Side-by-side comparison
Comparison: typical UK office solar O&M routes.
| Factor | Outsourced O&M | In-house O&M |
|---|---|---|
| Annual cost per kWp | £12-25/kWp/year | £6-12/kWp/year (>2MW scale) |
| Reactive fault response | Within 5 working days (contracted) | Variable; depends on team workload |
| Specialist expertise | Solar-specialist contractors | General electrical / facilities |
| Inverter replacement (year 12-15) | Often included in Tier-4 contract | Specialist sub-contracted |
| Performance monitoring | Continuous cloud-platform | Building BMS only (often) |
| G99 grid liaison | Direct relationship with DNO | Via O&M contractor where needed |
| Performance guarantee | Available (Tier-4) | Not available |
| Typical availability | 99%+ | 95-97% |
| Best for system size | Single building / portfolio <2MW | Portfolio >2MW with sufficient scale |
| Best for organisation type | Tenant or single-occupier | Large landlord, public sector estate |
| Cost basis | Fixed per-kWp annual | Amortised across portfolio + team |
The decision
Pick on the basis of your specific situation:
Outsourced O&M
Best for: Most UK office solar customers — single building, small portfolio, no in-house solar specialist. Performance guarantee available; uptime materially higher.
In-house O&M
Best for: Large landlord portfolios above 2 MWp total capacity with existing in-house facilities team. Per-kWp cost drops below outsourced once scale and team expertise are present.
How we model it for you
For every office solar proposal, we model the relevant comparison options side-by-side. Send us your half-hourly meter data and roof plan via the quote form, and we'll return a fixed-price proposal within 7 working days with all relevant routes compared in your specific situation.