Curtailment Costs Surge in Scotland: What It Means for Your Rental Payments

Wind farm curtailment in Scotland is becoming a critical issue for landowners. As grid congestion rises and constraint payments hit record levels, many site hosts are discovering gaps in their renewable energy lease payments.

In the first half of 2025, Scottish wind farms were paid to switch off nearly 40% of their potential generation because National Grid was unable to carry the power south.

According to the Financial Times, Scotland accounted for 86% of the UK’s lost wind energy in that period. That breaks down to about 4 terawatt hours (TWh) of lost renewable energy and £117 million in compensation payments to developers. (For scale, 4 TWh could power every home in Glasgow, Edinburgh, Cardiff, Newcastle and Southampton for almost four years.)

While this kind of thing is often portrayed as just a technical problem with the grid system, its real-world impact reaches deep into landowner income streams. For those hosting wind projects on their land, every lost megawatt-hour may reduce rental income payments – unless the lease has been drafted to protect against it.

In this blog post, I’ll cover why curtailment is rising and how it could affect your income. I’ll also tell you how to spot when a constraint is taking place on your site (because it isn’t always obvious). Lastly, I’ll outline how to turn constraint into an opportunity and offer recommended steps you can take to protect your income and your land.

Let’s get started.

Why Wind Farm Curtailment Is Rising in Scotland

Curtailment happens when turbines must be powered down because the grid can’t absorb more electricity.

There are several reasons for this:

• Grid bottlenecks: We have an old electricity system with many legacy power stations in the north of Britain. But the electricity is needed in the south of England. The latest constraint map from the National Energy System Operator (NESO) shows the persistent north-to-south pinch points where the grid must ‘redispatch’ power to stay within the safe limits.

• Maintenance outages: NESO’s 2025 Balancing Costs Report highlights how planned works on Scottish circuits, coinciding with windy conditions, increased congestion and drove up thermal constraint costs. Thermal constraint costs are the expenses NESO incurs when too much electricity is trying to flow through the grid’s infrastructure. Its upgrades result in higher dispatch bills in the short term.

• System design lag: The UK Energy Research Centre (UKERC) points to transmission network unavailability as a quiet but growing driver of curtailment – “turning wind down in Scotland and replacing it with gas generation in the south”.

Curtailment is beginning to take its toll. The Renewables Now summary of Montel data puts total curtailed energy across Great Britain and Ireland at 5.5 TWh in H1 2025 – a 30 per cent jump on the previous year. (For context, 5.5 TWh could power every home in Birmingham, Manchester, Leeds, Liverpool, Sheffield, Bristol, Nottingham and Leicester for nearly three years.)

The Income Connection

For landowners, the commercial question is straightforward. When the grid tells turbines to stop, does your rental income stop too? The answer: it depends on your rental model.

Different types of rental models

Most renewable leases fall into one of three models:

Do you need a refresher on rental models? Read about payment arrangements for wind farms in our dedicated blog.

How your rental income is affected

If your rent is linked to your site’s performance, every time National Grid asks you to stop producing electricity can chip away at your rental income. The precise wording of your lease and the method used to calculate your rent will determine whether that loss of income is shared or absorbed by your wind farm developer and/or you.

It’s also important to note that many older leases don’t include information on constraint payments – also known as the compensation developers receive from NESO whenever National Grid asks a wind farm to stop producing electricity. Where a lease does not clearly address this issue, wind farm developers are likely to keep all curtailment income generated, and landowners will likely receive less rent.

But you have options. Landowners should urgently review their leases to determine how curtailment income should be accounted for, and then request any outstanding curtailment rent.

This is because landowners who have failed to identify and request this additional income may be deemed to have unknowingly or tacitly agreed with their developer that this income should be excluded from rental payments.

Detecting When Curtailment Happens on Your Site

Curtailment isn’t always noticeable. Unless you have access to real-time operational data, you might assume that electricity production fell short due to factors like scheduled maintenance or poor wind conditions.

This is where independent auditing becomes vital. Our dedicated blog on managing and monitoring wind farms shows how audits reconcile operator reports with NESO dispatch records to reveal hidden losses. Arrange an audit to ensure you’re getting the most value from your site.

Tools such as our Lumify SiteView360™ compare your site’s expected generation against actual metered data and grid instructions. It flags anomalies that may indicate unreported curtailment or underpayments in turnover rent – helping ensure landowners are paid correctly.

Turning Constraint into Opportunity: Storage and Extensions

There is a silver lining. The same bottlenecks that cause curtailment have accelerated interest in battery co-location.

NESO’s Local Constraint Market (LCM) invites flexible assets in Scotland – including batteries – to help relieve boundaries, creating new income streams and reducing curtailment.

Policy signals are pointing the same way. According to the DESNZ Energy Storage Roadmap 2025, Britain’s grid-scale battery capacity is set to triple by 2030, supported by reforms to the Capacity Market.

For landowners negotiating lease renewals, co-locating storage or agreeing shared-benefit clauses can stabilise income and improve project bankability. Our guide on wind farm extensions explains how repowering and storage integration can boost site performance by as much as 170 per cent while freeing up acreage for other uses.

What Landowners Should Do Now

What steps can you take to insulate your site from potential curtailment issues? Here are several I recommend.

Review your lease

Check whether your rent calculation is exposed to curtailed output and whether compensation payments are shared.

Plan mid-lease reviews

If you decide you’d like to update your lease terms, or even if you don’t, it’s always worth booking in a mid-lease review. This will allow you to renegotiate if market rents or project performance diverge sharply from your expectations. It further enables you to update definitions, metering references and indexation. Our blog on lease agreements and mid-lease options outlines what to include.

Audit regularly

Commission an independent performance and payments audit every three to five years to reconcile metered data with NESO dispatch and operator statements.

I typically see meaningful discrepancies uncovered during detailed reviews, which is evidence you can take to the negotiating table. Tools such as our Lumify SiteView360™ can help you spot underpayments.

Consider co-location

Batteries or flexible assets can monetise curtailed energy, reduce constraint loss and may open up new value streams (like the Local Constraint Market). Analysis suggests smarter deployment could cut UK curtailment costs by approximately 80 per cent.

Stay informed

Follow constraint trends via NESO’s open data and Ofgem’s Connections Action Plan to time your negotiations. During any lease negotiations, you’ll be at the ready with an up-to-date context on connection queues and boundary upgrades.

The Bigger Picture

Curtailment is the cost of progress. It shows that Britain is generating more clean power than its current grid can handle. But for landowners, that progress pays off only if leases, audits and negotiations keep pace.

At Lumify Energy, we can make the process as simple and transparent as possible. So you can protect the full, fair value of your renewable assets even as the energy system evolves.