Belgian high-voltage grid operator warns for surplus solar power

Belgian high-voltage grid operator Elia is calling for vigilance over solar overproduction. Due to the sunny spring and the large number of solar panels installed, an overproduction could lead to negative prices and a frequency increase, threatening blackouts.

Unlike last year, when this phenomenon occurred mainly in the summer, Elia notes that the risk is already present in the spring.

Overload network

Belgium currently has 11.4 gigawatts of solar panels installed. In two years, this capacity increased by 4 gigawatts, equivalent to the capacity of some nuclear power plants.

Those solar panels can produce up to 9 gigawatts of power at peak times. Hence, the slightest deviation from weather forecasts immediately significantly impacts the balance between supply and demand.

“This can cause negative prices,” Elia says, “and if the imbalance persists, it can result in a frequency increase in Belgium and our neighboring countries.” Blackouts threaten if the frequency of the high-voltage grid (50 hertz) deviates too much.

Of course, there are several ways to maintain grid balance if the yield is higher than consumption at the time and the excess energy flows back into the electricity grid.

For example, in the case of excess capacity, the major market players can turn off generation or activate consumption. Possible negative prices on the imbalanced market also help to encourage such interventions.

But Elia can also intervene by shutting down large offshore wind farms, calling on grid operators in neighboring countries to export additional power, or, in exceptional circumstances, shutting down large solar or wind farms on land.

Dynamic contract

The system operator emphasizes that electricity grid saturation will become increasingly common in the future and that it is, therefore, important to activate sufficient flexibility in the system.

In doing so, Elia is looking at the end user. They could switch to dynamic electricity contracts with hourly tariffs. However, such agreements are only possible in Flanders for the time being – a digital meter is required – and are also a marginal phenomenon with only a few thousand contracts.

In a dynamic contract, the price for the energy cost is usually set hourly based on the process of the power exchanges on which suppliers buy energy for the following day.

In other words, it rewards consumers who adjust their consumption to the availability of (cheap) renewable energy, but controlling solar panels at such times can also offer opportunities.

The grid operator also points to the emergence of smart charging for cars and a Danish project where each device can have a separate meter and thus a separate power supplier—developments that Elia is closely monitoring to implement an efficient market design possibly.

Plug-in solar panels

Anyone in Flanders who still has an analog electricity meter and installs a plug-in solar panel must report this to Fluvius, the electricity and natural gas system operator in all municipalities of the Flemish Region.

As of April 17th, a plug-in solar panel can be connected to the electricity grid in Flanders. This is useful for tenants and people with a limited budget who do not have a roof or garden.

Signers will then have a digital meter installed within three months. Those with a digital meter will not have to register the panels themselves. In Wallonia, however, registration is mandatory.

Flemish Energy Minister Melissa Depraetere (Vooruit) urges the federal government to follow the example of neighboring Belgian countries by limiting solar panels to 800 watts as an extra safety buffer to avoid fire hazards. In practice, that amounts to about two plug-in solar panels per family.