100kWp PPA — UK 2026 indicative cost & PPA tariff

2026 indicative numbers

System size	100kWp PPA
Indicative capex (cash)	£82,000–£105,000
PPA tariff (year 1)	14–18 p/kWh
Annual generation	95,000 kWh
Indicative annual saving	£16,150+ (vs 30 p/kWh grid)
Typical audience	Mid-size factories, secondary schools, mid-range hotels, care home groups, single mid-warehouse.
Off-taker requirement	10+ year tenure, £30k+ annual electricity spend, freehold preferred

The point where a PPA starts to make obvious sense

A hundred kilowatts is where the commercial solar PPA stops being marginal and becomes straightforward. At an indicative £82,000–£105,000 to install, this is a system most mid-size factories, secondary schools, care-home groups and mid-range hotels could never justify buying outright while capital is committed elsewhere — precisely the gap a PPA fills. You put nothing down and buy the roughly 95,000 kWh it produces each year at 14–18 p/kWh instead.

Where the generated power goes

Doubling the array from 50 to 100kWp shifts the self-consumption picture. On a single-shift operation some midday surplus will begin spilling to export, so check whether your provider credits those units or whether a Smart Export Guarantee tariff can sit alongside the PPA. The economics still turn on using what you make: the more of that 95,000 kWh you consume behind the meter, the more you dodge at full retail import prices. A battery becomes worth discussing at this size for shifting load into the evening.

Tenure is the gating question

Funders lengthen their horizon as systems grow. For 100kWp expect a preference for freehold or a long lease — commonly ten-plus years remaining — and power spend of at least £30,000 a year. The provider needs two decades of tariff payments to recoup the build, so a tenant who might leave in three years is a poor bet without landlord consent or an assignment clause.

• Freehold or a 10-year-plus lease preferred
• Electricity bills from £30,000 a year upward
• Landlord consent secured on any leased site
• Load profile modelled for realistic self-consumption

Before you shortlist a funder

Read up on the mechanics of an on-site PPA so you know what you are signing, then set it against buying outright or leasing — our side-by-side comparisons lay out the trade-offs. If the credit question nags, the note on what funders look for in an off-taker explains how they weigh it.