Work out solar inverter sizing instantly with clear inputs, formula shown and shareable results.
Inverters are deliberately undersized relative to the DC array because peak output occurs for only a few hours a year. A DC to AC ratio of 1.15-1.35 maximises energy per unit of inverter cost, accepting 1-3% clipping at midday in exchange for better utilisation and lower capital cost.
Inverter sizing
AC capacity required = DC capacity / DC:AC ratio; units = ceil(AC required / unit rating)
The array only exceeds the inverter rating during a small number of high-irradiance hours. Sizing the inverter for that peak costs far more than the energy clipped.
It depends on the irradiance profile and the tariff. Higher ratios suit diffuse climates and tariffs that reward morning and evening output; lower ratios suit clear desert sites with midday-weighted value.