Interconnector: how it changes your capture price

An interconnector changes the price signal reaching a renewable project by joining two bidding zones. When electricity can flow from a cheaper zone to a dearer one, the price gap narrows. Your project then earns against a different distribution of hourly prices than it would in an isolated market.

That is the part a capture-price assumption often hides. The cable does not give a wind or solar project a fixed premium. It changes the hours in which the project is exposed to a high or low price, and the effect depends on flow direction, available capacity and the project's generation profile.

What does an interconnector do to a renewable project's capture price?

A capture price is the generation-weighted average market price received by a project. A solar project gives more weight to daylight prices. A wind project gives more weight to the hours in which its turbines produce. The project capture price therefore differs from the simple average of all hourly prices.

Where the two bidding zones are coupled under the relevant market and capacity-allocation arrangements, the interconnector makes cross-border capacity part of the price calculation. If the receiving zone has a shortage while the sending zone has spare generation, the resulting flow can reduce the receiving-zone price relative to a no-flow case and raise the sending-zone price relative to its unconstrained surplus. The spread narrows when those market conditions apply and the connected networks do not impose a binding constraint elsewhere.

The effect reverses when the flow direction reverses. A project on the exporting side can see low-price surplus hours supported by demand across the border. A project on the importing side can lose some of the scarcity uplift that would otherwise have raised its price. The same interconnector can therefore improve one project's capture price and reduce another's.

An interconnector is a transmission asset, not a contract for a renewable project's output. It does not remove local congestion behind the bidding-zone boundary. It also cannot move power when the cable or the connected network is unavailable.

Why does the day ahead market matter more than the annual average?

The day ahead market sets the price used for many schedules before delivery. An interconnector participates in that cross-border coupling by making available transfer capacity part of the market calculation. The hourly result is what matters to a renewable project, because generation is uneven across the day and across seasons.

An annual average can rise while the project's capture price falls. That happens when the hours in which the project produces become cheaper, even if prices in other hours increase. Solar is exposed to the shape of daytime prices. Wind is exposed to a different and more weather-driven shape.

Read the price series beside the generation profile. Then compare three cases: the zone before cross-border exchange, the coupled day ahead price, and the project's generation-weighted result. A capture-price assumption that uses only an annual wholesale average has discarded the mechanism that decides the revenue.

What changes in the balancing market?

The balancing market operates closer to delivery and settles deviations and balancing actions under the market's local arrangements. Interconnector availability can affect the options available to system operators and the value of flexibility across a border.

That does not turn balancing-market prices into a second day ahead capture price. A renewable project still needs a model of its forecast error, imbalance exposure, route to market and contractual settlement. The interconnector is one condition in that chain. Its day-ahead effect and its balancing effect belong in separate inputs.

The practical constraint is time correlation. A cable may be available when a project produces, unavailable during a maintenance period, or constrained by flows elsewhere in the connected networks. A yearly assumption can hide all three.

What does Noda's screening record show about the evidence gap?

Noda's saved-site aggregate for 5 July to 10 August 2026 contains 77 runs. Solar PV accounts for 1,373 MW across 28 runs, but the record describes sites users drew and saved, not a population of screened projects; only 19 of the 77 have a published report behind them. That aggregate shows the technology mix in the record. It does not measure capture-price spreads.

The screening record available for this article does not publish a split of capture-price assumptions across sites. The effect of an interconnector must therefore be established from the project's hourly production series, the relevant bidding-zone prices, the cross-border capacity and availability data, and the route-to-market terms. A preliminary screening report can flag that these inputs are missing. It cannot replace the market model or the operator's study.

Who owns the interconnector, and who should you ask for evidence?

Ownership and operation are separate questions. A transmission owner or interconnector licence holder may own the asset, while transmission system operators and market operators provide the operational and market arrangements. The answer is country-specific.

Ofgem describes interconnectors as cables on land or under the sea and the substations they connect. Its electricity interconnectors page, read on 21 August 2026, lists consultations and guidance for the Great Britain market. NESO publishes information on energy markets, system operation and balancing for Great Britain. In another European market, use the relevant transmission system operators and national regulator.

For a project appraisal, request the historical and forward-looking evidence that can move the assumption:

• hourly day ahead prices for the project's bidding zone and the connected zone;
• interconnector transfer capacity, outages and the periods in which cross-border capacity was curtailed;
• intraday and balancing-market treatment, including the project's imbalance settlement;
• the generation profile used for the project capture-price calculation; and
• the PPA or route-to-market definition of the price against which the project settles.

The European market's cross-border methodology is described by ENTSO-E's Capacity Allocation and Congestion Management page, read on 21 August 2026. The page explains that cross-border capacity is calculated with system-security constraints in view and that the process covers day-ahead and intraday coupling. That is why a nameplate interconnector capacity is not the same as hourly capacity available to your revenue model.

What should an investor challenge in the capture-price model?

Ask the model owner to show the hourly multiplication, not only the resulting average. The model should expose which hours carry the project's output, which price series it uses, how it treats missing or negative prices, and whether it assumes the interconnector is always available.

Then change one input at a time. Remove cross-border capacity from the producing hours. Apply the observed outage series. Replace the day ahead price with the contracted PPA settlement definition. Recalculate the project's weighted result. The movement between those cases is the interconnector exposure.

For an investor, the relevant question is the distance between the base case and the first case that a transmission outage, zonal spread or contract term makes plausible. Investors assessing renewable project risk need that movement in the downside case, not a single capture-price number in the headline case.

The same hourly evidence also affects how curtailment is put into a project valuation. Redispatch and cross-border flows can interact with local constraints, but redispatch costs and who pays them are a separate question from the price received for energy that is actually sold.

The rule for an interconnector in your revenue model

An interconnector changes the hourly price distribution, so your capture-price assumption must change with the project's hourly generation and the cable's available capacity.

Start with the developer's generation profile and the exact price basis in the PPA or route-to-market agreement. Have the market modeller join it to day-ahead, intraday and balancing inputs. Have the investor test outages, congestion and the loss of the cross-border price effect. Keep the evidence date beside every series.

The captured figure in this article is from Noda's saved-site aggregate, not a capture-price forecast. Noda's screening is a preliminary risk report and does not replace an official grid study or a project-specific market model.

This article was written automatically from Noda's own screening data and checked against the official sources it cites. Editorial responsibility rests with Noda.