The Ministry of Defence is building a 40MW solar farm at Larkhill Garrison in Wiltshire, enough to power 13,000 homes and cut 8,000 tonnes of CO2 a year. That is roughly the same carbon saving as taking 3,500 petrol cars off the road.
As reported by GOV.UK, the site will include battery storage, a detail that matters more to the average household than the headline megawatts. Because without storage, even a military-grade solar array feeds the grid at midday and leaves the garrison buying power at 5pm.
What the Army’s project tells us about costs
The Larkhill installation will cost around £40 million, or £1,000 per kilowatt of capacity. That aligns with what Energy Saving Trust now quotes for domestic solar: roughly £4,000-£6,000 for a 4kW system, or £1,000-£1,500 per kW. Five years ago that figure was closer to £1,800 per kW. The price of panels has halved since 2020; inverters and installation have not fallen as fast, but the trend is clear.
For a typical three-bed semi using 3,000 kWh a year, a 4kW system can cover 40-60% of annual demand. At current price cap rates of about 24p/kWh, that is a saving of £600-£900 a year. The payback period: roughly seven to ten years, assuming no export tariff. With the Smart Export Guarantee (SEG) paying around 5-15p per exported kWh, that drops to six to eight years.
But the catch is timing. The Army’s project was announced in 2022 and is only now nearing completion. Grid connection queues are the bottleneck, not the panels themselves.
Who qualifies, and who doesn’t
Most UK homes with a south-facing or east-west roof can host solar. The key constraint is roof condition: if your tiles need replacing in five years, install solar first and then the roofers will charge extra to remove and refit panels. Ofgem’s data shows that 1.3 million homes already have solar, but the potential is 10 million.
For flats or shaded properties, community solar schemes (like those run by Co-op Energy or Octopus) offer a share of a larger array without rooftop installation. The Larkhill model, ground-mounted, battery-backed, grid-connected, is effectively a community-scale project for the garrison. Households in rural areas with land could explore similar setups, though planning permission and grid capacity are hurdles.
What it costs a typical 3-bed semi
A 4kW system with 6-8 panels and a 5kWh battery (like the Tesla Powerwall or GivEnergy) costs roughly £8,000-£10,000 installed. Without battery, £4,000-£6,000. The battery adds £2,000-£4,000 but lifts self-consumption from 30% to 70%, meaning you import less from the grid at peak rates.
Grants are limited. The Boiler Upgrade Scheme covers heat pumps but not solar. The ECO4 scheme can fund solar for low-income households, but eligibility is tight. The best current incentive is the 0% VAT on installations (until 2027) and the SEG payments for exported power.
EPC impact: adding solar panels typically moves a D-rated home to a C, and a C to a B. That can add 5-10% to the property value, according to Nationwide’s 2023 analysis of green mortgages.
Why the Army’s battery matters more than its panels
The Larkhill site will include 20MW of battery storage, enough to shift solar output into evening peak hours. For a home, the same logic applies: a 5kWh battery can store enough to run lights, fridge, and TV through the 6-8pm window when electricity costs 30-40p/kWh under time-of-use tariffs like Octopus Flux.
Without storage, solar exports at midday earn 5-15p/kWh, while you pay 24p/kWh to import at night. The battery flips that arithmetic. The Army’s project proves the business case at scale; the same maths works for a semi-detached house, just at a smaller wattage.
Three things to do now
First, check your roof orientation on Google Maps or via SolarEdge’s design tool. South-facing is best, but east-west arrays capture morning and afternoon sun well. Second, get at least three quotes from MCS-certified installers, prices vary by 30% for the same kit. Third, apply for a grid connection early if you plan to export; Distribution Network Operators (DNOs) are taking 8-12 weeks for domestic applications.
The Army is building a solar farm because it cuts costs and improves energy security. Your home can do the same, but the window for 0% VAT and rising export tariffs won’t last forever.
Frequently Asked Questions
A 4kW system on a south-facing roof in southern England can save £600-£900 a year on bills, depending on your usage and whether you add a battery. With the Smart Export Guarantee, you can earn 5-15p per kWh exported, adding £100-£200 annually.
Most domestic solar installations are permitted development and do not need planning permission, provided panels do not protrude more than 200mm from the roof. Listed buildings and conservation areas require consent. Check with your local council before installing.
