Connecting generating equipment to the electricity network
Interest in on-site electricity generation has increased in recent years. Up to 20,000 power plants have already been connected to Caruna's distribution network, most of which are solar power plants on or near houses. Thanks to the energy transition, almost all new power plants use renewable energy sources.
Small-scale electricity production is usually connected to the electricity connection of the customer's existing point of delivery. The equipment supplier scales, acquires and installs the generating equipment. The equipment may not be deployed until Caruna has granted a connection permit for it.
The electrical energy you generate will be metered via the same electric meter as the consumption of the point of delivery, and the volume of energy generated will be deducted from the volume consumed in the same period.
Even if you don't consume all the generated electricity yourself, you will benefit from the power plant. You can sell the energy generated from your production to the electricity supplier of your choice after netting. For this, you will need an agreement on the sale of surplus generation, and it is also a requirement for receiving a connection permit. An agreement is required even if the equipment is sized to maximise the use of the electrical energy generated for your property's electricity consumption.
For generation plants directly connected to an inverter (solar panels, small wind turbines, batteries, etc.), the maximum possible output power is determined by the nominal output of the inverter (kW/kVA) or the combined nominal output of several inverters (kW/kVA).
Connecting generating equipment to an existing connection step by step
Contact the equipment supplier first and find out the size of generating equipment that is suitable for your needs
The equipment supplier will scale and design the optimal size of generating equipment that is most suitable for your needs.
If the size of the generating equipment exceeds 10 kW, check its connectivity with our customer service chat before you buy the equipment
Solar and wind power plants with an output of up to 10 kW can be connected to Caruna's network if you use fuses rated at 3x16A or higher. If the fuse size or network system at your point of delivery is 1-phase, the maximum equipment power is 3.7 kW.
For equipment above 10 kW, the connectivity assessment is influenced not only by the strength of the electricity network, but also by the fuse size of the point of delivery and the connection rights of the connection. The fuse size of the point of delivery and the maximum permitted fuse size of the connection according to the connection right limit the amount of output power. The fuse size of the point of delivery must be increased if the capacity of the generating equipment exceeds the peak power corresponding to the fuse size of the point of delivery. In addition, if the capacity of the equipment exceeds the maximum output power in accordance with the connection rights, a generation connection contract must be concluded before the equipment is deployed, in addition to the fuse enlargement.
Checking connectivity will be faster if you have determined the size of the generating equipment beforehand.
The installation technician sends Caruna the details of the equipment
The equipment supplier ensures that the technical specifications of generating equipment required by Caruna are fulfilled.
We check the details of the generating equipment from the general request form. Based on this information, our customer service creates a dedicated point of delivery for generation alongside your consumption point of delivery. We then activate bidirectional measurement for the electric meter.
You will receive a generation point of delivery ID from us for concluding a purchase agreement on surplus electricity
Contact your selected electricity supplier and make an agreement on the sale of surplus electricity. The start date of the agreement should be the date of installation of the equipment or a few days earlier. This will give you the best possibility of obtaining a connection permit so that you can start using the equipment from the day of installation.
One way to find companies that buy electricity from small-scale generators is to use the Energy Authority's online service at sahkonhinta.fi.
You receive a connection permit for the generating equipment by text message
You will receive a connection permit as soon as the electricity supplier of your choice has notified us of the surplus electricity purchase agreement.
Do not deploy your generating equipment before you have received our connection permit! Contact your electricity supplier well in advance to get a connection permit for the equipment at the desired time.
Monitor the amount of surplus electricity you have transmitted to the distribution network from electricity monitoring
The Caruna+ electricity monitoring allows you to check the data stored by your electric meter, such as the total distribution, billable consumption, surplus production, production eligible for reimbursement, and production to be sold.
Caruna's records will not include anything that happens in your property before the electric meter. These include the amount of electricity produced by solar panels and how much of the electricity you produced was consumed in your property.
Check the table for the maximum output power corresponding to the fuse size of the point of delivery and the connection right of the connection.
If you do not know the connection right of your connection, you can check it on Caruna+. If the details about the connection contract are now shown in our service, it is possible that the owner of the electricity connection has not been updated to Caruna, for example in connection with a property transaction. If the connection should be in your ownership, submit a change of ownership form to bring the electricity connection into your name.
