The short answer
For UK office buildings of 2,000 sqm or larger consuming >150 MWh/year at current commercial electricity rates, solar PV is almost always economically positive in 2026. Typical payback lands at 5-7 years on cash purchase, with system NPV over 25 years usually 5-7× the capex outlay.
The “almost always” rather than “always” caveat applies in five specific situations: north-shaded rooftops, severely structurally-constrained roofs, very short remaining lease terms (under 5 years) with no tenant green-lease provisions, buildings already due for major fabric upgrades that would conflict with PV install, and listed buildings where Heritage Consent risk is high.
For 90%+ of UK commercial offices, the answer is yes.
Worked-out economics across five building profiles
Profile 1: 1,500 sqm SME office, Manchester suburbs
Annual electricity: 380 MWh / £114k. System: 240 kWp. Capex: £216k. Annual saving: £58k. Payback: 3.7 years. 25-year NPV: £730k.
Profile 2: 5,000 sqm professional services HQ, Birmingham
Annual electricity: 1.2 GWh / £360k. System: 720 kWp. Capex: £576k. Annual saving: £180k. Payback: 3.2 years. 25-year NPV: £2.4m.
Profile 3: 12,000 sqm multi-let office, London (multi-let landlord install)
Annual electricity (landlord areas): 1.8 GWh / £540k. System: 950 kWp. Capex: £760k. Annual saving (service-charge recovery): £198k. Payback: 3.8 years. 25-year NPV: £2.9m.
Profile 4: 3,500 sqm coworking building, Edinburgh
Annual electricity: 850 MWh / £255k. System: 380 kWp. Capex: £342k. Annual saving: £106k. Payback: 3.2 years. 25-year NPV: £1.5m.
Profile 5: 25,000 sqm public-sector HQ, Cardiff (Salix PSDS-funded)
Annual electricity: 3.6 GWh / £1.08m. System: 1,800 kWp. Capex: £1.44m (100% PSDS-funded = £0 net). Annual saving: £356k. Payback: 0 years (grant-funded). 25-year NPV: £6.8m.
Why offices are particularly favoured
Three structural factors make office buildings more favourable for solar than warehouses, retail, or hospitality:
- Demand profile alignment. Mon-Fri 8am-6pm pattern matches PV generation almost perfectly — self-consumption ratios of 70-85% without battery, vs 40-55% on warehouses.
- High HVAC load in summer. Cooling demand peaks exactly when PV generation peaks. Self-consumption ratio rises further in summer.
- MEES 2030 timing. 21% of UK office stock currently sub-EPC-B; landlord MEES compliance creates a powerful additional driver beyond pure ROI.
When the answer is “no”
There are situations where solar doesn’t make economic sense for an office. These include:
- Severely shaded roofs. Buildings in dense city-centre canyons where multiple adjacent buildings block sunlight for 6+ hours of the typical day. Site survey will identify these.
- Buildings due for demolition or major redevelopment within 5 years. Capex doesn’t pay back over short remaining building life.
- Very short tenant lease with no landlord interest. Tenant install needs minimum 7-8 year remaining lease for cash payback; landlord install for service-charge recovery needs landlord engagement.
- Buildings with already-failing roofs. PV install requires sound roof first. If the roof needs replacing in 2-3 years, integrate PV with the roof replacement; don’t install PV on a failing roof.
We turn down roughly 8% of incoming office solar enquiries because the economics don’t work. We’d rather lose the enquiry than deliver a poor-performing install.
Request a free feasibility study — we’ll be honest if your site doesn’t suit solar.
NPV analysis: what the 25-year economics actually look like
Simple payback is the metric most commonly quoted in solar proposals, but it significantly understates the value of solar for long-duration assets. Net Present Value (NPV) at the company’s Weighted Average Cost of Capital (WACC) is the financially correct way to evaluate any capital investment — and for office solar, the NPV picture is compelling.
For a typical 320 kWp office system with 5.5-year simple payback:
Cash purchase NPV at 8% WACC (25 years):
- Year 0 capex: -269,000
- Year 1 AIA tax saving (25% of capex): +67,250
- Years 1-25 annual electricity saving (276,000 kWh at 30p/kWh, 3% escalation): variable, approximately 80,000-178,000/year
- Year 13 inverter replacement: -18,000
- 25-year NPV at 8% WACC: approximately 1.4 million
The NPV-to-capex multiple is 5.2x. For every pound of capex, the project returns 5.20 in present-value terms over 25 years.
IRR comparison: UK office solar at 5-6 year simple payback typically delivers an unlevered IRR of 14-19%. Compare this to:
- FTSE All-Share average total return: approximately 8-9% per year
- UK commercial property: approximately 7-9% per year (highly variable by sector and location)
- 10-year UK gilt: approximately 4.5% in 2026
- Cash deposit: approximately 4.5-5.0% in 2026
On risk-adjusted terms, commercial solar compares favourably with most UK investment categories. The key risk difference is low variance: solar generation follows predictable seasonal patterns, electricity tariffs have historically risen at or above CPI, and technology failure rates on well-installed systems are low.
Five specific office scenarios with worked numbers
Scenario A: 1,200 sqm town-centre professional services, Leeds
Annual electricity: 210 MWh at 31p/kWh = 65,100/year. Available roof: 600 sqm (north-south glazed terrace above reception; 340 sqm usable on flat section at rear). System: 120 kWp. Capex: 114,000. AIA saving year 1: 28,500. Net effective capex: 85,500. Annual saving: 30,240 (self-consumption 92% at this scale — small system, moderate roof). Payback on net capex: 2.8 years. 25-year NPV (8% WACC): 620,000.
