How to Size a PV Generator for an Off-Grid Site: A Practical Checklist

      Sizing a PV Generator for an off-grid or weak-grid site is less about picking the biggest cabinet and more about matching the conversion chain to your actual load. This checklist walks through the five inputs every configuration should start from, using the Solar 3B3 family as a worked example.

      1) Load profile. List the continuous and peak loads in kW, and how many hours each runs per day. A PV Generator's output power factor is 0.8 — so size the cabinet's kVA to your peak kW divided by 0.8 — and it delivers 380/400/415 V ±1% at 50/60 Hz. Its input power factor is 0.97 (with an optional filter). Peak load sets the cabinet size; continuous load sets the PV and battery.

      2) Solar resource. Match recommended PV input to the cabinet. The Solar 3B3 family's recommended PV input runs from 14.56 kW on the 10K up to 72.8 kW on the 60K, with a 498 V maximum and 416 V rated DC voltage — enough range to right-size the array without oversizing the inverter. Oversizing the PV string beyond the rated voltage only adds cost, not output.

      3) Storage autonomy. Decide how many sun-free hours the battery must cover. LFP packs at a 409.6 VDC pack voltage with 100 Ah capacity (configured as required) and a 6000-cycle design life (measured at the cell level) let you budget replacement cost years ahead; BMS-managed charging runs at 0.5 C maximum charge current and 1 C rated discharge current (a 100 Ah pack accepts up to about 50 A for charging — roughly a 2-hour full charge — and delivers 100 A continuously). Autonomy, not capacity headline, is what keeps the lights on overnight.

      4) Transfer and redundancy. If the load cannot tolerate an interruption, the 0 ms static-switch transfer between PV, battery, mains and generator is the figure to design around. Up to six units can be paralleled for N+1 redundancy when uptime is critical — and the same communication bus (RS485, RS232, dry contact and SNMP card — both optional) links them all.

      5) Site envelope. Confirm operating temperature (0–40 °C), altitude (up to 1500 m), noise (below 58 dB) and humidity (0–95% non-condensing). These decide where the cabinet can physically live on site, and whether it needs a shaded or ventilated enclosure.

      No two sites share the same load and sun, which is why a generic answer rarely fits. If you share your load profile and solar resource, we can help you turn this checklist into a configuration — and point out where a generator still earns its keep.