Critical load planning for home battery installers begins with a service agreement: which functions must continue during an outage, for how long, and under what operating restrictions? Convert those answers into a circuit-level load schedule before comparing battery capacities.
This approach gives distributors and installers a clearer basis for a proposal. A request to “back up the house” leaves too much unresolved about heating, cooking, water supply and simultaneous appliance use.
Confirm what the system can support during an outage
Do not assume a solar-and-battery installation automatically supplies every circuit when the grid fails. The Australian Government’s battery guidance explains that backup depends on configuration, may cover selected circuits, and can require users to manage demand.
Ask the system designer to identify the backup architecture and the loads it can actually energize. PNNL describes critical-load subpanels as one way of separating selected loads. That is an architecture example; the appropriate arrangement depends on the equipment and local installation requirements.
Prioritize services with the customer
Start with the consequence of losing a service. Refrigeration, communications, lighting and water supply may have different priorities at different properties. A router also needs any associated modem or network equipment to remain powered. A lighting circuit may contain more fittings than the customer expects.
Record three groups: required throughout the outage, permitted only at agreed times, and excluded from backup. Ask who will operate any manual restrictions. Where continuous service is essential, document the allowed interruption and arrange specialist design review rather than assuming ordinary battery backup meets it.
Turn the priorities into a load schedule
| Field | Information to capture | Reason |
|---|---|---|
| Service and circuit | Device list and verified circuit reference | Makes the backup scope inspectable |
| Running demand | Measured or documented input power | Supports the energy estimate |
| Startup behavior | Starting demand and duration where relevant | Supports the power review |
| Operating pattern | Hours, cycling and time window | Avoids treating every appliance as constant |
| Priority | Required, scheduled or excluded | Defines operating decisions |
| Control | Automatic, manual or no control | Identifies who enforces the plan |
Mark estimated values clearly and assign a person to replace them with evidence. A monthly electricity bill provides context, but it does not show which backed-up loads run together during an outage.
Calculate energy for a stated scenario
For an illustrative eight-hour outage, assume communications use 30 W continuously, selected lighting uses 60 W for five hours, and a refrigerator averages 50 W over the eight hours. Their load-side energy totals 0.24 + 0.30 + 0.40 = 0.94 kWh.
These are invented planning assumptions, not measured appliance data or an evjrich runtime claim. Refrigerator cycling can change with conditions. The figure excludes conversion losses, system consumption, reserve and other loads. The designer must translate the agreed load-side requirement into a battery specification using verified equipment data and operating limits.
Then review simultaneous running demand and motor starts separately. A schedule with modest total energy can still demand more instantaneous power than the selected system can supply.
Test the operating promise before handover
Evaluate a clearly defined outage scenario, including a starting battery condition and an assumption about solar recharge. A conservative no-recharge scenario can expose dependencies that a sunny-day demonstration would hide. If the proposal depends on solar restarting after depletion, obtain model-specific confirmation of that function.
Agree how scheduled loads will be restricted and explain those restrictions at handover. The acceptance record should identify the included circuits, excluded services and evidence supporting the agreed operation. Use an approved installer test procedure rather than improvising an outage test.
Review Applications for residential solar storage projects and the Products overview for battery formats after defining the load schedule. To discuss a distribution or installation programme, send the circuit priorities, outage assumptions and inverter details when you discuss your requirements via B2B enquiry.