Whatever the fuse size of the connection, the connectivity of all generating equipment over 10 kW must be checked with Caruna before purchasing the equipment.
|Connection fuze size||Maximum production power (kW or kVA)|
Must all generating equipment be notified to Caruna?
Information on all equipment connected to Caruna's network that can supply electricity to the electricity network must be provided on the general request form. In addition to solar panels, these include bidirectional car charging points, batteries and small-scale wind power stations. Your electricity contractor fills in the general request form on Caruna's website.
Why do I need to make an agreement on the sale of electricity when I consume all the electricity myself?
Even if your generating equipment is scaled to utilise most of the production in your own consumption, the electrical energy you generate may exceed your own consumption momentarily. In this case, the surplus electricity is transferred to Caruna's network. This is common for solar plants, which have the highest output in the summer when consumption is usually lower than in the seasons in which buildings are heated.
Small-scale generators must have a buyer for the electricity they produce. Even if there is no surplus output, you need to make an agreement in accordance with the general terms of network service. This also applies in the event that an electricity supplier's agreement ends due to a move or change of supplier. In these cases, a new agreement must be made with the selected electricity supplier for the generation and consumption point.
How much will be charged for the electricity I generate?
If a power plant has a nominal output of up to 100 kW, no electricity tax is paid on the generated electricity, and Caruna does not collect a fee for the surplus electricity fed into the network. Most ordinary solar power plants used by households and agricultural sites have nominal outputs within this range.
If the output power exceeds 100 kW, we charge for the surplus electricity fed into the network in accordance with the electricity generation network service and connection fee price list.
How can I monitor how much electricity I generate?
You can monitor your electricity consumption and the volume of surplus electricity generated in Caruna+ once you have received a connection permit for the generating equipment.
You can monitor the total amount of electricity your solar panels generate by checking the screen on the inverter connected to your solar panels or by accessing your equipment supplier's service.
How is the generated electricity measured?
Caruna is responsible for measuring the volumes of consumed energy and energy fed into the network. The same electric meter is used for these purposes. We measure consumed and generated electrical energy as an hourly average. Netting of generation and consumption is carried out in the datahub service maintained by Fingrid.
Almost all Caruna electric meters can be remotely activated as bidirectional without changing the meter. Activation takes place when processing the production general request form from your electricity contractor. We will contact you if the meter must be changed. We deliver the metering data through datahub to your electricity supplier, which buys the surplus energy fed into Caruna's network.
How can I check that my energy generation is covered by netting?
All equipment under 100 kW is automatically covered by netting when a connection permit has been granted.
How big does my generation plant need to be to make generation profitable?
The recommended size of the generation plant depends on several factors, such as the volume of electricity you currently consume, your consumption profit (including how you heat your property and the effect of charging electric vehicles), location and your budget.
The factors specific to solar plants include your roof's surface area, direction and any shadows cast upon it. An expert supplier or electricity contractor can help you decide on the ideal size of your power plant.
What determines the peak power of generating equipment?
The peak power of generating equipment is calculated according to its technical properties. For example, the nominal output power of a solar plant is determined based on the inverter data. The units of power may be kW (kilowatts) or kVA (kilovolt-amperes), which are equal to each other in this case.
How much compensation will I receive for the electricity I generate, and is it worth selling the generated electricity?
The amount of compensation depends on your agreement and the services provided by your electricity supplier. You can find out about compensation by requesting quotes from different electricity suppliers. One way to compare electricity suppliers is to use the Energy Authority's sahkonhinta.fi service.
Do I need any permits to install a power plant?
Some municipalities may require an action permit for work such as installing solar panels. Verify the situation in your municipality from building control.
Caruna will grant a deployment permit for the generating equipment when your electricity contractor has provided us with details about the equipment on the general request form and you have made an agreement with your electricity supplier on the sale of surplus electricity. If we cannot grant a connection permit for the generating equipment straight away, we will contact you.
What are the requirements for disconnection switches?
It must be possible for a Caruna technician to disconnect your generating equipment from the electricity network if necessary, for example, to repair a fault. For this purpose, there must be a disconnection switch installed in an accessible location, such as the exterior wall of the building. If the disconnection switch is in a locked area, such as an engineering and utility services room, you must arrange access according to our guidelines.
