In recent years the number of prosumers in the distribution grid increased almost three times. However, situations arise when, as the number of generating consumers increases in separate sections of the electricity distribution grid, there is a need to reconstruct the network. With the number of producing consumers growing significantly in the long run, the need for reconstructions may increase accordingly. How is Energijos Skirstymo Operatorius (ESO) looking for ways to avoid such a situation?

Upon receipt of an application for connection to a solar power plant, ESO must assess whether the distribution network at the connection point will be able to receive the electricity produced by it without creating a negative effect on the producer himself or his neighbors. At present, residents tend to choose power plants with a capacity of 10 kW, but it is not always possible to install a power plant without a network reconstruction. Sometimes, the reconstruction may require large investments.

So far, there are not many such cases - from 2020 about 3% of the submitted applications received a response due to network inability to connect additional generation capacities. However, it is predicted that in the long run, as the number of producing consumers grows, this situation may face more customers seeking to become producing consumers. Therefore ESO is looking for the optimal solution: our team of specialists is currently implementing a pilot project, to test the battery storage solution. The battery allows to technologically meet the needs of both producing users and the network.

In the ongoing project, we are investigating whether it is possible for a resident to connect 10 kW power plant to the grid despite the network constraints. In this case, the power plant must not exceed 7 kW of total output power according to ESO parameters, but after using the batteries, the customer can accommodate an additional 3 kW in the batteries. Thus, the actual capacity of the power plant meets the needs of the customer, so it does not lose the electricity generated by the solar power plant. On the other hand, due to the limited power supply to the grid, the power plant together with the battery fulfills all the conditions from the grid voltage quality perspective. In this case, ESO can connect more renewable energy sources without changing its network structure.

The battery as energy storage is a very flexible device. From the perspective of not only connecting producing consumers but also from the traditional consumer who does not have his own generation, they can be exploited for so-called arbitrage - charge at a cheaper night rate when prices are low and discharge for own needs during the day when prices peak. Thus, technologically, the battery would not allow the customer to feel the change in consumption habits, and could in itself become a flexible device in the network, which would reduce electricity costs. In the future, active users with flexible devices will be able to participate in providing system services and receive additional income.

As for today, it is cheaper to generate and feed electricity into the grid than just to store it in batteries. The energy storage system does not improve the payback time of the entire solar power plant and is not yet a financially attractive solution. However, looking to the future, with the expansion of battery functionalities and decrease in their prices, batteries may become not only technologically relevant but also economically beneficial for both solar power plant owners and other electricity consumers.