Business generator

• Sizing

  Sum of loads ×1.5 reserve + compressor starting currents ×3; 10–20 kW typical retail.

• Fuel type

  Diesel — reliability/hours, petrol — cheaper/mobile, gas — cheap fuel for stationary units.

• ATS

  Automatic transfer switch: generator starts in 10–15s — mandatory for tills, fridges, servers.

• Legal

  DSO backup-connection contract, site passport, inspection; rooftop/street generators — noise and exhaust rules.

A generator without ATS is a 'manual switch': the fridge defrosts during startup. For business: diesel + ATS + a dedicated critical-load line, everything else on schedule.