UK businesses with grid electricity bills above £15,000/year are increasingly asking the same question in 2026: should we install solar PV or stick with grid-only? The answer for most qualifying businesses is unambiguous — solar wins on lifetime cost, inflation protection, and ESG credentials. The grid still has its place for night-time/weekend consumption, for sites without suitable roof area, and for businesses without capex or asset finance capacity. This page lays out the full side-by-side comparison, the genuine trade-offs, and the decision framework UK businesses should use. For broader buyer guidance see commercial solar buyer's guide and payback by sector.
The headline cost comparison
UK commercial electricity from grid in 2026 costs 24-32p/kWh — this includes the wholesale energy cost (10-14p typically), DUoS distribution charges (4-8p), TNUoS transmission charges (1-3p), Climate Change Levy (CCL, 0.78p in 2026), standing charges amortised per kWh (2-4p), and supplier margin (1-3p). UK commercial solar PV delivers electricity at 4-7p/kWh on a Levelised Cost of Energy (LCOE) basis — the total cost of producing electricity over the 25-year asset life divided by total kWh generated. This is calculated as: (capex + lifetime maintenance) / (system size × annual kWh/kWp × 25 years × degradation factor). The 5-7x cost gap between solar LCOE and grid retail is what makes commercial solar economics genuinely transformative.
Side-by-side comparison table
Below is the full side-by-side comparison of solar PV vs grid electricity for a typical UK SME with 100,000 kWh annual demand.
| Metric | Grid only | Solar + grid |
|---|---|---|
| Cost per kWh | 24-32p (grid retail) | 4-7p (solar LCOE) |
| 25-year price trajectory | 3-5%/year inflation | Fixed at install (~0.5%/year degradation) |
| Year-1 100k kWh cost | £28,000 | £15,000 (residual grid) |
| 25-year total electricity cost | £1,168,000 (compounded) | £725,000 (£100k solar + £625k residual) |
| 25-year saving | — | £443,000 (+ £25k AIA) |
| Upfront cash | £0 | £100k (or asset finance from £0) |
| AIA tax relief year 1 | £0 | £25,000 (Ltd Co @ 25%) |
| Performance risk | None (grid always supplies) | ±5-10% generation variance |
| Maintenance burden | None | £1,000-2,500/year |
| Building value impact | None | +3-7% commercial property value |
| Scope 2 emissions | ~16,000 kgCO2/year | ~3,500 kgCO2/year (78% reduction) |
| Power cut resilience | None | Requires battery + islanding to use during outage |
Why solar LCOE is so much lower than grid retail
The 5-7x gap between solar LCOE (4-7p/kWh) and grid retail (24-32p/kWh) reflects a structural difference in cost composition. Grid retail electricity includes wholesale generation cost (typically 10-14p in 2026), plus network distribution charges (DUoS, 4-8p), plus transmission charges (TNUoS, 1-3p), plus capacity market levy, plus renewable subsidy levies (RO, CfD), plus Climate Change Levy (CCL), plus standing charges amortised, plus supplier margin. Each layer adds cost. Solar PV LCOE includes only the capex amortised over 25 years plus modest maintenance. No grid network costs (because the electricity doesn't travel through the grid for self-consumed kWh). No transmission costs. No supplier margin. No CCL on self-consumed solar. The structural advantage is real and permanent — solar LCOE will always be materially below grid retail as long as electricity is generated on-site and self-consumed.
The grid inflation trajectory matters
UK commercial grid electricity has inflated approximately 8-12% per year compound from 2020-2025 — substantially above CPI inflation over the same period. The 2022 energy crisis drove wholesale prices to 4x normal levels temporarily; while wholesale has retreated, network charges (DUoS, TNUoS, capacity market levies) have continued increasing year-on-year as the UK builds out grid infrastructure for net zero. Forward projection from National Grid ESO + Ofgem 2026-2030: commercial grid electricity expected to inflate 3-5% per year compound. Solar PV electricity is locked in at install with only ~0.5%/year degradation in panel output. Over a 25-year horizon, grid electricity inflation alone makes solar increasingly attractive — even ignoring the absolute cost gap, solar provides inflation protection that's genuinely unavailable from grid procurement strategies.
