Interconnectors are essential to Europe’s grid. They balance supply and demand by moving power across borders.
But Germany’s grid is physically constrained, especially in the wind-heavy north. During oversupply, interconnectors can help by easing the glut, but they don’t solve local congestion. In some cases, they exacerbate the situation.
Batteries, with their ability to store and shift power at the right place and time, are emerging as the essential complement.
1. Germany is the centre of the European power machine
“Some people call the electricity grid in Europe the biggest machine ever built by humankind,” - Lars Stephan, Fluence.
Germany sits at the heart of that machine - a central hub with 20 GW of interconnection with its 11 neighbouring countries.
These links allow countries to share the strengths of their power systems. France supplies nuclear baseload. Norway provides dispatchable hydro. Belgium and the Netherlands offer liquidity. Poland and the Czech Republic absorb excess during tight hours.
Interconnection can act as flexibility - absorbing excess during solar peaks, and supplementing shortages during scarcity.
2. When interconnectors fall short
Interconnectors are designed to keep the system balanced. Most of the time, they do.
When interconnectors help - and when they don’t
On 6 April: prices dropped to –€115/MWh. Germany flipped from 8 GW of imports to 6 GW of exports - a 14 GW swing. Flexibility in action.
On 15 June: prices fell below zero. But imports continued. Prices stayed low. Interconnectors amplified the oversupply.
Even when Germany is oversupplied, some neighbours keep sending power:
- France exports nuclear baseload that must run, regardless of Germany’s needs
- The Netherlands exports surplus solar that’s often cheaper than Germany’s
These flows land on already-congested TSOs like Amprion and TenneT DE - regions managing their own solar and wind peaks.
The result: renewables are curtailed, even as interconnectors run at full tilt.
This is where interconnectors reach their limit
Interconnectors balance markets, not grids. When parts of Germany are physically constrained, cross-border trade won’t solve the problem.
That’s where batteries come in.
3. Interconnectors move energy across borders - batteries move it through time
The chart below is telling.
At first glance, high exports and low prices suggest the system is working. Germany is offloading surplus power when it’s cheap. That’s what interconnectors are for.
But when Germany is exporting at capacity and prices have collapsed, renewables are still being curtailed.
Even when prices send the right signal, power can't reach the border. A sign of a grid that’s over-constrained. Battery storage provides the local flexibility that’s missing.
4. Curtailing renewables isn’t just a waste of clean energy - it’s a missed revenue opportunity
Curtailment presents a choice:
Store the energy and sell it later — or export it immediately to a neighbouring country.
To quantify that difference, we calculated the curtailment value for each day in June - the price that wind and solar could have earned if the system had enough flexibility to absorb it.
We compared that to:
- The maximum German price each day (what a battery could earn by time-shifting)
- The maximum neighbouring price (what Germany could earn by exporting))
Germany’s peak price exceeds neighbouring export prices on over 93% of days.
On average, batteries could have earned 4× more than interconnectors by time-shifting curtailed energy and selling it later in Germany.
The commercial signal is clear: surplus energy is being wasted, while downstream demand is still paying high peak prices.
Deploying storage not only reduces curtailment, it also cuts gas use and strengthens grid resilience.
5. The system needs both - but batteries will lead the charge
Interconnectors and batteries offer complementary value.
- Interconnectors enable continental balancing and access to low-cost imports
- Batteries deliver fast, local, time-shifting flexibility where the grid needs it most
But interconnectors face growing structural hurdles:
- Cross-border approvals can take years - NeuConnect was nearly a decade in the making
- Regulatory alignment across TSOs and countries slows development
- Supply chains for materials are already stretched
Batteries don’t face the same delays:
- Projects in Germany can go from permit to energisation in under 18 months
- They can be sited locally with no need for bilateral frameworks
- And they’re privately financed - backed by business models that already work
The flexibility gap is growing. Batteries are the most effective, deployable solution to ease grid congestion and keep renewables online.
zach.williams@modoenergy.com