Building Type Specialist
Solar panels for modular and prefabricated offices
Specialist solar PV installation considerations for modular office buildings.
Why modular office buildings need a specialist approach
Modular office buildings (Portakabin Solus, Algeco, McAvoy, Wernick) are increasingly used as permanent office accommodation, particularly in education, healthcare admin, and government estate. Roof structures are typically lighter than traditional buildings (8-15 kg/sqm capacity vs 30+ kg/sqm).
Technical detail
Lightweight PV systems (250-300W mono-PERC modules with lightweight clip-fix mounting) typically deliver 8-12 kg/sqm installed load — within modular building structural capacity. System sizes typically smaller than traditional offices: 20-150 kWp range.
What we deliver
For every modular office buildings project we structure a complete service: free half-hourly meter data feasibility study including structural loading assessment to BS EN 1991, fixed-price proposal, planning route confirmation, DNO G99 application, MCS-certified install with appropriate mounting system for the building type, commissioning to IEC 62446, and a Scope 2 Disclosure Pack for ESG reporting.
Structural capacity of modular buildings
Modular office buildings (Portakabin Solus, Algeco, McAvoy, Wernick) typically have lighter roof structures than traditional buildings — 8-15 kg/sqm capacity vs 30-60 kg/sqm. Modular manufacturers publish per-module structural loading tables; verify against PV system weight at proposal stage.
Lightweight PV mounting options:
- Lightweight ballasted (10-12 kg/sqm). Reduced ballast tubs with recycled-plastic weights instead of concrete. Limits panel tilt to 5-10° (lower yield) but stays within modular structural envelope.
- Direct-fix to module roof. Mechanical fix through module roof skin to the steel frame within. Requires manufacturer approval and warranty endorsement. Best done in collaboration with the modular OEM at module specification stage.
- Standalone canopy structure. Independent steel canopy spanning between modular buildings or over parking. Loading on canopy not modules. Higher capex but maximises generation.
Modular office solar — typical project sizing
Modular offices are typically smaller than traditional builds — single-storey, 200-2,000 sqm footprint. PV sizing:
- Small managed office (300 sqm): 20-40 kWp typical
- Mid-size modular (1,000 sqm): 60-120 kWp typical
- Large modular complex (2,000+ sqm): 120-300 kWp typical
System cost per kWp on modular tends to run slightly higher than traditional builds (£1,000-£1,400/kWp vs £700-£1,000/kWp) due to smaller scale and lightweight mounting requirements.
Where modular offices are used in 2026
Modular construction has matured significantly since 2015. Common deployment scenarios:
- Education estate temporary classrooms (often becoming permanent through extended planning consents)
- NHS administrative buildings on hospital sites
- Construction site offices (typically 2-5 year deployments)
- Local government estate — neighbourhood offices, satellite admin buildings
- Mining / energy / quarry site offices
- Emergency response infrastructure (DEFRA, Environment Agency, Cobra centres)
Relocation and removability
Modular buildings can be relocated. PV systems on modular need to be relocatable to match — particularly on construction-site offices and temporary deployments. Lightweight ballasted systems can be dismounted, transported, and re-installed in 1-2 days. Direct-fix systems are more involved (re-roof penetration sealing during dismount, structural reattach at new location).
Relocation cost typically 15-25% of original install. Cash-positive over 2-3 year deployments at most UK commercial electricity tariffs.
Modular OEM partnerships
For new modular buildings being procured, working with the OEM at specification stage to integrate PV-ready mounting points and cable routing is cheaper than retrofit. Most major UK modular manufacturers offer PV-ready specifications as a paid upgrade.
Modular insurance considerations
Modular building insurance often has specific provisions for roof additions. Confirm policy extension at design stage; some insurers require structural certification beyond standard PV documentation.