When grid only still makes sense
Solar isn't the right answer for every UK business. Grid-only continues to make sense for: (1) businesses with annual electricity demand below 20,000 kWh — installation economies of scale aren't strong enough to overcome fixed-cost mobilisation; (2) businesses without suitable roof or land area (no usable south/east/west-facing space, listed building with all roof areas refused, shading); (3) businesses planning relocation within 5 years (solar payback period longer than occupancy horizon); (4) charities and not-for-profits without corporation tax position (can't claim AIA — though PPA route may still work); (5) tenanted premises where landlord won't approve install; (6) businesses with very low electricity demand profile (e.g., overnight-only operations where solar generation doesn't align with demand). For these situations grid-only is the right answer, or a Power Purchase Agreement (PPA) provides solar economics without capex requirement.
Hybrid strategy: solar + grid is the right answer for most
The right answer for most UK businesses isn't solar OR grid — it's solar + grid combined. Most commercial solar projects size to 60-85% of annual electricity demand, leaving 15-40% as residual grid consumption (overnight, weekend, winter peak demand above solar generation). The hybrid approach captures the cost advantage of solar for the majority of consumption while retaining grid as a complementary supply for periods when solar can't meet demand. Typical SME outcome: 78% reduction in grid bill (from £28,000/year to £6,000-£8,000/year on residual grid consumption) plus £1,000-2,000/year SEG export income on solar generation not self-consumed.
Battery storage extends solar's advantage further
For businesses wanting to maximise solar's grid displacement, battery storage extends self-consumption from typical 65-80% solar-only to 90-95% solar+battery. Battery storage time-shifts daytime solar generation to evening or overnight demand, displacing more grid import at retail tariff. Battery also unlocks additional revenue streams unavailable from solar alone: DUoS red-zone peak shaving (£3,000-£15,000/year saving for sites with winter evening demand), Dynamic Containment grid services revenue via National Grid aggregators (£8,000-£25,000/year on 250 kWh+ batteries), and resilience for power cut continuity. See commercial battery storage cost.
The decision framework: solar vs grid vs hybrid
Use this 5-question framework to determine the right approach for your specific business situation. (1) Annual electricity demand? Below 20,000 kWh: grid only. 20,000-100,000 kWh: solar + grid likely strong. 100,000+ kWh: solar + grid almost always strong. (2) Suitable roof area available? Yes: solar feasibility makes sense. No: grid only or ground-mount solar if land available. (3) Corporation tax position? Profitable Ltd Co: 100% AIA materially improves solar economics. Charity/not-for-profit: PPA route or grant-funded purchase. (4) Planned occupancy? 8+ years: solar payback fully crystallises. Under 5 years: PPA route or grid only. (5) Capex or asset finance capacity? Cash: cash + AIA strongest return. Asset finance: zero capex with positive cash flow from month one. No capex/finance: PPA route. Once you've answered these 5 questions, the right finance route and system size become clear.
Recommended next step: side-by-side feasibility
Rather than making the solar vs grid decision in the abstract, get a side-by-side feasibility against your specific situation. Our free 5-working-day desk feasibility models your specific annual demand, current grid tariff, available roof area, corporation tax position, and finance route preferences — delivering a complete comparison of grid-only vs solar + grid 25-year projections with AIA tax relief modelled in. Submit your annual electricity spend and postcode below for a no-obligation comparison report.
Solar panels vs grid electricity — common questions
Is solar electricity cheaper than grid electricity in the UK in 2026?
Yes, materially. UK commercial grid electricity costs 24-32p/kWh in 2026 (including standing charges, DUoS, TNUoS, and CCL). UK commercial solar PV delivers electricity at a Levelised Cost of Energy (LCOE) of 4-7p/kWh over the 25-year asset life — 70-85% cheaper than grid. The LCOE calculation: total system cost (capex + maintenance over 25 years) divided by total generation (25-year kWh output). A typical 100 kW UK commercial solar system: £100,000 capex + £20,000 lifetime maintenance = £120,000 total cost. 25-year generation: 100 kW × 1,000 kWh/kWp × 25 years × 0.85 degradation factor = ~2.1m kWh. LCOE: £120,000 / 2,100,000 = 5.7p/kWh. Compare to grid at 28p/kWh — solar is 5x cheaper per unit generated.
Does grid electricity provide more reliable power than solar?
