Photovoltaics are gaining popularity across the country. More and more home and business owners are choosing to install solar panels to reduce their energy bills and become independent of rising electricity prices. However, before the installation starts working, the investor must take into account the specific technical and legal requirements that govern its operation. What is the permissible power of a photovoltaic installation?
The permissible power of a photovoltaic system depends on a number of factors – including the type of installation, the method of connection to the grid and the status of the prosumer. In this article, we present the current regulations in force between 2024 and 2025, discuss the differences between a micro and a small installation, and explain how to choose the right system power for the technical possibilities of the building. We also give advice on how to go through the formal procedures and what documents to prepare before starting the installation.
Permissible capacity of photovoltaic installations – definitions and legal limits
A photovoltaic micro-installation is a source of renewable energy with a capacity not exceeding 50 kW. Individuals who install such installations on residential buildings or plots of land act as prosumers. They are entitled to feed surplus energy back into the electricity grid and benefit from net-billing or other forms of support. The maximum capacity of a prosumer installation is just 50 kW – exceeding this threshold results in a reclassification of the system.
Installations with a capacity between 50 and 1,000 kW are considered so-called small installations. Such systems can only be carried out by commercial operators who have the relevant authorisations – including a licence and registration in the register of energy producers. In practice, this means that a private individual cannot build an installation of more than 50 kW without becoming an energy entrepreneur.
It is also worth bearing in mind the construction issues. From 1 October 2023, regulations come into force that remove the requirement for a building permit for photovoltaic installations up to 150 kW (previously the limit was 50 kW). For installations up to 50 kW, a simple notification of construction work – including a site plan – submitted a minimum of 30 days before the start of installation is still sufficient. In addition, for installations above 6.5 kW, it is necessary to obtain the opinion of a fire protection expert and to prepare the required technical documentation.
Permissible power of photovoltaic installation vs. single-phase and three-phase installation
Technical regulations and operator guidelines clearly define the maximum power of a photovoltaic installation depending on the type of connection. According to the current regulations, generating sources with a power of more than 3.68 kW must be connected three-phase. This means that, in the case of a single-phase installation, the permissible power of a photovoltaic installation cannot exceed the aforementioned value. Exceeding this limit results in the automatic rejection of the application by the distribution system operator.
Owners of properties with a three-phase installation are not subject to such restrictive limitations at the single-phase level. In their case, the load can be safely distributed over three phases, which makes it possible to install a higher output – for example, up to around 11 kW using a three-phase inverter or several single-phase inverters.
Connection power vs. permissible power of a photovoltaic installation
However, it is worth remembering that the general limit for prosumers still applies – the total power of the installation cannot exceed 50 kW. In practice, many investors choose to slightly oversize their panels in relation to the inverter power – usually by around 20 per cent. This increases energy production in less favourable conditions, e.g. mornings, evenings or slightly cloudy periods, without the risk of overloading the inverter.
The permitted power of the photovoltaic installation must also be within the connection power specified for the building. Each energy consumer has an individually allocated value for this power – usually 6 kW or 10 kW for detached houses. If the planned installation is to generate more energy than the current connection capacity allows, it is necessary to submit an application for an increase. The grid operator considers this based on the technical capacity of the area. This procedure can take several weeks, so it is advisable to consider it at an early stage of planning your investment.
Micro installation, prosumer and support schemes
Owners of photovoltaic micro-installations up to 50 kW can benefit from special billing rules for surplus energy fed into the grid. There are currently two main models: net-metering (a system of discounts) and net-billing. In the former, each kilowatt-hour fed into the grid reduces the energy bill at a ratio of 0.8:1 or 0.7:1 – depending on the size of the installation. In the net-billing model, the prosumer sells the surplus at the market price and the amount received goes into his prosumer account.
