Solar Panels for Offices UK: Costs, Savings and What to Check

The daily demand curve of a typical office closely follows the solar generation curve. Staff arrive in the morning as generation rises, demand stays high through the middle of the day when output peaks, and both fall away in the late afternoon.

Several office loads run steadily through working hours:

• Lighting: often on throughout the day, especially in deep-plan floors away from windows
• IT equipment: computers, screens, printers and communications rooms
• Air conditioning and ventilation: cooling demand rises on sunny days, exactly when solar output is highest
• Kitchens and welfare facilities: water heaters, fridges and vending
• Server rooms: where present, these add a constant baseload around the clock

The cooling match is particularly useful. Air-conditioned offices use the most electricity on hot, bright summer afternoons, which is when panels generate most. That means solar output in an office is typically worth the full grid import price rather than a low export rate, and on working days it is often used almost entirely on site. The limitation lies elsewhere: at weekends, on bank holidays and during the summer and Christmas shutdowns, when the building is largely empty.

In a warehouse the roof often exceeds the building's needs. In an office the opposite is usually true. A building with several floors stacks its electricity demand over one roof, and that roof also carries plant, lift overruns and access equipment.

Consider a four-storey office with a footprint of 1,000 square metres and 4,000 square metres of floor space. If around 600 square metres of roof is usable, it might take 100 to 120kWp, generating roughly 95,000 to 115,000 kWh a year. Offices commonly use somewhere in the region of 100 kWh of electricity per square metre of floor a year, so this building might use around 400,000 kWh annually.

Solar would then cover roughly a quarter of the office's electricity, but almost all of its weekday output would be used on site. That makes the payback strong even though the share of demand covered is modest.

The practical lesson is to use the roof as fully as safety and access allow, rather than sizing down. Unlike an ambient warehouse, an office rarely risks generating more than it can use on a working day. The bigger design question is how to use the roof space around plant, rooflights and maintenance routes as efficiently as possible.

Office systems vary with building size and roof type. As a guide, using 2026 commercial prices of around £700 to £1,100 per kWp excluding VAT:

• Small office or converted building, 10 to 20kWp: roughly £11,500 to £24,000, often limited by a small or pitched roof.
• Single-storey office or business park unit, 20 to 50kWp: roughly £20,000 to £52,000.
• Multi-storey office, 50 to 150kWp: roughly £40,000 to £150,000, depending on roof area, plant and access.
• Office campus or headquarters, 150kWp and above: larger roofs, sometimes combined with car park canopies, priced towards the lower end per kWp.

Office installations can cost more per kWp than warehouses of the same size, because roofs tend to be smaller, more obstructed and higher, and city-centre sites can need cranes, road closures or out-of-hours lifting.

Each 1kWp needs roughly 5 to 6 square metres of usable roof. Flat office roofs typically use low-tilt frames, sometimes ballasted, so the roof membrane and structure must be checked. Our commercial solar cost guide sets out what a full quote should include.

Because offices use most of their weekday solar output directly, their payback depends mainly on their unit rate and the share of generation that falls on working days.

Take a 60kWp office system costing £54,000 and generating 57,000 kWh a year. Around five-sevenths of daylight hours fall on weekdays, and bank holidays and shutdowns reduce that slightly, so assume roughly 70% of generation is used on site and the rest exported:

• Used on site: about 40,000 kWh at 26p saves around £10,400 a year
• Exported: about 17,000 kWh at 5p earns around £850 a year

That is about £11,250 a year, a simple payback of under five years. If the building has a server room, weekend security or other loads that continue at weekends, self-consumption and the savings both rise.

Tax can shorten payback further. For a company paying corporation tax at 25%, claiming the Annual Investment Allowance could bring the effective cost of this system to around £40,500. Confirm the treatment with your accountant. Our commercial solar payback guide explains each factor in more detail.

Weekends, bank holidays and shutdown periods are an office's main solar weakness. A system that is fully used on Tuesday may export most of its output on Saturday. There are several ways to deal with this:

• Accept the export: for many offices the weekday saving already makes the case, and weekend exports simply earn a modest Smart Export Guarantee income.
• Battery storage: a battery can store weekend surplus, but it has to wait until Monday to use it, and its value depends heavily on your tariff. For most offices, solar alone is the better investment.
• Hot water diversion: where the building has electric water heating, surplus can be diverted to heat stored water.
• EV charging: staff or fleet vehicles charged during the day absorb solar output, and pool vehicles can charge at weekends.
• Shift flexible loads: some tasks, such as pre-cooling or charging equipment, can be scheduled for sunny periods.

