Market access

Virtual power plants to allow prosumers to access the electricity market in Croatia

The law in Croatia allows households with solar panels to bundle and market excess energy, although the technical solutions are still too expensive. The country’s first virtual power plant, or aggregator, now paves the way for the aggregation of smaller, geographically dispersed energy sources, while there will also be other options for prosumers.

Participants of a webinar on virtual power plants as a new factor in the energy market presented the concept of Croatia’s first virtual power plant, recently inaugurated by KOER, and raised the issue of the growing number of households that have rooftop solar panels as well as small and large battery systems.

A virtual power plant is a cloud-based distributed power plant that aggregates the capacities of distributed power sources and enables increased power generation, trade, and power sales. The definition is complicated for amateurs, which is why the event was organized to describe the concept to the public.

The technology allows the operator to unify the available electricity sources, but also to reduce energy consumption in the event of grid overload, such as when a sudden change in weather conditions weakens the production of solar parks and wind power plants. Its role is to help balance production and consumption. Free capacities such as diesel aggregates are activated to boost production or, if not, a plant in the system can temporarily stop to reduce its consumption.

Artificial intelligence will have an increasing role in preserving the stability of the electricity system and optimizing surpluses

It is not a power plant in the physical sense, but an aggregator – specialized software enables automated capacity management, where it must centralize, analytically process and display data and enable communication with the transmission system operator of electricity.

Experts who spoke at the webinar agreed that with the increase in the number of small power generators, the introduction of battery systems for energy storage and the penetration of electric vehicles, the artificial intelligence would play an increasing role in preserving the stability of the electricity system and optimizing surpluses.

As virtual power plants have technical possibilities and a legal basis for the inclusion of small rooftop solar panel systems in the market, this could become a course of development and motivate households and small businesses to become prosumers as well. just add their batteries to the system.

Photo: KOER

Virtual power plants are like pumped storage hydroelectric power plants

KOER director Marko Lasić compared virtual power plants with pumped-storage hydropower plants. “A pumped-storage hydroelectric plant can supply energy to the system and it can draw energy from the electrical system. Unlike a conventional power station, which is a physical unit in one location, a virtual power station simultaneously manages a group of distributed consumers and sources to achieve the effect of a conventional power station – taking and supplying energy “, did he declare.

With regard to the available capacities that can reduce electricity consumption on demand, it is as if a real power plant were activated to cover a shortage of electricity. These partners are paid for the service.

An aggregator simultaneously manages a group of distributed consumers and sources to achieve the effect of a pumped-storage power plant – taking and delivering energy

When KOER established its virtual power plant, it said that it provided the consumption reduction service for the Croatian transmission system operator (HOPS) and that it would later introduce the consumption increase service in the event of an unexpected increase in supply, which can also cause problems in the power supply system.

The cost of integrating an industrial plant is currently around 4,000 euros, although some newer and more digitized sites are easier to connect, Lasić said. According to him, integrating small prosumers is still not profitable, but bringing them together can help.

Preparing for a 100% renewable electricity system

The concept of the last decades that production and consumption must be equal at all times is partly changing with the increase in the share of renewable energy, as this increases unpredictability, according to HOPS deputy director Antun Andrić, in in charge of the market department. He explained that the company contracts reserves from grid users and activates them when it needs to balance the system as well as keep the frequency stable.

Eventually, HOPS will need to secure 100% of ancillary grid services from renewable electricity, whether from independent entities or through aggregators, Andrić pointed out.

There are several legal solutions for prosumers to access the market

When it comes to distributed flexibility, national distribution system operator HEP ODS has an important role, he added, and suggested that upcoming regulations could allow rooftop PV owner groups to directly offer to the company the auxiliary voltage regulation service at the local level, without an aggregator. It is possible that these entities will gain direct access to the wholesale market or work with suppliers or other participants, Andrić said.

Market access for small PV systems is the responsibility of the Croatian Energy Market Operator (HROTE) and depends on future regulations, he added. Andrić suggested that one opportunity lies in the creation of energy communities, which the law allows. There are other models in the law that make market access possible for prosumers: active buyer group, renewable energy community, independent aggregator and supplier who can be an aggregator, he noted.

Virtual power plants should become brokers in the electricity market

President of the Eko Kvarner civic association, Vjeran Piršić, pointed out that there are more than 150 such units on the island of Krk and that groups of small photovoltaic systems must play a role in the market. The island has long stood out among Croatian regions, not only in the solar panel segment, but also in waste management and other forms of environmental protection.

Piršić revealed that during the webinar, his solar panels produced eight times more electricity than the household consumption and the batteries were full. He argued that he would like the ability to sell the surplus.

Lučijano Sangaleti, business development manager at Končar – Digital, said the residential sector has great potential for aggregation, including home and automotive batteries. Moreover, virtual power plants should become brokers in the electricity market, he said.

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