The November 2024 amendment to the Act introduced significant changes for owners of installations commissioned before 1 July 2024. They can benefit from monthly billing (RCEm) and also voluntarily switch to hourly billing (RCE). For installations commissioned after 1 July 2024, only hourly billing applies. At the same time, the legislator has increased the value of the prosumer deposit by 23%, which translates into greater benefits for each kilowatt hour given to the grid.
Power limit and prosumer status
It is worth emphasising that, regardless of the billing model chosen, the permissible capacity of a prosumer PV installation is still a maximum of 50 kW. Exceeding this threshold automatically excludes the user from the prosumer group and transfers him or her to the generator category, which entails additional administrative and licensing obligations. For this reason, many private individuals and small companies planning an investment select the power of the system so that it does not exceed the 50 kW limit – even if the technical conditions would allow more.
This limit does not only result from legislation, but also from the formal conditions of support programmes and tax credits. In many cases, it is precisely the maintenance of the system capacity within the limits of the micro-installation that is a condition for participation in a given programme.
Subsidy programmes – what you need to know
One of the most recognisable support programmes for individual investors is My Current 6.0, the new edition of which started in September 2024. Initially, it covered installations between 2 and 10 kW, but since August the upper limit has been increased to 20 kW. To receive funding, the installation must have at least 2 kW of power, and additional support is available for the purchase of energy storage, energy management systems and electric car chargers, among other things.
Other forms of support available include, for example, the thermo-modernisation allowance, which allows the investment costs for photovoltaics to be deducted from the tax base. It is valid for installations up to 50 kW. Farmers, on the other hand, can benefit from the Agroenergia programme, which also gives preference to photovoltaic systems that fall within the micro-installation limits. Before investing, it is advisable to familiarise yourself with the current terms and conditions of each programme, as the power limits and required documents may vary from edition to edition and region to region.
Inverter selection and technical aspects of plant performance
The selection of an inverter is one of the key steps in the design of a photovoltaic system. For systems up to 3.68 kW, a single-phase inverter is usually used – cheaper, compact and simpler to install. When the power of the system exceeds this threshold, it becomes necessary to use a three-phase inverter or several single-phase inverters distributed over different phases. This is due to the regulations in force, according to which the power of a generating unit must not exceed 3.68 kW on a single phase. Failure to comply with this limitation results in the grid operator rejecting the application.
It is the responsibility of the investor or contractor to carefully check the available phases and distribute the load in a way that complies with the guidelines of the TNC. Otherwise, the installation will not be connected, even if the other parameters are correct. It is therefore worth determining at the design stage how much power is to be distributed to each phase and selecting the appropriate inverter model.
Oversizing of panels and technical compliance
In practice, the inverter is selected with a certain margin – that is, its nominal power is slightly lower than the total power of the installed panels. Oversizing by around 20 per cent makes it possible to make more effective use of the conditions of variable insolation. The installation works better in the morning and afternoon, as well as in slightly cloudy conditions. At the same time, the inverter is not overloaded at times of peak sunshine.
Any inverter used in Poland must comply with national technical standards, including the requirements of the network codes (NC RfG). The device should have a document certifying compliance with the applicable regulations. Network operators also often expect the inverter to enable remote control – most often via an RS485 interface with the SunSpec communication protocol. Maintaining an adequate level of reactive power is also increasingly required, which improves the stability of the overall network operation.
Safety, measurement and acceptance of installations
Once the installation of the system is complete, it is necessary to take technical measurements and prepare the relevant documentation. This includes checking the insulation resistance, grounding effectiveness and overvoltage protection parameters. In addition, the installation must be equipped with overcurrent and lightning protection – on both the DC and AC sides.
Only after a complete set of measurements and positive acceptance by the installer and a representative of the grid operator can the installation be formally commissioned. The permissible power of a photovoltaic installation is just one of many parameters that must be in accordance with the applicable standards. Without proper technical preparation, even the best-designed system will not be approved for use.
