A 1 MW (1,000 kW) commercial solar PV system sits at the utility-scale boundary — the economics are excellent (per-kW capex bottoms out, energy yield is identical to smaller arrays per kW, and the AIA tax shield fully absorbs the capex), but the G99 connection process becomes a 12-36 month project workstream and DNO reinforcement risk is real. This page lays out the real numbers: turnkey cost, panel count, roof or land area, annual generation, sub-vertical fit, finance comparison and a full worked example. For the next size down see 500 kW.
Turnkey cost: £700,000-£820,000 in 2026
A 1 MW commercial PV system delivered turnkey by an MCS-certified installer in 2026 costs £700,000–£820,000, or £700–£820 per kW. This is the 500+ kW pricing band where per-kW economics essentially flatten — module wafer pricing has bottomed, central inverter pricing is at scale-driven floor, and the marginal cost of additional capacity is largely just BoS (cabling, mounting, labour). Variation reflects rooftop vs ground-mount (ground typically 5–10% cheaper per kW once you exclude land cost), structural condition (steel-portal industrial is the gold standard), DNO connection complexity (which can swing £100k+ on constrained networks), and grid form complexity. At this size, the connection cost is often the single biggest variance driver — a project on an unconstrained network with no reinforcement requirement runs £700/kW, while a project triggering a transformer upgrade and substation work can hit £820/kW or more. Always price the connection before quoting.
Modules, inverters and physical specifications
A 1 MW system uses approximately 1,850 modules at 540 W (the de-facto commercial standard in 2026) or 2,220–2,355 modules at 425–450 W. At this scale, large-format modules dominate for labour and BoS reasons — fewer modules means fewer mounting brackets, less DC cable, less labour per kW. Bifacial modules (15–20% generation gain on light-coloured roofs or ground-mount with reflective ground cover) are common at 1 MW scale. Inverter architecture: typically 2–4 central inverters of 250–500 kW each (Sungrow SG250HX, SMA Sunny Tripower CORE2, Huawei SUN2000-HC, or Solis 250-330K). String inverter approaches still appear at 1 MW (8-10 string inverters of 100 kW) for partial-load efficiency, MPPT zoning on shaded sites, or easier serviceability. Three-phase mains essential, typically 1,600A+ supply, often with HV step-up if connecting at 11 kV. Mounting depending on rooftop (K2 Systems, Schletter or Esdec) or ground-mount (Schletter, NCS, GameChange Solar fixed-tilt or single-axis tracker).
Annual generation: ~930,000 kWh in the UK
A correctly orientated 1 MW system generates approximately 930,000 kWh per year on average across the UK. Regional breakdown: southern England 980,000–1,050,000 kWh, Midlands 900,000–950,000 kWh, northern England 850,000–900,000 kWh, Scotland 800,000–880,000 kWh. We model conservatively at 930,000 kWh/year (P50). For ground-mount tracker projects on south-facing sites the figure rises to 1,150,000–1,250,000 kWh per year — 20-25% more than fixed-tilt rooftop. Every site survey includes Solmetric SunEye shading analysis and a full PVSyst yield model with P50 and P90 outputs. At 1 MW scale, the P90/P50 gap is typically 7-10% and the project IRR should be stress-tested against P90 not P50 for finance committee approval.
Annual savings: £170,000-£230,000
Year-one savings on a 1 MW system depend on annual generation (930,000 kWh), self-consumption ratio (typically 65-90% depending on site profile), and the gap between import and SEG export tariffs. At a representative 2026 import tariff of 24p/kWh and SEG export of 10p/kWh (1 MW sites typically negotiate well above the headline 6p), an 80% self-consumption ratio delivers: 744,000 kWh self-consumed at 24p = £178,560 avoided import; 186,000 kWh exported at 10p = £18,600 SEG income. Total year-one savings: £197,160. A higher self-consumption ratio (90%, achievable with 24/7 refrigeration, three-shift production, or battery storage colocation) lifts that to £215,000+. A site with strong daytime demand and a 28-30p import tariff hits £225,000–£245,000. Many 1 MW sites also unlock a small Triad / DUoS reduction (£5-15k/year additional) via the demand reduction at peak.
Worked example: 1 MW food production facility in Bristol
Real-shape project: an 18,000 sqm food production facility in Bristol, 220 staff, three-phase 2,000A supply (existing 1,250 kVA transformer), 24/7 refrigeration plus 6am–11pm two-shift production, annual demand 2,800,000 kWh, current import tariff 24p/kWh. We specify a 1 MW east-west PV array across the unshaded sandwich-panel roof. Capex: £760,000 turnkey (£760/kW). Generation: 880,000 kWh/year (P50, east-west deration, slight inverter clipping). Self-consumption: 92% (810,000 kWh self-consumed, 70,000 kWh exported). Year-one savings: £194,400 avoided import + £7,000 SEG = £201,400. AIA relief: £760,000 × 25% = £190,000 year-one corporation tax saving (sits inside the £1m AIA cap). IETF Phase 3 grant: applied separately for 20% of capex on combined-measure bid (solar + chiller upgrade + LED) = £152,000 grant award. Net effective capex: £760,000 − £190,000 AIA − £152,000 IETF = £418,000. Simple payback: 3.8 years gross, 2.1 years net of all reliefs. 25-year DCF NPV at 7%: £3.6m. IRR: 31.4%. Install timeline: contract to commissioning 64 weeks (40 weeks G99 DNO including reinforcement, 14 weeks lead on central inverters and modules, 8 weeks scaffold and install, 2 weeks commissioning + witness testing).