Ask installers to show your expected weekday and weekend self-consumption separately, based on your half-hourly data. A proposal that assumes 95% self-consumption for an office closed at weekends is not realistic. Our battery storage guide explains when storage pays.

When the roof is full, many offices have another option: the car park. Solar carports, or canopies built over parking bays, can add significant capacity on business parks and campuses where the car park covers more ground than the building.

Carports have advantages and drawbacks:

• Advantages: they add generation without using roof space, provide shade and weather protection for vehicles and staff, and pair naturally with EV charging points.
• Drawbacks: the steel structure, foundations and groundworks make them considerably more expensive per kWp than a rooftop system. They usually need planning permission and must be designed around vehicle movements, drainage and lighting.

Other options include wall-mounted panels on south-facing elevations, panels on plant enclosures, and solar on lower outbuildings such as gatehouses or storage blocks.

These extras rarely match a simple rooftop system for payback, but for an office that is roof-limited and has high daytime demand, they can be the only way to cover more of its electricity. Ask installers to price rooftop and canopy options separately, so you can see the cost and benefit of each.

Office roofs bring their own challenges, which affect both cost and design:

• Flat roofs and membranes: most modern offices have flat roofs. Check the membrane's age and warranty, because panels on frames make future re-roofing harder and fixings or ballast must suit the covering.
• Plant and equipment: chillers, air handling units, extract fans and lift overruns take space and cast shadows. Leave maintenance access around them.
• Height and wind: taller buildings experience stronger wind loads, particularly near roof edges and corners, which affects ballast and fixings.
• Structure: ballasted frames can add 50 to 80 kg per square metre, so a structural engineer must confirm capacity.
• Older offices: pitched tiled or slate roofs on older and converted buildings need different mounting methods and take longer to install.
• Fire safety: insurers commonly assess commercial arrays against the RISCAuthority RC62 recommendations, so tell your insurer early.

Our commercial roof suitability checklist covers each of these checks in detail.

Many offices are leased, and many are shared between several tenants, which changes how solar is funded and how its electricity is used.

In a single-let office, the occupier can usually install solar with landlord consent, as long as the lease is long enough for the payback to work. A remaining lease of ten years or more suits a system with a payback of four to six years.

In a multi-let building, the roof and common parts usually belong to the landlord. Common options are:

• Supplying landlord areas: solar powers the common parts, such as lifts, lighting, reception and central plant, with the saving reflected in the service charge.
• Selling to tenants: the landlord sells solar electricity to tenants, which needs metering, billing and suitable contracts.
• Single occupier on a shared roof: one tenant installs and uses the system with the landlord's agreement.

Solar can also improve a building's energy performance certificate rating, which matters to landlords managing compliance and tenant expectations. Read more on our real estate and property portfolios page and in our guide to PPAs versus buying outright.

Most rooftop solar installations on commercial buildings fall under permitted development, so they do not need planning permission. Exceptions can apply for listed buildings, conservation areas and some prominent installations, so check with your local planning authority if your office falls into one of these categories. Car park canopies usually need planning permission.

Funding works the same way as for other commercial buildings:

• Tax relief: the Annual Investment Allowance lets most businesses deduct qualifying spend of up to £1 million from taxable profits in the year of purchase.
• Business rates: in England, eligible rooftop solar is exempt from business rates until 31 March 2035.
• Grants: there is no general grant for private offices in late 2026, though some regional programmes may help. Our commercial solar grants guide explains what is available.
• Finance: asset finance, leasing or a PPA can remove the upfront cost.

Almost every office system above 11.04kW on a three-phase supply needs G99 approval from the network operator, which can take up to 45 working days. Our G99 guide explains the process.

To get proposals you can compare fairly, give each installer the same information:

1. Twelve months of half-hourly consumption data, or at least monthly bills
2. Normal opening hours, weekend use and shutdown periods
3. Roof drawings, the roof's age and membrane warranty details
4. Plant locations and any planned replacements
5. Lease details and landlord consent, if relevant
6. Any plans for EV charging or electric heating

When proposals arrive, check the weekday and weekend self-consumption assumptions, the price per kWp after exclusions, and how the installer will manage lifting and access on a working building. Office installations are often scheduled around occupancy, so ask how disruption will be minimised and whether noisy or high-risk work can be done outside business hours.

Our guide to comparing commercial solar quotes sets out the full checklist, and our commercial solar page covers system options. When you are ready, compare quotes from up to three MCS-certified commercial installers for your office.