For most UK commercial sites, no — solar + grid combined provides better reliability than grid alone. UK grid reliability is high (99.97% supply availability typically) but not perfect — typical UK commercial sites experience 1-3 unplanned grid outages per year averaging 1-4 hours each. Solar PV alone doesn't provide power continuity during a grid outage (the inverter disconnects for safety per G98/G99 protection requirements). However, solar + battery storage with islanding capability provides genuine grid-independent operation during outages. Most UK commercial solar systems are grid-tied (solar generation supplements grid, doesn't replace it). For genuine resilience requirements (hospitals, data centres, food processing) battery storage with islanding is essential.
How does grid electricity price inflation compare to solar over 25 years?
UK commercial grid electricity has inflated approximately 8-12% per year compound from 2020-2025 (with material spikes during the 2022 energy crisis when wholesale prices peaked at 4x normal levels). Forward projection: UK commercial grid electricity is expected to continue inflating at 3-5% per year through 2030 driven by capacity market obligations, network reinforcement costs, and ongoing decarbonisation levies. Solar PV electricity cost is locked in at the time of install — system capex amortised over 25-year asset life means LCOE is essentially flat (modest 0.5%/year degradation in output). Over a 25-year horizon, grid electricity inflation alone makes solar economics increasingly attractive — even ignoring the absolute cost gap, solar provides genuine inflation protection unavailable from grid procurement.
Should I lock in a long-term fixed grid electricity contract instead of solar?
Long-term fixed grid contracts (typically 3-5 years) provide short-term price certainty but don't change the underlying market trajectory. UK commercial fixed contracts in 2026 typically cap at 5 years; renewal at year 5-6 happens at then-current market rates. Solar PV provides 25 years of price certainty at fixed LCOE — 5x longer than the longest available fixed grid contract. Strategic businesses use BOTH: a 3-5 year fixed grid contract for the short-term volatility hedge PLUS solar PV for the long-term cost reduction and inflation protection. The two strategies aren't mutually exclusive — they're complementary risk management approaches.
What's the 25-year cost projection: grid only vs solar + grid?
For a typical UK SME with 100,000 kWh annual demand: Grid-only scenario: 100,000 kWh × 28p/kWh = £28,000/year × 25 years × 1.04 inflation = approximately £1.17m of total grid spend over 25 years. Solar + grid scenario: 100 kW solar capex £100,000; year-one bill saves £18,000 (78% self-consumption); residual grid bill £15,000/year inflating at 4%. 25-year total: £100k solar capex + 25 years of residual grid = £100k + £625k = £725k. Net 25-year saving from solar: £445,000. Plus AIA tax relief of £25,000 in year one (profitable Ltd Co at 25% corporation tax) drops effective capex to £75,000 — pushing 25-year saving to £470,000.
What are the practical risks of switching from grid-only to solar + grid?
Six practical risks to assess. (1) Build-out timeline: 10-36 weeks from contract to commissioning depending on system size; you continue paying full grid bills during this period. (2) Cash flow: if cash-purchase route, the £20-£500k+ capex outlay is upfront with savings realised over 5-7 years. Asset finance routes avoid this. (3) Performance risk: actual generation may vary ±5-10% from P50 estimate due to weather, soiling, partial shading. P90 estimate provides downside case. (4) Operational risk: inverter replacement around year 12-15 (£15-25k for typical 100 kW system). Tier-1 manufacturer warranty covers most failure modes. (5) Building sale: solar transfers with building sale — generally adds property value 3-7% on commercial properties. (6) Grid bill won't go to zero: typical commercial site retains 25-40% of original grid bill (overnight + weekend + winter consumption above solar generation).
When does solar definitely beat grid electricity for a UK business?
Solar definitely beats grid electricity for any UK business meeting these criteria: (1) profitable limited company at the 25% main rate of corporation tax (or sole trader/partnership at higher tax band) — enables 100% AIA capture; (2) 8+ year planned occupancy of the building — long enough for solar payback to fully crystallise; (3) annual electricity demand 20,000+ kWh — large enough for installation economies of scale; (4) usable south, east, or west-facing roof area or land available; (5) commercial electricity tariff 22p+/kWh — high enough vs solar LCOE; (6) DNO connection capacity available (G98 for sub-100 kW typically straightforward, G99 above needs constraints check). All six criteria met = solar economics genuinely transformative vs grid-only.