G99 connection and reinforcement at 1 MW scale
A 1 MW project requires G99 and reinforcement risk is high (50-70% probability on most LV networks). The DNO assessment process at 1 MW: full grid form, single-line diagram, protection coordination study, fault level study, harmonic study, inverter datasheets, plant load profile and worst-case export profile. DNO assessment timeline 16-32 weeks for connection offer. Common reinforcement at 1 MW: 11 kV connection at the substation (£100-300k), new feeder cable upgrade (£80-200k), transformer upgrade (£60-180k), or new metering and protection (£20-60k). Strategies to avoid or reduce reinforcement: G100 export limitation (cap export at 0 kW or low value to avoid triggering reverse-power constraints), battery colocation (use storage to time-shift export off-peak), use contestable works (competitively tender the reinforcement scope yourself to save 20-40%), or apply for a Connection Capacity Agreement / shared connection with adjacent sites.
Finance comparison at 1 MW scale
Four financing routes work at 1 MW. Numbers assume £760,000 turnkey capex, £200,000 year-one savings, 4% bill inflation, 25-year asset life. IETF grant assumed separate at £150k where eligible (food, chemicals, paper, ceramics, metals SIC codes).
| Route | Year-one cash | 25-yr NPV @ 7% | IRR | Best for |
|---|---|---|---|---|
| Cash + AIA + IETF | -£418,000 (net of £190k AIA + £152k IETF) | £3,600,000 | 31.4% | IETF-eligible energy-intensive Ltd Co |
| Cash + AIA only | -£570,000 (net of £190k AIA) | £3,180,000 | 22.8% | Profitable Ltd Co outside IETF SIC codes |
| Asset finance (10y) | £0 capex; £95,000/yr finance vs £200,000 savings = +£105,000 | £2,440,000 | n/a (zero capex) | Cash-flow priority, ownership end-of-term |
| PPA (15y) | £0 capex; PPA price 13p/kWh vs grid 24p = £89,760 saving | £1,380,000 | n/a | Charity, public sector, exit-bound, IETF-ineligible |
For an IETF-eligible site, the combined AIA + IETF stack drives genuinely exceptional returns (31%+ IRR). For non-IETF profitable Ltd Cos, cash + AIA still delivers strong economics. PPA is increasingly competitive at 1 MW because PPA providers prefer the deal size and offer keener PPA price per kWh than at smaller scale. See finance comparison + IETF Phase 3.
AIA at 1 MW: the £1m cap is the constraint
The 100% AIA annual cap is £1,000,000 of qualifying capex per accounting year. A 1 MW system at £760,000 sits inside the cap — but if the company is making other plant and machinery investments in the same year that combined exceed £1m, AIA must be allocated across the projects. At 25% corporation tax, every £100 of AIA-eligible spend delivers £25 of year-one tax relief, so solar PV at 1 MW delivers £190,000 of tax relief on a £760,000 capex. Capex above the £1m AIA cap falls to the standard 18% main pool writing-down allowance — slower relief, lower year-one benefit. Companies planning multiple capex investments should sequence to maximise AIA on the highest-ROI item, which solar PV usually is. See capital allowances guide.
Sub-vertical fit at 1 MW
1 MW fits sites with annual electricity demand in the 1,000,000–2,500,000 kWh range and either 5,500-7,400 sqm of available rooftop or 1.5-2.5 hectares of land. Common sub-verticals: very large distribution warehouses (15,000–40,000 sqm with major forklift fleets), large manufacturing facilities with energy-intensive processes (food production, chemicals, plastics, metals, ceramics, glass — all IETF-eligible), large cold-storage and chilled distribution facilities, regional supermarket distribution hubs, very large hotel and conference resorts, hospital main buildings and trust-wide estate aggregations, large university campuses, data centre support / hyperscale ancillary buildings, and ground-mount projects on brownfield, capped landfill or low-grade agricultural land. If your annual demand is below 800,000 kWh, a 500 kW system has better self-consumption economics. For sites above 2.5m kWh annual demand or with land >5 acres available, multi-megawatt arrays are economically superior.
