Connecting generating equipment to the electricity network

Small-scale generating equipment can be connected to Caruna's electricity network via your existing accounting point or a new generation connection.

Small-scale electricity generation is usually connected to the customer's existing accounting point. The electrical energy you generate will be metered via the same electricity meter, and the volume of energy generated will be deducted from the volume consumed in the same period.  

You may consume less electrical energy than you generate in the same period, leading to surplus electricity. You can sell the surplus electricity to your chosen electricity retailer. You need an agreement on the sale of surplus electricity before we can grant you permission to connect your equipment, even if you have chosen equipment with optimal output.  

Equipment suppliers and electrical contractors can help you purchase the right kind of generating equipment and point out the requirements in areas such as disconnecting the generating equipment. The generating equipment can only be connected to the network when Caruna has issued a connection permit.

How to get a connection permit for your generating equipment

  1. Contact the supplier of the generating equipment.
  2. Contact our customer service team to check the connectivity of any electrical equipment rated at over 10 kW before you buy the equipment.
  3. The installation technician will send Caruna the details of the generating equipment.
  4. We will check the information in the notification and send you a Point of Delivery number so you can make an agreement on the surplus electricity.
  5. Contact your selected electricity supplier and make an agreement on the sale of surplus electricity. One way to find companies that buy electricity from small-scale generators is to use the Energy Authority's online service at sahkonhinta.fi
  6. The electricity retailer will notify us of the agreement, and then we will grant you permission to connect your generating equipment. You will also receive a confirmation of the electricity network agreement for generation.
  7. You can monitor the volume of surplus electricity you feed into the distribution network by opening 'Energy monitoring' on Caruna+ and entering your generation accounting point ID.

Solar and wind power plants with an output of up to 10 kW can always be connected to Caruna's network if you use fuses rated at 3 x 16 amperes or higher.

If the fuse size or network system at your accounting point is single-powered, the maximum connection power is 3.7 kW.

In addition to the output power, connectivity depends on the fuse size at the accounting point, as the peak power for the fuses limits the power output. The table below shows the maximum output power for the connecting party's fuse size.

Example: you are planning a solar power plant with an output of 6 kW, and the fuse size is 3 x 25 amperes – the generating equipment can be connected to Caruna's network.

Contact our customer service team to check the connectivity before you decide to buy power-generating equipment if the output is rated at over 10 kW.

Fuse size of the connectionMaximum output power (kW or kVA)
3x16 A11
3x25 A17
3x35 A24
3x50 A35
3x63 A44
3x80 A55
3x100 A69
3x125 A87
3x160A111
3x200 A139
3x250 A173

Generation connection

If you plan to sell the electrical energy you generate to the market or increase the fuse size at your accounting point due to generation, you may need a generation connection. A generation connection is an electricity connection primarily intended for generating electricity for the market. It may supply the electricity consumed by the generating equipment, as well as other consumption that is covered by the generated electricity.

Example: you plan to install some ground-mounted solar panels in your field, and there will not be any other consumption, or the amount of consumption will be low in relation to the volume of electrical energy generated by the solar power plant.

We will identify a suitable connecting point for a new generation connection in the existing network or build a connecting point up to the boundary of your plot of land. In such cases, the connection will take at least two months to deliver. You will be responsible for electrifying the plot from the agreed connecting point onwards (including a connection cable, distribution board and main fuse box, as for a new consumption connection).

There is no capacity reservation fee for generation connections with a power of less than 2 MW. In other words, the connection fee is based on the direct network construction costs. If the connection will be used for other consumption facilities in addition to the internal consumption of the generating equipment, the connection fee will be determined according to the consumption fuse size.

Power plants rated at up to 300 kW can be connected to Caruna's low-voltage network (voltage level: 0.4 kV), and we will install metering in the customer's meter-reading centre. Larger power plants are connected to the medium-voltage network (voltage level: 20 kV), and we will build a switching substation on the plot boundary, and the customer should connect a transformer using an in-feed. Caruna supplies metering and metering transformers to the metering cell in the switching substation.

It may take several months to implement a generation connection if network construction work is required. Contact our customer service team in advance via the chat feature to find out whether a generation connection can be made.

We need the following information to determine whether a generation connection can be made: 

  1. Form of generation, such as solar power, wind power, or biogas
  2. Planned generation output and potential expansion over a five-year period
  3. A map showing the location of the generating equipment on the real estate
  4. The connecting party's name and contact details
  5. Other technical documents necessary for determining connectivity, such as protection and safety documents

Professional electricity generation – Output exceeding 2 MVA

Large power plants generate electricity for the Finnish electricity market.  Examples of power plants include large wind and solar farms, generators and, in the future, electricity storage facilities.

Electricity network connections for generating equipment are investigated on a case-by-case basis. A representative of the customer should contact our experts in good time so that the preconditions for connecting the generating plant to the grid can be analysed. All power plants connecting to the grid must satisfy Fingrid's technical system requirements (VJV). Fingrid's SJV requirements apply to grid energy storage systems.

The network construction work may take from six months to several years. The duration depends on the scope of the project, the geographical location and the capacity of the electricity network.
If the desired connection capacity is not available, we can propose connecting the power plant at a lower capacity or study an alternative connecting point for the connection.

The pricing of connections is determined according to the costs of building the network and the capacity reservation fee.

PDF: Network service and connection fees for production in the distribution network 1.1.2022  >

Generating plants with a connection capacity of 2–5 MVA can connect to Caruna's medium-voltage distribution network. In such cases, we will typically build a customer switching substation up to the plot boundary, and the customer's connection line can connect to this using an in-feed. Caruna's switching substation will contain a remotely operated circuit-breaker cell equipped with energy metering and protection relays for the customer's connection.
In general, generating plants with a connection capacity of more than 5 MVA have a dedicated connection line to a dedicated 20 kV circuit-breaker cell at a Caruna substation or to the 110 kV high-voltage distribution network. 
We need at least the following information to determine whether a generating plant can be connected to the grid:

  • Planned method of generation
  • Planned generation output and the potential staggered growth over a five-year period
  • Whether a backed-up connection is required
  • Maps of the potential locations of the investment, showing the planned location of the customer's equipment on the real estate
  • The connecting party's name and contact details
  • Additional information about the investment timetable, town planning and permits related to the project

You can provide the aforementioned information to Caruna's contractor service team or key accounts team.

All generating equipment or electricity storage systems connected to the grid must fulfil Fingrid's applicable technical system requirements (VJV and SJV), depending on the type of power plant and electricity storage system (type A, B, C or D).

Grid Code Specifications for Power Generating Facilities VJV2018 (Fingrid)  >

Grid Code Specifications for Grid Energy Storage Systems SJV2019 (Fingrid)  >

Power plant's liability 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 grid. No electricity tax is levied on the electricity used for the power plant's internal consumption.