Grid issues plague solar’s comeback in Czechia

On April 10, the state-owned Czech Transmission System Operator (ČEPS) was forced to switch off around 400 MW of solar, or about one-sixth of the country’s total PV capacity, in order to ensure power system stability.

“ČEPS decided to activate the curtailment plan after exhausting the normally available operational measures to control the electricity system,” said spokeswoman Hana Klímová.

Normally, the grid operator would dispatch surplus energy to neighboring countries, but that was not possible on April 10, as all potential importers were in surplus. Czechia is now looking to expand its PV fleet on the back of high energy prices and robust subsidies.

“The market itself is moving from residential towards commercial projects. We expect C&I to account for 80% of new projects which is a substantial change, as in past three years we had a 50/50 share,“ said Radek Orsag, CEO of local distributor SolSol. “We expect between 150 MWp to 200 MWp in the residential segment and 600 MWp to 800 MWp in commercial.“

The momentum will build on the fourfold increase seen in 2022, when a total of 289 MW were installed.

“We expect between 800 MW and 1,100 MW of new PV capacity to be added this year,” said Jan Krcmar, chairman of the Czech Solar Association (CSA), adding that first ground-mounted PV projects are getting off the ground after more than a decade of no activity in this market segment.

However, he warns that the Czech grid is not ready to accommodate a growing share of renewables.

“The problem with grid capacity is not a technical (issue), but rather a mathematical one,” he said.

Namely, Czechia does not have a transparent system in which investors can check whether grid capacity is available in a specific location. As a result, they sometimes apply to connect lots of capacity across the country, in order to see where they should buy land. However, this can block up the system.

“These reservations for big PV projects are the reason why some TSOs may refuse to connect more small rooftops even though the large ground-mounted installations may not at all be built,” Krcmar said. “Therefore, large self-consumption in some regions is impossible and TSOs can force customers to install much smaller systems or forbid them to inject any surpluses into the grid under the threat of penalty.”

In some parts of the country, grid bottlenecks are translating into delayed network connections. Specifically, in E.ON-owned EG.D’s network, customers are waiting eight to nine months for PV to be connected. As the payout of the rooftop PV rebate is linked to the connection, many wait almost a year to receive their money. This has a knock-on effect on installers, who are usually only paid after a rebate has been settled.

Asymmetrical mode

Another network-related disadvantage for solar in Czechia is Europe-wide unique phase metering on its low-voltage grid. This requires most inverter manufacturers to implement firmware changes in order to ensure that all solar consumption goes through one phase, enabling a higher self-consumption rate. Not all manufacturers are willing to implement such changes, so a few Chinese manufacturers claim the biggest market share.

“The biggest market share in Czechia in 2022-23 is claimed by GoodWe, Growatt, and Solax. However, due to a limited supply of asymmetrical inverters and their compatible batteries, we have had a shortage in the market,“ said Orsag of SolSol, which reportedly claims more than 30% of the Czech PV market.

It is speculated that running inverters in this asymmetrical mode translates into shorter product lifespans of seven to eight years – ultimately leading to bigger costs for prosumers.

“The official reasons for such an electricity market design is grid stability and that it motivates people not to overwhelm the phases, but the unofficial reason is that TSOs collect grid connection costs and fees from that to the tune of several million euros a year and of course there are electricity merchants that make money off of this,” said Krcmar.

The phase metering could also create a huge imbalance in energy communities that are established on the principle of energy sharing. For instance, in apartment buildings, this would mean that one household could get cheap energy from solar on one phase, and another one would get expensive energy from the grid.

In response to lobbying by the solar industry, the Czech Senate told the Ministry of Industry and Trade to look into the grid design issue and potential changes that might be implemented to overcome such limitations.