Frequently asked questions about small-scale electricity generation
This page provides answers to some common questions and queries about small-scale electricity generation.
Frequently asked questions about small-scale electricity generation
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 optimally, 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.
Even if there is no surplus output, you need to make an agreement in accordance with the general terms of network service. Small-scale generators must have a buyer for the electricity they produce. 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?
You will not incur any charges for small-scale electricity generation. Your electricity retail company will pay you the agreed price for the surplus electricity you feed into the grid. This price is generally determined according to the situation in the electricity market. Caruna may collect a fee for this surplus electricity, but Caruna's fee will be significantly lower than the compensation you receive from the electricity supplier for the electricity you sell.
If a power plant has a nominal output of up to 100 kW, no electricity tax is levied for the generated electricity, and Caruna does not collect a fee for the surplus electricity fed into the grid. Most ordinary solar power plants used by households and agricultural sites have nominal outputs within this range.
If the output is more than 100 kW, we charge EUR 0.62/MWh (VAT 24%) for the surplus electricity fed into the grid. A megawatt-hour equals 1,000 kilowatt-hours of electrical energy.
How can I monitor how much electricity I generate?
You can use the energy monitor on Caruna+ to find out how much energy you have generated. Monitoring begins as soon as your power plant receives permission to connect to the network. The energy monitoring service shows how much electricity you have consumed, as well as the volume of surplus energy for which your electricity retailer will compensate you.
You can monitor your electricity generation using a fixed networked user interface provided by the equipment supplier or a computer or mobile application.
How is the generated electricity measured?
Caruna is responsible for measuring the volumes of consumed energy and energy fed into the grid. The same electricity meter is used for these purposes. We measure the volumes of electrical energy consumed and generated as hourly averages, and the system automatically calculates the net consumption and generation for the same hour.
It is not normally necessary to change the meter when you deploy generating equipment. We activate two-way metering when we grant permission to connect to the network, and we deliver the metering data 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 two-way metering?
Two-way metering covers all small-scale power generation facilities, including micro-generation plants with a total output of no more than 100 kW. When we grant you permission to deploy your small-scale generating equipment, the electrical energy you generate will be netted automatically.
The electricity I generate does not show up in monitoring. Why?
If you also consume electricity, figures are only shown for generation in the hours when the volume of electricity you generate exceeds the volume you consume. You need a valid electricity sales contract for the generation and consumption site in order to see the surplus generation figures. Caruna's electricity meter measures the electricity you consume and generate.
Measurement errors are extremely rare.
How big does my power plant need to be to make generation profitable?
A profitable generation plant should break even over the service life of the equipment. In the best cases, it may begin turning a profit in under 10 years.
The recommended size of the power 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 budget.
The factors specific to solar plants include your roof's surface area, direction and any shadows cast upon it. An expert supplier or electrical contractor can help you decide on the ideal size of your power plant.
What does 'nominal output' mean?
The nominal output of generating equipment is calculated according to its technical properties and indicates the maximum possible power output. The units of power may be kW (kilowatts) or kVA (kilovolt-amperes), which are equal to each other in this case. For example, the nominal output of a solar power plant is determined according to the details on the inverter and not necessarily on the basis of the imputed panel output directly.
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 (such as electricity storage). 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. You can verify the situation in your municipality from building control.
Caruna will grant a deployment permit for the power plant when your electrical contractor has provided us with details about the plant and you have made an agreement with an electricity retailer on the sale of surplus electricity. If we cannot grant a connection permit for the power plant straight away, we will contact you.
What are the requirements for disconnection switches?
It must be possible for a Caruna technician to disconnect your generation equipment 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 producer 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 electricity meter. It is also possible for each household to purchase its own power plant 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. If you live in a semi-detached house, it is advisable to make an agreement with your neighbour, and both households can purchase 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 all you are doing is adding extra solar panels and you are not changing the network system (the inverter), just let us know how much extra output you are installing by using the chat feature.
If you are installing new network systems or other forms of generation or replacing your existing generating equipment, your electrical contractor will submit a new notification to us.
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? For example, can I build a solar power array on the field next door and use the electricity in my current consumption point?
You can build a power plant on land other than the consumption facility connected to it (such as a house or industrial facility). The real estate may be owned by a different party, and the land 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 facility. Please note that the real estate where the power generating equipment is built cannot have a separate generation connection – the connection should be made to the consumption facility.
You do not need to ask Caruna for special permission in cases like this unless the power plant's output exceeds 2 MW.
Can I use my power plant to generate electricity if the power is cut off?
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 your own generation if there is a fault in the electricity network. Consult the equipment supplier or your electrical contractor to check the technical implementation. For further details, see our instructions.
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 facility. 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 accounting point and end the agreement for the generating facility. 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 facility agreement can end on the day when our technician removes the electricity meter. After that, we will delete the equipment details from the accounting point.