String inverters vs central inverters
String inverters (SolarEdge, Huawei, SMA, Fronius): 50-100 kW per unit. Distributed across roof. Lower per-unit cost. Easier to replace at end-of-life (typically year 12-15). Better for systems with shading or multiple roof orientations. String inverters dominate UK commercial solar below 3 MW. Central inverters: 200 kW – 1.25 MW per unit. Single ground-mounted enclosure. Higher per-unit cost. Longer replacement cycle (20+ years). Better for very large clean-roof installs above 3 MW.
Module-level optimisers (SolarEdge)
Optimisers attached to each panel performing per-panel MPPT. Reduces shading mismatch losses. Slightly higher capex (5-10%). Optimisers warranted 25 years matching panel life. Inverter unit (without optimiser) replaceable at year 12-15. Strongly recommended where roof has any shading or orientation complexity.
Inverter sizing relative to panel capacity
Industry-standard DC:AC ratio is 1.1-1.3 (panels 10-30% over-sized vs inverter rating). Reflects that panels rarely deliver nameplate capacity simultaneously. Higher ratio (1.25-1.30) for shading-prone or off-orientation roofs. Lower ratio (1.05-1.15) for clean south-facing roofs.
Common questions
Which inverter brand is best for UK warehouse solar?
No single best — depends on project. SolarEdge for shading-prone roofs (module-level optimisers). Huawei FusionSolar for cost-efficient clean roofs. SMA Sunny Tripower for established commercial track record. We are manufacturer-independent.
How often do solar inverters need replacing?
String inverters: typically year 12-15. Module-level optimisers: year 25 matching panel life. Central inverters: year 20+. Replacement cost typically £80-150/kW including labour.