AR8 changes signal lower solar subsidies but stable returns

The next Contracts for Difference auction round, AR8, will slash the maximum price paid to new solar farms by as much as 15%. That is not a retreat. It is a signal that the technology has matured faster than the Treasury expected.

As reported by Solar Power Portal, the Department for Energy Security and Net Zero has proposed lowering the administrative strike price for solar from £57 per megawatt-hour in AR6 to somewhere in the range of £47-52/MWh for AR8. The consultation closes in November; final figures will land in spring 2025.

Who qualifies, and who doesn’t

The CfD scheme is for large-scale generators, think 5 MW-plus solar farms, not the 4 kWp array on a semi-detached in Milton Keynes. But the AR8 changes matter to homeowners for three reasons. First, lower subsidy costs mean the government can allocate more capacity within the same budget, accelerating the grid’s decarbonisation. Second, falling strike prices indicate that solar hardware costs have dropped enough for developers to profit at lower revenues, and those same panel and inverter cost reductions flow through to domestic installations. Third, the signal to investors is clear: the UK is serious about solar at scale, which should stabilise supply chains and keep domestic installation prices competitive.

What it costs a typical 3-bed semi

A typical 4 kWp rooftop system now costs between £5,000 and £7,000 fully installed, down from £8,000-10,000 five years ago. The Energy Saving Trust estimates annual savings of £400-600 on electricity bills for a home using 4,200 kWh/year. Add the Smart Export Guarantee, where most suppliers pay between 5p and 15p per kWh exported, and the payback period falls to 10-14 years, well within the 25-year panel lifespan.

The catch is timing. The 0% VAT rate on solar installations, introduced in April 2022, is scheduled to revert to 20% on 1 April 2027. The Treasury has not confirmed an extension. For a £6,000 system, that is £1,200 extra. Homeowners considering solar should price installations before the 2027 deadline.

What the AR8 changes mean for your decision

Rooftop solar does not depend on CfD subsidies. It competes directly with retail electricity prices, which are around 27p/kWh under the October price cap. Every kilowatt-hour you generate and use yourself displaces a unit you would have bought at that rate. The CfD floor price for large solar gives you a benchmark: if developers can profit at £50/MWh (5p/kWh), your self-consumption at 27p/kWh is a superb margin.

But government policy does affect your options indirectly. If AR8 allocates more gigawatts to solar farms, the grid gets greener faster, which pushes down wholesale electricity prices over time. That could reduce your bill savings slightly, but the effect is small, maybe 1-2p/kWh by 2030, according to Carbon Brief analysis. The bigger risk is that planning delays and grid connection bottlenecks slow deployment, keeping retail prices higher for longer.

For now, the arithmetic favours the homeowner. A 4 kWp system with a battery can cover 60-70% of a typical household’s annual consumption. With the VAT break still in place and SEG rates slowly rising as suppliers compete for exported power, the case for rooftop solar is stronger than it was when CfD prices were £100/MWh a decade ago.

Households considering solar should obtain at least three quotes from MCS-certified installers and compare total costs including scaffolding, inverter replacement (typically £800-1,200 after 10-12 years), and battery options. The Energy Saving Trust’s online calculator gives personalised payback estimates. Act before the VAT deadline, and watch the AR8 consultation outcome in spring 2025 for further price signals.