Pricing by system size
Installed cost per kWp falls as system size rises — fixed costs (planning, DNO, mobilisation, switchgear modification) spread across more capacity. Below is the 2026 pricing table from current proposals.
📅 Last updated: May 2026 · Source: 12-month rolling average of our delivered UK office projects
| Office size | System kWp | Panels | Per kWp | Total capex | Payback | What's included |
|---|---|---|---|---|---|---|
| Small managed office | 50-100 kWp | 92-185 | £1,000-£1,200 | £50k-£120k | 4.5-6.0 yr | PV array, 1-2 string inverters, ballasted mounting, DC+AC cabling, G99 application, MCS commissioning, 5yr O&M |
| Multi-let / mid-size HQ | 100-500 kWp | 185-925 | £780-£950 | £90k-£450k | 4.0-5.5 yr | Above + DNO consultation, structural survey, switchroom modification, monitoring portal, IWA-backed warranty |
| Corporate HQ | 500-1,000 kWp | 925-1,850 | £700-£850 | £350k-£850k | 3.8-5.0 yr | Above + battery option modelled, capacity market registration assessment, Scope 2 Disclosure Pack |
| Business park / portfolio | 1-3 MWp | 1,850-5,555 | £640-£780 | £640k-£2.34m | 3.5-4.8 yr | Above + multi-MPAN design, shared battery siting, EV charger integration, ESG portfolio reporting |
Cost by office sub-type
System sizing varies by office sub-type — driven by typical floor area, daytime occupancy pattern, and load profile. The table below is sourced from our `sector-intel.json` for the office-buildings vertical.
| Sub-vertical | Typical system | Project value | Payback (yr) | Annual generation | CO₂ saved (tonnes/yr) |
|---|---|---|---|---|---|
| Corporate Headquarters | 300-1000 kW | £270,000-£900,000 | 6 | 275,000-920,000 | 63-210 |
| Multi-Let Office Buildings | 100-500 kW | £90,000-£450,000 | 7 | 92,000-460,000 | 21-105 |
| Serviced & Managed Offices | 75-400 kW | £68,000-£360,000 | 7 | 69,000-368,000 | 16-84 |
| Coworking Spaces | 50-200 kW | £45,000-£180,000 | 6.5 | 46,000-184,000 | 10-42 |
| Business Parks & Office Parks | 200-2000 kW | £180,000-£1,800,000 | 6.5 | 184,000-1,840,000 | 42-420 |
| Government & Public Sector Offices | 150-800 kW | £135,000-£720,000 | 7 | 138,000-735,000 | 32-168 |
| Professional Services Offices | 60-300 kW | £54,000-£270,000 | 6.5 | 55,000-276,000 | 12-63 |
| Tech & Software Offices | 100-500 kW | £90,000-£450,000 | 6 | 92,000-460,000 | 21-105 |
Finance route comparison
Four funding routes work for UK office solar. We model all four side-by-side in every proposal — the right answer varies with cash position, lease length, balance-sheet preference, and exit strategy. Worked example below: 320 kWp London multi-let, £288k capex.
| Route | Upfront | Monthly / per-kWh | Year 1 tax | 25-yr NPV | IRR | Best for |
|---|---|---|---|---|---|---|
| Cash purchase | Full capex | — | 25% AIA saving | £2.4m | 15.8% | Owner-occupied, capex available |
| Asset finance | £0 | £4.5k/mo (£288k @ 7.5% APR over 7 yr) | 25% AIA saving | £2.0m | 13.2% | Capex-constrained, strong covenant |
| Operating lease | £0 | £3.8k/mo (5-7 yr term) | Lease payments deductible | £1.7m | n/a | Off-balance-sheet preference |
| PPA (15-25 yr) | £0 | 10-13p/kWh (30-50% below grid) | n/a | £1.4m | n/a | Zero capex, multi-let landlords |
What drives cost variation
- Roof condition. Modern flat roofs with good membrane = ballasted install at standard rates. Pitched, listed, or end-of-life roofs add £80-£200/kWp.
- Electrical infrastructure age. Pre-1995 switchgear often needs upgrading — £15-50k extra. We assess as part of feasibility.
- DNO grid constraints. Constrained networks (London UKPN, Greater Manchester ENWL) may require export limitation devices (~£8k) or reduced system size.
- Planning route. Permitted Development = no fee. Prior Approval = £120 + drafting. Full planning + Listed Building Consent = £1,200-£4,500 in heritage settings.
- Scaffolding requirement. Pitched or multi-story roofs need scaffolding — £35-80/sqm of roof footprint.
- Out-of-hours install. Weekend or night work for occupied offices = +20-35% labour rate.
LCOE — the per-kWh number that matters
Levelised Cost of Electricity converts your total system cost into a per-kWh number you can compare directly with grid retail tariffs. UK office solar LCOE in 2026:
- 500 kWp+ system, cash purchase: 5-7p/kWh LCOE
- 100-500 kWp system, cash purchase: 6-9p/kWh LCOE
- Under 100 kWp system, cash purchase: 8-12p/kWh LCOE
- Asset finance route adds: +1-2p/kWh (interest cost)
- PPA route adds: +2-5p/kWh (developer margin)
UK commercial grid retail in 2026 is 25-40p/kWh. Every kWh self-consumed therefore saves 20-30p/kWh net — the gap between solar LCOE and grid retail is the single biggest economic lever in commercial solar.
Hidden costs to budget for
- DNO connection fee. £1,200-£3,500 typical. Reinforcement (rare) £15k-£80k.
- Structural survey. £1,500-£3,200 typical for pre-install verification.
- Building Regs Part L. £400-£800 application fee.
- Insurance premium uplift. Usually nil to £3,000/year — confirm with insurer at design stage.
- EICR refresh. Triggered every 5 years post-install. £600-£1,500.
- Inverter replacement (year 12-15). £35-60/kW. Plan into 25-year cash flow.
AIA, Full Expensing, and the year-one tax saving
For UK limited companies at 25% corporation tax, every £1 of AIA-eligible capex returns £0.25 of tax relief in year one. On a £288k office solar install: £72k of tax saving, reducing effective net capex to £216k. AIA is capped at £1m per business per year — permanent from April 2023.
Limited companies can also use Full Expensing (50% first-year on special-rate pool, of which solar PV is part) — typically less valuable than AIA but useful when AIA is exhausted by other capex.
Partnerships and LLPs can claim AIA but not Full Expensing. For professional-services firms structured as LLPs, the AIA relief is particularly valuable because partner marginal income tax rates (40-45%) are higher than the 25% company rate — making a £1m install effectively worth £400-450k of tax saving.
Common cost questions
How much do solar panels for office buildings cost in the UK?
Installed cost in 2026 ranges from £700-£1,000 per kWp depending on system size, roof type, and inverter spec. A 100 kWp office system typically costs £90,000-£100,000; a 500 kWp HQ system £350,000-£450,000; a 1 MWp business park £700,000-£950,000. We provide fixed-price quotes within 7 working days of receiving your half-hourly meter data.
What's the payback period on office solar in 2026?
5-7 years on cash purchase for most UK offices, 0 years on PPA (cash-flow positive from day one). The exact number depends on your day-rate electricity cost (every 5p/kWh moves payback by roughly 0.5 years), self-consumption ratio (offices typically hit 70-85% without battery), and whether you can claim AIA in year one. Our model is from half-hourly data, not blended-rate assumptions.