A 100 kW warehouse solar system suits smaller industrial units, last-mile depots, and self-storage facilities. With 185 panels (at 540W each) covering 600-900 sqm of roof area, the system fits comfortably on most modern 30,000-50,000 sqft warehouse buildings. Per-kW cost is higher than larger systems (project mobilisation costs are amortised over fewer kW) but absolute capex is moderate and payback economics work for owner-occupiers absorbing the 100% AIA tax shield.
Typical 100 kW system specification
Capacity: 100 kW. Panels: 185 modules at 540W (Tier-1 Mono PERC or N-type TOPCon). Roof area: 600-900 sqm usable. Inverters: 2-4 string inverters (50 kW each typical). Annual generation: 92,000 kWh (UK average). Capex: £85-110k installed. AIA tax shield: £21-28k year 1. Payback: 5-7 years simple, 4-6 years after-tax.
When 100 kW is the right size
Buildings 30,000-50,000 sqft with daytime baseload 70-100 kW. Last-mile depots with EV vehicle charging integration. Self-storage facilities (lower baseload, more reliance on SEG export). Small industrial units (engineering, light manufacturing, joinery). Owner-occupied buildings where the £85-110k capex sits within working capital.
Economics worked example
100 kW install on a 35,000 sqft last-mile depot: capex £95k. AIA tax shield year 1: £24k. Annual generation 92,000 kWh. At 75% self-consumption (with EV charging integration: 90%+) and 22p/kWh grid retail: £15-20k/yr saving. SEG export on residual: £1-3k/yr. Total annual benefit £16-23k. Simple payback 4-6 years. After-tax cash payback 3-4.5 years. 25-year IRR 18-22%.
Common questions about 100 kw system
Is 100 kW too small for warehouse solar?
No — 100 kW is a sensible size for smaller industrial units (30,000-50,000 sqft), last-mile depots, and self-storage facilities. Per-kW capex is higher than larger systems (project mobilisation amortised over fewer kW) but absolute capex is moderate and works for owner-occupiers. Below 50 kW, project economics typically don't justify the DNO and design overhead.
What size warehouse fits 100 kW PV?
Buildings 30,000-50,000 sqft with reasonable roof area (600-900 sqm usable) and daytime baseload 70-100 kW. Modern post-2010 buildings with PV-ready profiled steel or membrane roofs. We confirm exact fit during structural survey.
How long does a 100 kW install take?
Total project 6-9 months: desk feasibility (1 week), structural survey (1 day), G99 grid connection (4-8 months — usually rate-limiting at this size), permits (parallel), install and commission (3-5 weeks). Smaller systems typically have faster DNO timescales than multi-MW projects.