Such are the energy losses in the Polish transmission grid. Opposing forces clash.

• The loss ratio in the Polish transmission network in 2023 was 1.59% and in 2024 1.63%, which meant that the annual amount of electricity losses was 1.62 TWh in 2023 and 1.70 TWh in 2024.
• - Based on the performance after three quarters of 2025, the initially estimated loss ratio for 2025 is 1.64%, and the volume is similar to that performed in 2024 - the press office of Polskie Sieci Elektroenergetyczne told the WNP portal.
• Some current phenomena result in a reduction of transmission losses (e.g. reduction of transmission distances as a result of the development of distributed generation), while others contribute to an increase in these losses (e.g. increase in cross-border exchange).
• What could be the level of losses in the transmission grid after 2025? Commenting on this issue, PSE indicated, among other things, that more and more energy will be delivered to consumers directly from the distribution grid, and on the other hand, energy will appear from offshore wind farms, transmitted from the north to the south of Poland.

The flow of energy through power grids is accompanied by energy losses.

We asked Polskie Sieci Elektroenergetyczne (PSE) , the operator of the Polish electricity transmission system, what their so-called balance difference (losses in the transmission network) was as a percentage of the energy fed into the grid.

The balance difference generally consists of technical losses, i.e. losses arising during energy transmission due to the physical transformation of electrical energy into heat, and commercial losses.

Up to 1.7 TWh of energy lost in transmission networks

- The loss ratio in the transmission network, which is the share of the balance difference in energy fed into the transmission network, amounted to 1.59% in 2023 and 1.63% in 2024. The annual volume of losses in these years amounted to 1.62 TWh in 2023 and 1.70 TWh in 2024, respectively - the PSE press office told WNP.

These 1.7 TWh account for approximately 5% of the electricity supplied to households in 2024 (according to the Energy Regulatory Office report, the volume of electricity supplied to households in 2024 amounted to less than 32.41 TWh).

What could the transmission grid losses be this year? We received information from PSE that after the first three quarters of 2025, the preliminary estimated electricity loss rate in the transmission grid for 2025 is 1.64% , with the volume of losses similar to that incurred in 2024.

PSE, according to the information obtained, purchases energy to cover transmission losses on the Polish Power Exchange.

The company notes that energy losses at the transmission grid level are relatively low, which results from the laws of physics – the higher the voltage, the lower the losses. The operator states that it is systematically expanding the 400 kV grid, thereby reducing the role of the 220 kV grid.

- Losses are also influenced by, among other things, the network configuration, the location of connection points for generating sources and points of energy collection from the network, and the volumes and directions of cross-border exchange, which has increased in recent years - commented PSE.

Distributed photovoltaics reduces energy losses, cross-border exchange increases

The company's press office indicated that all the above factors and the change in the energy mix (reduction in the volume of energy generated in conventional sources and increase in production in renewable energy sources) cause changes in the directions of power flows in the National Power System (KSE), which results in the variability of the volume of the balance difference in the transmission network.

The operator explains that some of the occurring phenomena result in a reduction of the balance difference – for example, reducing transmission distances as a result of the development of distributed generation, while others cause increased flows and consequently contribute to increased losses in the transmission network, for example, increased cross-border exchange and the implementation of international transit via the national transmission network.

- As a consequence, the annual volume of the balance difference has stabilized at the level of 1.6-1.7 TWh over the last three years - the PSE press office told the WNP portal.

Transmission network losses after 2025 are difficult to predict

We also asked PSE what levels of balance difference (as a percentage of energy fed into the grid) they expect in the coming years, after 2025.

PSE, emphasizing that the level of losses in the transmission network is the result of many factors mentioned above, indicates that on the one hand, with the development of distributed energy, an increasing volume of energy will be delivered to consumers directly from the distribution network, but on the other hand, in the coming years, energy from offshore wind farms will appear in the National Power System and it will be transmitted from the north to the south of Poland, to the places of its reception.

- Taking into account the specific nature of the national transmission network and the influence of other factors, it is not possible to indicate the forecast level of the balance difference in the coming years - commented the operator.

PSE manages the highest-voltage grid in Poland, including over 16,000 km of lines and 110 substations. Currently, PSE is implementing the largest investment program in its history. The operator states that within a decade, nearly 5,000 km of 400 kV lines and 28 new substations will be built, and 110 existing substations will be modernized.