SMA Solar Technology AG (SMA), the Institute for High Voltage Technology and...

Could PV offer a bit more than just power? That is the question being asked in some recent studies on whether solar technology could help provide ancillary grid services, such as frequency regulation or steady-state voltage control.

September, for example, saw the publication of a report titled ‘Economic grid support services by wind and solar PV’, the outcome of a European project called REserviceS with contributions from companies such as the inverter business SMA, among others.

More recently, SMA Solar Technology has teamed up with Technische Universität Braunschweig’s Institute for High Voltage Technology and Electrical Energy Systems and Gewi, an energy services company, in a research project on how PV can provide balancing power.

To find out more about the initiative, called PV-Regel, PV Insider spoke to Daniel Premm, who is managing the project at SMA Solar Technology.

Q. What was the reason for carrying out the PV-Regel project and what are its aims?

A: Today, the market for balancing power is designed for thermal/fossil-fuelled central power stations. With their growing importance in the global energy supply, renewable energies will take over more and more system responsibility for economic grid operation.

To enable them to do so in the best possible and cost-effective way, research has to start early on.

The aim of the project is to develop suitable technical solutions for photovoltaic systems, ranging from small private systems to large-scale solar power plants, and to demonstrate their feasibility in a field test. We want to show what is possible with PV in this field.

Building on that, it is our aim to give recommendations for the future balancing power market design together with transmission system operators and market participants.

Q. How does this work relate to the REserviceS project?

A: In the scope of the REserviceS project, some research institutes developed and evaluated basic concepts for the provision of balancing power with renewable energies on a European level.

Now, PV-Regel is aiming at technically substantiating the solutions with a special focus on PV, developing them further and evaluating them in a field test.

Q. What kinds of ancillary grid services could PV be used for?

A: In principle, PV systems can contribute to all ancillary grid services.Among the ancillary services delivered by PV systems today include reactive power supply to maintain grid voltage or compensate local reactive power consumption; frequency-dependent control of active power; or dynamic grid support, also known as fault or low voltage ride through.

With the growing importance of decentralised production units, additional functions will be added that will enable those units to secure grid stability on their own.

Those include coordinated reactive power supply, targeted use of active and reactive power for frequency and voltage maintenance, but also black-start capability after grid failure.

Q. Why is it important for PV to be able to offer these services?

A: Typically, these services have been provided by large central coal-fired or nuclear power stations. But our energy supply structures are changing rapidly.

PV will be a major pillar of the decentralised, 100% renewable energy supply of the future and will have to take over system responsibility.

Q. What changes might need to be made to existing PV systems to enable them to offer ancillary services?

A: As previously mentioned, most ancillary services are provided by PV systems already.

In the case of the provision of balancing power, system control and management of PV systems have to be adapted, storage systems have to be integrated in part, and communication possibilities of the PV systems have to be enhanced to integrate them into virtual power plants.

Q. Is it envisaged that these services will be provided with or without battery storage? If without, how will the services be provided and valued, compared to standard electricity delivery?

A: For most of these services, no storage is needed. The use of a storage system can be helpful for the provision of balancing power, but it is not mandatory, at least in times when there is enough solar radiation.

It is part of the project to develop concepts and solutions for the provision of balancing power with PV systems and demonstrate their feasibility in a field test.