Can I become a small-scale generator if I live in a housing company or semi-detached house?
Housing companies usually purchase shared generating equipment and connect it to the real estate electric meter. A household-specific power plant is also possible if, for example, solar panels can be installed on the roof of one of the buildings and the housing company grants permission for the installation. In semi-detached houses, you should also agree with your neighbour. Both households can acquire their own power plants.
When you choose the scale of a power plant for a housing company or semi-detached house, bear in mind that the total output of the power plants operating in different places is calculated – including different forms of power generation, such as solar power and wind power – if they are linked to the same physical electricity connection. Contact our customer service team via chat to discuss connectivity.
I am expanding my power plant. How should I report this?
If the power or technical implementation of the generating plant changes, your electricity contractor must notify us of the changes using the general request form. We will check the connectivity of the equipment based on the changed output power.
Example: the existing, low-power 3 kW inverter is removed and replaced by a higher-power 10 kW inverter. We will check the connectivity according to the technical details of the new inverter.
Example: a 15 kW solar power plant will be installed in addition to a small, 3 kW wind power plant. We will check the connectivity for the total output of 18 kW.
If the new output power is greater than 10 kW, contact us to check the connectivity of the equipment in advance.
Can I install a power plant outside my real estate and use the electricity in my current point of delivery?
You can build a power plant on property other than the consumption point of delivery connected to it (such as a house or industrial facility). The real estate may be owned by a different party, and the property does not need to be geographically adjacent.
The landowner must grant permission to build the power plant, and you must get the necessary permits from the authorities and municipality. You are responsible for building a connection line between the generating plant and the switchboard at the consumption point of delivery.
Can I use my power plant to generate electricity if the power is cut off?
No. For electrical safety reasons, power plants switch off automatically at the beginning of a power cut and back on after the power cut.
If your power plant is connected to a battery, you can use the electricity stored in the battery if there is a fault in the electricity network. Consult the equipment supplier or your electricity contractor to check the technical implementation.
Can electricity generation be transferred to a new owner in the event of a move?
A small-scale power plant is usually a profitable investment that raises the value of real estate. When you sell your real estate, it is a good idea to tell potential buyers about the power plant – for example, solar panels on the roof.
When you have sold the property, the new owner should transfer the electricity connection into their name and make an agreement with their chosen electricity supplier for the consumption and generation point of delivery. This will enable the buyer to take advantage of the electrical energy they generate.
I plan to stop using my generating equipment. How should I report this?
Use the customer service chat feature to let us know you are planning to stop generating. We will delete the equipment details from the point of delivery and end the agreement for the generating point of delivery. We will also notify your electricity supplier.
If the generating equipment is removed when the building is demolished, the change can be made when the electricity connection goes into maintenance or is terminated. The generating point of delivery agreement can end on the day when our technician removes the electricity meter. After that, we will delete the equipment details from the point of delivery.
The capacity of my generating equipment exceeds the maximum capacity of my connection rights. However, can the equipment be connected to the network?
If the maximum power fed to the network by the generating equipment is limited by a separate smart control system, connectivity can be considered on the basis of the limited output power. This can make sense, for example, for sites with more than one form of production. Without limitation, the output power must not exceed the power of the connection's main fuse size.
Are power plants liable for electricity tax?
Electricity generators fall into three categories in terms of their electricity tax liability:
Output power up to 100 kVA
Small-scale generators are not liable for electricity tax. Small-scale generators do not need to register as liable for tax, nor do they need to file tax returns on their electricity generation.
Output power over 100 kVA, up to 800,000 kWh of electrical energy generated per year
The electricity generator must register with the Tax Administration as an entity liable for electricity tax. The electricity generator must file an annual tax return so that the annual generation limit can be supervised.
Output power over 100 kVA, more than 800,000 kWh of electrical energy generated per year
The electricity generator must register with the Tax Administration as an entity liable for electricity tax. The electricity generator must file a monthly tax return, irrespective of whether the power plant feeds electrical energy into the network. No electricity tax is levied on the electricity used for the power plant's internal consumption.