Blog · Published 2026-05-12

Multi-site commercial solar rollouts: 2026 best practice

UK commercial solar at portfolio scale — retail chains, hotel groups, multi-academy trusts, logistics REITs — operates on fundamentally different economics from single-site projects. Framework procurement, programme management, standardised technical specifications, and consolidated finance all materially shift the cost-per-kWp. This post covers the playbook proven by major UK commercial solar rollouts.

Why multi-site differs economically

Multi-site commercial solar at scale (50+ sites) achieves 15-30% lower £/Wp than single-site equivalents. Drivers:

1. Framework procurement. Single competitive tender + framework agreement vs individual tenders per site. Typical framework price: £0.75-£0.85/Wp on 100kWp average sites vs £0.95-£1.10/Wp single-site.

2. Standardised technical specification. Single panel/inverter/mounting combination across the portfolio. Simplifies design, procurement, monitoring and O&M.

3. Programme management overhead. One programme manager across the portfolio vs individual project managers. £4,000-£8,000 per site saved.

4. DNO coordination. Centralised approach to G99 applications. Some DNOs offer 'multi-site' processes that materially reduce per-site lead time.

5. Finance pricing. Portfolio-scale debt or PPA pricing typically 50-100 bps better than single-site. Material on £5m+ programmes.

6. Insurance pricing. Group commercial insurance with solar declaration is materially cheaper than per-site declarations.

7. Maintenance contracts. Portfolio O&M is 30-50% cheaper per site than individual contracts.

Site selection methodology

Multi-site rollouts succeed by careful site selection. Standard methodology:

Phase 1: Estate audit (8-12 weeks)

- Roof area per site (from existing building surveys) - Roof condition assessment (typically Cat 1 desktop review) - Electrical service capacity per site - Building age and structural type - Listed building / conservation area status - DNO region per site

Phase 2: Energy profile analysis (4-8 weeks)

- 12 months of half-hourly consumption per site - Self-consumption potential per site - Refrigeration load (where applicable) - Daytime vs evening load split - Multi-occupier vs single-occupier

Phase 3: Site shortlist scoring (2-4 weeks)

- Roof area threshold (typically minimum 400m² for >50kWp) - Structural compatibility (Cat 1 pass minimum) - Self-consumption above threshold (typically >50% projected) - DNO export capacity adequate - No major conservation constraints - Adequate electrical service capacity

Typical retention from estate to shortlist: 25-45% of sites. The 320-site retail chain case study selected from ~1,200 candidate sites.

Framework tender structure

Effective framework tender for UK commercial solar rollouts:

Tender stages:

1. Prequalification (PQQ): 30+ installer applicants assessed on technical capability, financial standing, sector experience 2. Invitation to Tender (ITT): 8-12 shortlisted installers provided detailed scope 3. Selection (3-4 finalists): Best technical + commercial scoring 4. Framework agreement: Multi-installer or single-installer framework signed

Framework structure options:

- Single-supplier framework: One installer for all sites. Simpler management; concentration risk. - Multi-supplier framework (3-4 installers): Mini-competition per site or call-off. Lower concentration risk; more management overhead. - Regional framework: Different installers for different DNO regions. Geographic specialisation; coordination complexity.

Typical framework duration: 3-5 years with extension options.

Key commercial terms:

- Unit pricing schedule (£/Wp by system size and roof type) - Service levels (response times, delivery commitments) - Workmanship warranty (typically 10 years) - Panel warranty pass-through (typically 25 years) - Liability and insurance terms - Termination clauses and replacement provisions

Programme management

Multi-site rollouts require dedicated programme management:

Core team:

- Programme Director (overall accountability) - Programme Manager (day-to-day delivery) - Technical Lead (engineering design and quality) - Procurement / Commercial Lead (contracts and variations) - Quality Manager (delivery quality and site signoff) - Communications Lead (internal stakeholder engagement)

Standard programme controls:

- Programme master schedule (Gantt across all sites) - Risk register and mitigation plan - Weekly site-level progress reporting - Monthly executive dashboard - Quality assurance per site (commissioning, signoff) - Snagging and defect management - Financial control (commitment, accrual, payment)

Typical programme rates:

- 4-8 sites per week installation rate (small scale) - 8-15 sites per week (medium scale framework) - 15-25 sites per week (large scale rollout)

Resource planning:

- 50-site programme: 2-3 programme management FTE - 200-site programme: 4-6 FTE plus support - 500+ site programme: 8-12 FTE plus regional coordinators

Multi-site finance structures

Common finance structures for UK multi-site commercial solar:

Cash purchase across portfolio:

- Operator deploys £5m+ of capex across estate - 100% Full Expensing tax saving in year 1 (£1.25m on £5m for 25% CT) - Strongest IRR (16-22% over 25 years) - Best for capital-rich PE-backed operators

Asset finance / hire purchase:

- Specialist lenders (Lombard, Aldermore, Praetura, Hampshire Trust, Time Finance) - Treats operator as owner from day one — Full Expensing applies - Typical 5-7 year terms at 7-10% APR - Materially better rates at portfolio scale

Behind-the-meter PPA across portfolio:

- Specialist investor (Atrato, Octopus Energy Generation, BSIF, Greencoat) installs and owns - Operator buys electricity at fixed rate (8-12p/kWh) for 15-25 years - £0 upfront capex preservation - Best for capex-constrained, multi-tenancy operators

Hybrid structures:

- Operator owns sites with strongest self-consumption; PPA for export-heavy sites - Operator owns smaller sites; PPA for larger sites - Common for retail chains and hotel groups

For a 200-site portfolio with mixed site profiles, the optimal structure is often hybrid. Specialist financial advisors (Triple Point, Atrato, Octopus Investments) can structure deals.

FAQs

FAQs on this topic

What's the minimum portfolio size for framework procurement?

10+ sites typically justifies framework procurement. Below 10 sites, individual tendering usually wins on speed and simplicity.

How do I find a suitable solar PPA provider for a portfolio?

Specialist solar finance brokers (Triple Point, Atrato, Octopus Energy Generation) tender PPA quotes across multiple providers. Direct engagement with major providers (BSIF, NextEnergy Capital, Custom Solar) for larger programmes.

Should I appoint a programme manager?

For 20+ site rollouts: yes. Internal facilities teams aren't typically resourced for multi-site solar programme delivery. External programme manager £150-£400 per day.

What's the typical timeline for a 100-site rollout?

12-24 months from kick-off to programme completion. Site selection 3 months; framework procurement 4 months; design + DNO 3 months; installation 6-12 months.