Choosing an installer for a 1 MW project
At 1 MW the installer due diligence bar is at the maximum commercial level — your installer needs to demonstrate utility-scale project delivery capability. Non-negotiables: MCS Large Scale certification (different scheme from sub-50kW MCS), NICEIC HV electrical contractor accreditation if HV switchgear involved, ISO 9001 + ISO 14001 + ISO 45001 management systems, demonstrated G99 commissioning experience at 1 MW+ scale (at least 3 completed installs in the last 24 months at this size or larger), professional indemnity and product liability insurance at £5m+ each. Beyond accreditations: structural engineer's report, central inverter brand selection with manufacturer SLA, full PVSyst yield with shading and PV loss analysis, sensitivity analysis on P50/P90/P99 yield scenarios, four-metric DCF with sensitivity bands, named project manager + site supervisor + commissioning engineer, references with sites contactable directly, and demonstrated G100/G99 reinforcement avoidance experience. Every tier-1 installer in our partner network hits these markers at the 1 MW band.
Common questions on 1 MW solar systems
How much does a 1 MW commercial solar system cost in the UK in 2026?
A 1 MW (1,000 kW) turnkey commercial solar PV install in 2026 costs £700,000–£820,000, equivalent to £700–£820 per kW. This is the 500+ kW pricing band where per-kW economics flatten — modules, central inverters and balance-of-system reach near-floor pricing. After 100% Annual Investment Allowance on the first £1,000,000 of qualifying capex (which fully covers a 1 MW project), net effective cost for a profitable UK limited company at the 25% main rate of corporation tax drops to £525,000–£615,000.
How many panels are in a 1 MW solar system?
Approximately 1,850 panels at the standard 2026 540 W large-format commercial module, or 2,220–2,355 panels at 425–450 W modules. Most 1 MW projects use 540–580 W bifacial modules for the labour and BoS savings (about 35% fewer panels than 425 W modules). Total array footprint runs 5,500–6,500 square metres of unshaded south-facing roof, or 6,500–7,400 sqm for east-west flat-roof arrays. Ground-mount tracker systems can reduce land area by 30% versus fixed-tilt.
How much electricity does a 1 MW solar system generate per year?
A correctly orientated 1 MW system in the UK generates approximately 930,000 kWh per year on average (930 kWh/kWp). Southern England sites achieve 980,000–1,050,000 kWh; Midlands 900,000–950,000 kWh; northern England 850,000–900,000 kWh; Scotland 800,000–880,000 kWh. We model conservatively at 930,000 kWh/year (P50) for budget purposes. Ground-mount tracker systems achieve 1,150–1,250 kWh/kWp — 20-25% more than fixed-tilt rooftop — with corresponding land area + balance of system cost trade-offs.
Does a 1 MW solar system need a G99 grid connection?
Yes, and at 1 MW you are essentially guaranteed to need G99 with a high probability of triggering DNO network reinforcement. The application process is the same as G99 for smaller systems but with stricter protection settings, more detailed network impact assessment, and 24-36 month total timelines common on constrained networks. Application fees £5,000–£60,000+ depending on assessed reinforcement. Many 1 MW projects use G100 export limitation (capping export at 0 kW or low value) to avoid reinforcement requirements and accelerate connection timelines. Full G99 process + G100 export limitation.
What is the payback period for a 1 MW solar system?
Simple payback for a 1 MW commercial PV system in 2026 lands at 4–5 years on gross capex, or 3–3.7 years on AIA-adjusted net capex. Typical year-one savings: £170,000–£230,000 depending on import tariff, self-consumption ratio and SEG export. After AIA, a £760,000 install nets to £570,000 effective capex. With £200,000 annual savings, simple payback hits 2.85 years on net capex, or 3.8 years on gross. 25-year DCF NPV £3.2–4.5m on a typical 1 MW site.
How much roof or land does a 1 MW solar system need?
A 1 MW rooftop array needs approximately 5,500–6,500 sqm pitched south-facing or 6,500–7,400 sqm east-west flat-roof. Most rooftop 1 MW projects use very large industrial roofs (typical 15,000–40,000 sqm distribution or manufacturing roofs). Ground-mount fixed-tilt needs 2.0–2.5 hectares (5–6 acres); single-axis tracker needs 1.5–2.0 hectares (3.7–5 acres). Brownfield and capped landfill sites work well — flat, secure, low alternative use value. Greenfield agricultural land typically requires planning permission above 50 kW.
What businesses typically install a 1 MW solar system?
Sub-vertical fit for 1 MW: very large distribution warehouses (15,000–40,000 sqm with major forklift fleets), large manufacturing facilities with energy-intensive processes (food production, chemicals, plastics, metals, ceramics, glass), large cold-storage facilities, regional supermarket distribution hubs, very large hotel resorts, hospital main buildings and trust-wide estates, large university campuses, data centre support / hyperscale ancillary buildings, and ground-mount projects on brownfield, capped landfill or low-grade agricultural land. Annual demand typically 1,000,000–2,500,000 kWh.