Scenario B: 6,000 sqm managed office building, Bristol (multi-let landlord)
Landlord’s electricity (common areas, HVAC, lifts): 680 MWh at 29p/kWh = 197,200/year. System: 540 kWp on large flat roof with no shading. Capex: 432,000. Self-consumption: 74% (landlord areas run 7am-7pm, weekends partly). Annual saving (service-charge recovery from tenants): 116,640. Payback: 3.7 years. 25-year NPV: 2.1 million.
Scenario C: 18,000 sqm HQ campus, Edinburgh (owner-occupier technology company)
Annual electricity: 3.1 GWh at 28p/kWh = 868,000/year. Available roof across three buildings: 7,200 sqm. System: 1,200 kWp. Capex: 900,000 (multiple building connection points, more complex DNO application). Self-consumption 78% (24/7 server cooling load creates very high baseload). Annual saving: 260,000. Payback: 3.5 years. 25-year NPV: 5.4 million. Additional benefit: Scope 2 emissions reduction of 220 tonnes CO2e/year for CDP/SBTi reporting.
Scenario D: 4,000 sqm coworking space, Manchester (high daytime occupancy)
Annual electricity: 780 MWh at 32p/kWh = 249,600/year (high rate on flexible SME commercial contract). System: 290 kWp. Capex: 246,500. Self-consumption 81% (hot-desking drives continuous daytime load profile). Annual saving: 75,108. Payback: 3.3 years. 25-year NPV: 1.6 million. SEG Agile tariff adds a further 4,200/year on export.
Scenario E: 2,500 sqm listed town hall conversion office, Norwich
Available roof: Georgian slate roof, front elevation visible from conservation area. System: 60 kWp on hidden rear flat-roof section only. Capex: 66,000. Annual saving: 17,100. Payback: 3.9 years. 25-year NPV: 350,000. Heritage Consent required but achievable with rear-elevation installation; front-elevation PV refused by conservation officer at pre-application.
What “worth it” actually depends on
Five variables determine whether any specific office solar project is worth it. Understanding each one lets you sense-check any proposal.
1. Self-consumption ratio. The most powerful lever. At 85% self-consumption (typical for a well-occupied office), virtually every well-sited UK office solar project has a sub-5-year payback. At 50% self-consumption (poorly matched demand profile), payback extends to 8-10 years and the project may not meet typical corporate hurdle rates. Ask the installer for the half-hourly modelled self-consumption ratio — not a generic industry assumption.
2. Grid import tariff. At 30p/kWh avoided, solar savings are compelling. At 20p/kWh (possible under long-term fixed-price contracts or green tariffs with low unit rates), savings reduce by a third. Most UK commercial contracts are currently in the 26-35p/kWh range including non-commodity charges. Check your half-hourly meter data to confirm actual unit rate.
3. Finance route. Cash purchase at AIA-reduced effective cost delivers the best NPV for profitable companies. Asset finance creates positive cash flow from month 1 at modest NPV cost. PPA eliminates capex but roughly halves the 25-year NPV. The right route depends on your capex appetite, tax position, and cash-flow priorities.
4. MEES 2030 regulatory context. For landlords with sub-EPC-B assets, solar contributes 4-12 SAP points toward EPC compliance that is now legally mandated by 2030. Treating solar purely as an energy investment understates the true business case — the regulatory risk of non-compliance adds 20-50% to the effective value of MEES-contributing measures.
5. Lease structure. Tenant-occupied buildings require a green lease provision or direct landlord agreement to deploy solar on the tenant’s floor area. For landlord-owned assets with long-term tenants, green lease provisions in standard lease renewals (often accepted without additional negotiation) unlock the full economics. For multi-let buildings with short-lease tenants, landlord-area systems (common parts, HVAC roof) are the primary route and typically still achieve 70-80% of the economics of a whole-building system.
Sensitivity analysis: what breaks the economics
For the worked Birmingham HQ scenario (720 kWp, 576,000 capex, 180,000/year saving):
| Scenario | Payback | 25-year NPV |
|---|---|---|
| Base case (30p/kWh, 78% self-consumption, 3% escalation) | 3.2 years | 2.4 million |
| Low tariff (22p/kWh) | 4.4 years | 1.6 million |
| Low self-consumption (55%) | 4.8 years | 1.3 million |
| Both low tariff and low self-consumption | 7.1 years | 760,000 |
| High tariff (35p/kWh) | 2.7 years | 3.1 million |
| High tariff + battery (85% self-consumption) | 2.4 years | 3.5 million |
Even in the worst-case scenario (low tariff + low self-consumption), the project still delivers a positive 25-year NPV and a sub-8-year payback. For a company with a 10-year hurdle rate, it still clears the bar.
Key takeaways
- For UK offices consuming over 150 MWh/year, commercial solar is almost always economically positive in 2026 — typical NPV-to-capex multiples of 4-7x at 8% WACC
- The five key determinants are: self-consumption ratio, grid import tariff, finance route, MEES regulatory context, and lease structure
- Simple payback understates project value — IRRs of 14-19% on well-sited office solar compare favourably with most UK investment alternatives
- Worst-case scenario analysis still produces positive NPV for most well-sited UK offices — the economics are robust to adverse assumptions
- The 8% of enquiries we turn down share common factors: severe shading, very short remaining building life, or lease terms that prevent cost recovery