pump, baskets, earthworks and installation in a single-family home. Depending on the manufacturer, a single geothermal basket costs between 400 and 800 euros. A typical single-family house with a heating load of 7 to 10 kW requires around 6 to 10 baskets, resulting in material costs of around 2,500 to 8,000 euros. In addition, earthwork costs 3,000 to 6,000 euros, depending on soil conditions.
How deep do geothermal energy baskets have to be installed?
Geothermal energy baskets must generally be installed 3 to 5 meters deep in vertical pits. The exact depth depends on the size of the basket, the heat requirement and the soil conditions.
How many baskets do you need?
As a rule, one geothermal basket is required for every 1 to 1.5 kW of heating output. A single-family house with a heating load of 7 to 10 kW therefore requires around 6 to 10 baskets. In an apartment building with a heating load of 20 to 30 kW, 15 to 30 baskets are required accordingly.
Are geothermal energy baskets subject to approval?
Geothermal energy baskets in Germany are generally without a permit unless they are installed in protected areas such as water protection areas. In most cases, a permit is only required for earthworks above 10 meters deep. Nevertheless, in most federal states, there is a notification obligation to the responsible water authority.
Can you install geothermal energy baskets yourself?
In principle, geothermal energy baskets can be installed by yourself if the necessary expertise and technology is available. Especially in the case of new buildings with their own excavator access, some of the costs can be saved by doing earthworks yourself. However, the connection to the heat pump and the filling of the brine circuit should be carried out by specialist companies.
Experiences with geothermal energy baskets: What do users say?
A user on the forum of Home technology dialog reports that the installation of geothermal energy baskets was easy to do on your own. The baskets were brought to a depth of about 5 meters, let into the pit with a rope and washed in during backfilling. Thanks to good preparation, the excavator was able to work without downtime. During operation, the brine intake temperatures were 5 °C even after winter, and there was no icing. The user sees advantages over the ring trench collector — in particular due to lower space requirements, more flexible construction and savings on personal input.
Can geothermal energy baskets be used in old buildings?
Geothermal energy baskets can also be used in old buildings if certain requirements are met. It is important that there is sufficient unsealed space for the baskets and that the heating load of the building is calculated precisely. In combination with a well-insulated building envelope and a low flow temperature, they also work efficiently in old buildings.
Which manufacturers offer geothermal energy baskets?
Several specialized manufacturers in Germany offer geothermal heat baskets as complete systems for brine-water heat pumps. The best-known providers include:
- BetaTherm: Develops compact spiral collectors for vertical installation with high efficiency
- GeoCollect: Offers modular collector systems that can also be used as a geothermal heat basket
- Weider heat pumps: Delivers geothermal heat baskets as part of coordinated heat pump solutions
- Noventec: Manufacturer of spiral geothermal baskets for tight spaces
- ZEROB: Specialized in maintenance-free plastic baskets with high heat absorption capacity
What are the advantages and disadvantages of geothermal energy baskets?
Geothermal heat baskets offer the advantage that they require significantly less space than traditional surface collectors and do not require expensive deep drilling. They can be installed quickly and comparatively easily, do not require approval and are suitable for smaller plots of land or renovations. Thanks to vertical installation, they also enable efficient use of near-surface geothermal energy.
Disadvantages arise in particular from the need to use an excavator, the limited heat removal per basket and the fact that no surfaces may be built over or sealed, as the soil must remain regenerable.
What alternatives to geothermal energy baskets are there?
Alternatives to geothermal heat baskets include geothermal probes, well systems (groundwater heat pumps) and air-water heat pumps. All systems use different heat sources: geothermal probes access deep layers of the earth, wells access groundwater and air-water heat pumps access the ambient air. The choice depends on plot size, land conditions, permits and budget.
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