Load division: choosing which appliances run on solar backup

What you will see

• Essential appliances lose power during outages.
• Overload trips keep returning.
• Backup time has dropped since new appliances were added.
• New ACs, pumps or machinery are planned.

Why it happens

Backup load is the group of appliances and circuits selected to receive power during a grid outage. They must be connected through the system’s approved backup arrangement, and their demand must stay within its power and energy limits.

While the grid is available, these appliances may use solar, battery or grid electricity according to the operating mode. “Backup” describes their supply arrangement; it does not mean they run only from the battery. Non-backup appliances still benefit from solar while the grid is on; they lose supply during an outage.

Division follows circuits, not room names. A room’s lights, sockets and AC may be on different circuits, so moving an appliance to another socket does not guarantee it is on backup. The electrician identifies the existing circuits and separates them where needed, following the exact inverter’s installation manual.

A three-phase inverter has limits for its total output and for each phase. Too much demand on one phase can cause an overload even when the total looks acceptable, so single-phase appliances must be spread across the phases within that model’s limits.

Sizing depends on which appliances run together and their starting demand, the inverter’s backup rating, the battery’s permitted discharge power and how long backup must last. Adding battery capacity may extend runtime, but it does not raise the inverter’s output limit.

Cable sizes, protective devices, neutral and earthing arrangements, earth-leakage protection and any changeover must follow the manufacturer’s design and local requirements. Backup must never feed the public grid during an outage. A qualified electrician should complete, test and label the wiring.

Diagram

Two boards, two jobs

Backup board

Fed from the inverter’s backup output. Stays on during load-shedding while power and energy last.

Selected lightsFansWi-Fi routerCCTVRefrigerator, if its start-up is supported

Main board

Grid-connected side. Uses solar while the grid is on, off during load-shedding.

Water heaterOvenExtra ACsWater pumpMachinery

Three-phase: same total, different result

Uneven

Per-phase limit

L1L2L3

L1 overloads even though the total looks acceptable.

Balanced

Per-phase limit

L1L2L3

Each phase stays within its limit.

What you can check yourself

• List the appliances you want on backup and when they usually run together.
• Note which appliances lose power during outages and which stay on.
• Check whether the backup circuits are clearly labelled on the board, without opening it.
• Note any heavy appliance added since the system was installed.

What not to do

• Do not open boards or move circuit wiring yourself. Backup circuits can stay live during load-shedding.
• Do not join backup and grid circuits with an improvised connection.
• Do not move heavy appliances onto backup sockets without checking with us.

When to call us

• Essential appliances lose power during outages.
• Overloads recur, or backup time has dropped.
• You are adding ACs, pumps or machinery.

Load division for homes and factories in Faisalabad and Lahore

Load division should be part of every hybrid design, whether the inverter is Solis, GoodWe, Growatt or Huawei. For Faisalabad textile units, Lahore offices and larger homes across Punjab on three-phase supply, how the load is spread across phases matters as much as the total system size.

Send us

Your inverter and battery models, the appliances you want on backup, their usual operating hours, and your city and area.