New regulations 2024-2025
A number of beneficial changes have been introduced for prosumers between 2024 and 2025. The amendment to the law of 27 November 2024 reinstated the possibility of billing surplus energy according to the average monthly price (RCEm) for installations connected before 1 July 2024. Users of these systems can also switch to hourly billing (RCE) upon submission of a declaration to this effect. New installations commissioned after this date are covered by the hourly system only. The law also increased the value of the prosumer deposit by 23%, which improves the return on investment in real terms and motivates better management of the energy produced.
In parallel, formal simplifications and new forms of financial support have been introduced. The obligation to obtain a building permit for installations of up to 150 kW has been abolished and, thanks to new regulations, residents of blocks of flats can use energy as so-called ‘prosumer tenants’. Subsidy programmes are also still available, such as ‘My Current’ 6.0, which supports micro-installations from 2 to 20 kW. The amount of support depends, among other things, on the additional solutions used, such as energy storage or management systems. Therefore, the permissible power of a photovoltaic installation should be adapted not only to the technical possibilities of the building, but also to the requirements of the applicable programmes and tax credits – usually limited to 50 kW.
Connection of PV installations to the grid – formalities and requirements
The connection of a photovoltaic installation to the grid requires the completion of certain formalities with the distribution system operator. If the power of the micro-installation does not exceed the connection capacity of the building, it is sufficient to submit a connection application. Along with the form, the technical data of the system and a simplified electrical diagram must be submitted. The operator verifies the documentation and makes the connection without additional procedures. If you are planning an installation with a higher power than the existing connection value, it is necessary to apply for new conditions – this process can take several weeks.
Upon completion of the installation and fulfilment of the connection conditions, a technical acceptance shall be carried out. The operator checks the complete set of documents, including protocols for measurements of insulation resistance, earthing effectiveness and compliance of the equipment with the applicable standards. The inverter and the other components of the installation must have the relevant certificates allowing them to operate in the Polish grid. Formal commissioning of the installation only takes place once all parameters have been approved by the DSO. Therefore, apart from such issues as the permissible power of the photovoltaic installation, the investor must take care of full technical documentation and compliance with the distributor’s requirements.
FAQ – Permissible output of photovoltaic installations
No. In a single-phase installation, the maximum generator output is 3.68 kW. To increase this, it is necessary to switch to a three-phase connection, usually using a three-phase inverter.
No. From 1 October 2023, PV installations of up to 150 kW do not require planning permission. For domestic micro-installations (e.g. 10-20 kW), a notification of work together with a location plan, submitted at least 30 days before installation, is sufficient. A permit is only needed for installations exceeding 150 kW.
No. As a prosumer, an individual can install a photovoltaic system of up to 50 kW. Larger installations (between 50 and 1,000 kW) are considered small installations and can only be carried out by entrepreneurs after meeting additional formal requirements.
In the My Current 6.0 programme, the minimum power of the installation is 2 kW. Support is available for systems between 2 and 20 kW – this limit was increased on 1 August 2024. No subsidy is available for installations below 2 kW or above the set limit.
The connection power is the maximum power that a consumer can draw from the grid. When designing a PV installation, it cannot be exceeded. If the planned system power is higher, an application must be submitted to the operator for new connection conditions. It is only after these have been obtained that it is possible to increase the power of the installation to a level consistent with the current conditions.
Sources:
https://www.gov.pl/web/klimat/korzystne-zmiany-dla-prosumentow-wchodza-w-zycie
https://energa-operator.pl/przylaczenie-do-sieci/przylaczanie-wytworcy-energii/mikroinstalacja
https://enerad.pl/jaka-jest-maksymalna-moc-instalacji-fotowoltaicznej-dla-domu-jednorodzinnego/
https://enerad.pl/instalacja-fotowoltaiczna-jednofazowa-a-trojfazowa-porownanie/
https://fotowoltaikaonline.pl/fotowoltaika-2024
https://www.multienerga.pl/fotowoltaika-blog/moj-prad-6-0-nowa-edycja-2024.html
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