The Clean Horizon team didn’t have time to answer all the great questions from webinar participants live, so we’re sharing the remaining answers with you here.

The presentation from the webinar is here.

1. What about the grid limitations at the DSO level?

It is possible to observe grid limitations at the DSO level as well, which are often a consequence of limitations at the TSO level.

2. Slide 10: is there any guarantee that the TSO will only curtail when absolutely necessary? Or can they still reach the maximum hours per year anyway?                       

They can go up to the maximum every year. However, there are no reason why TSO would limit BESS when it is not required.

3. What happens with grid limitations in Spain, Italy and Poland?            

Similar grid limits are observed in most European countries. However, the type of limitation can differ from one country to another.

4. Are there case studies of grid limitations in the Nordic countries?    

The study was conducted for France.

5. What are the data sources for the grid? Can it be applied to the Eastern European region? 

In the case of France, data sources are for the most part provided by the DSO and TSO. Replicability depends upon the country and the amount of data available.

6. How is the grid limitation profile generated? Could you explain the rationale  and technology used for that forecast?            

The grid limitation was generated randomly, meaning it does not necessarily restrict the storage asset’s injection during a day when there is high solar production.

7. Do you consider grid penalties in your losses f you don’t deliver ancillary services?

We did not consider penalties when estimating losses, as we only accounted for preventive limitations—those that are notified in advance.

8. How does a project protect its grid access capacity into the future ensuring that the TSO doesn’t subsequently or retrospectively grant access to an alternative project?    

Once a grid connection agreement is signed, the grid connection is provided to the counterparty with no potential retrospective change of the granted access.

9. Regarding revenue losses due to network limitations, you mentionlosses between 6% and 17%. However, if you get curtailed during peak hours with high revenue potential, should that 6-17% loss potentially be much higher?     

The study does not consider extreme cases where the asset is prevented from discharging during periods of very high market prices. For example, if the BESS is constrained during an hour when the balancing price reaches 7000€/MWh, the resulting missed revenue could be significant. However, such scenarios are not included in this analysis.

10. What is the limitation notification timing of RTE in France?     

It could be one week in advance or just one hour—it depends on whether the limitation is preventive or curative. For preventive limitations, RTE is required to notify the asset owner before restricting grid access to the plant, whereas curative limitations can occur suddenly without any prior notification.

11. Congestion relief is one  application of BESS. Which European TSOs or DSOs are utilising BESS for this purpose?   

Germany and the UK have already built large-scale BESS projects to handle grid congestion. UK: Pathfinder BESS and DE: Gridbooster.

12. Grid codes, regulation and limitations are strongly country dependent. In which countries is your simulation tool currently active?                 

Our simulation tool is active in all European countries.

France, Germany, Belgium, Spain, Portugal, United Kingdom, Italy, Sweden, Finland, Denmark, Latvia, Lithuania, Estonia, Poland, Bulgaria, Hungary, Romania, Greece, Austria, Ireland, Luxemburg, Norway, The Netherlands, Slovenia, Switzerland, Czech Republic, Japan and more to come.

13. How is discharge limitation the same as charge limitation, on page 16, as there is natural battery leakage? In other words, wouldn’t you lose more discharge revenue than charge revenue as the battery loses charge over longer limitation hours?      

The results obtained are based on the assumptions we used. If we were to consider another scenario with more specific project details and a grid limitation profile adjusted to the location and power plants in the BESS, the results could differ.

14. Slide 16: Does “random” limitation profile mean that limitation was tested in hours without considering that some hours are more likely to experience a grid congestion event than others?

Random limitations mean that we haven’t considered whether the BESS is located next to a PV or wind power plant. For instance, congestion would typically occur around midday if it were next to a PV plant.

15. Slide 20: have there been any talks about FCR or aFRR transitioning from 4-hour blocks or daily products to(quarter-)hourly products?                 

The timeslot duration for ancillary services products depends on the country. France has, for example, 1-hour timeslots for aFRR capacity reservation. The Baltic States are planning to have 15-min products for ancillary services in the future.

16. Is there a certain percentage of BESS penetration in a market at which the market becomes BESS-mature and profitability from energy and balancing markets is significantly reduced?            

Yes, this can be deduced from the merit order shape of the ancillary services. It depends on the country and on the service provided; it is an analysis conducted by Clean Horizon when building the price forecast.

17. Slide 22: where does the 6% of limitations come from? Samuel shared that 6% is the threshold to impact the bankability of a project (the figure is not shared on the slide).

It’s an example of the previously presented case in Slide 23.

18. Slide 23, to which country do the figures apply?               

The figures apply to France.

19. In the case of grid congestion, why can’t the BESS simply be incentivised financially solve the issue?

Yes, this might be a tool to incentivise the storage asset to align its operation with grid constraints. It has already been implemented in France, for instance, through grid fees where a new tariff structure enables BESS to generate revenues when charging during periods of high solar production, especially if located in solar-abundant areas. However, while this is a step in the right direction it won’t fully solve all the grid congestion challenges that will arise with the increasing share of renewables in the energy mix.

20. Generally, wouldn’t it often be the case that the battery would be incentivised to operate in the opposite direction of congestion? For example, if there is a lot of solar generation, the battery would be incentivised to charge rather than discharge?       

Indeed, this is what usually happens when the storage asset is located next to a PV plant. However, in some cases, the asset might be prevented from both charging and discharging during certain periods, which can impact its overall operation. Additionally, even during times of high solar generation, there might be charge constraints depending on the specific area where the project is located.