Start with essentials, not the whole house
A practical backup plan begins with the appliances that must keep running during an outage. List lights, fans, communications and any other essential equipment separately from air conditioning, water heating and cooking loads. Do not assume that a battery can power every circuit.
What size battery backup do I need for my house?
Start with the essential loads you want to keep running during an outage, not the size of the house. For each appliance type, multiply quantity × running power in watts × operating hours, then add the required energy in watt-hours. Account for inverter losses and the battery's permitted usable capacity using verified system specifications. Check inverter continuous power, motor-starting surge and battery current limits separately: enough kWh does not necessarily mean enough kW. Also check whether the system can recharge before the next outage. The worked example below shows the method; it is not a model recommendation or a complete electrical design.
1. Make a load-and-hours worksheet
For each appliance, record quantity, measured running watts and expected operating hours. Estimate energy as watts × hours ÷ 1,000. Add each appliance's energy requirement; use realistic duty cycles for equipment that switches on and off.
Illustrative example — not a product runtime claim
- Lighting: an assumed combined 100 W for 4 hours = 0.40 kWh.
- One fan: an assumed 60 W for 4 hours = 0.24 kWh.
- One router: an assumed 15 W for 4 hours = 0.06 kWh.
Total assumed load: 175 W. Total AC energy: 0.70 kWh. These are example inputs, not appliance specifications or field measurements.
2. Convert load energy into a battery estimate
As an initial estimate: nominal battery energy = required AC energy ÷ assumed conversion efficiency ÷ assumed usable fraction of nominal battery energy.
Using an illustrative 85% conversion efficiency and 80% usable fraction, the example needs 0.70 ÷ 0.85 ÷ 0.80 ≈ 1.03 kWh nominal energy before any additional reserve. Neither percentage is a specification for an Enerup product. Avoid subtracting the same reserve twice.
An installer must account for inverter standby consumption, actual efficiency at the planned load, temperature, ageing and the selected battery's permitted operating limits. A nameplate kWh figure alone is not a guaranteed number of backup hours.
3. Check inverter power and starting loads separately
Battery energy determines a first estimate of runtime; inverter output and battery current limits determine which loads can operate together. Refrigerators, pumps and other motor loads may require much more power at startup than during normal operation.
Do not select an inverter from the energy calculation above. Check continuous output, surge magnitude and duration, power factor, battery current limits and protective devices using exact product documentation.
4. Plan how the battery will recharge
Record the time available between outages, the permitted charge current and whether charging comes from the grid, solar or a supported generator arrangement. A system that cannot recharge sufficiently before the next outage may provide less backup than the first-use estimate.
Choose a product path after sizing
- BL5120 modular battery: review the required module count and approved expansion configuration with the installer.
- BL14336 / BL16076 tower battery: evaluate when a tower-format battery is on the shortlist; check usable energy, handling and inverter fit by exact model.
- Compare batteries and integrated ESS: decide whether a separate battery/inverter or an integrated system suits the installation and service workflow.
No listed product is automatically sized for the example above. Confirm the actual load schedule and model-specific operating limits before ordering.
Prepare your backup-load list
Copy this checklist into your enquiry so we can review the required system size and compatibility. Use measured values or appliance documentation where available; mark unknown values rather than guessing.
| Essential appliance | Quantity | Running power per unit (W) | Actual operating hours during the outage | Starting surge, if applicable |
|---|---|---|---|---|
For cycling appliances such as refrigerators, actual run time may differ from the full outage duration. Avoid counting both an adjusted run time and the same duty-cycle reduction twice. Have the final sizing and installation checked by a qualified installer.
- Country, company and purchasing role:
- Backup duration and typical time available to recharge:
- Existing inverter make/model and battery voltage, if known:
- Available charging source and installation conditions:
- Product quantity and information still to be confirmed:
Prepare a model-specific enquiry
Send your country, company and role, essential loads, backup hours, existing inverter model, installation conditions and expected order quantity. Prices, availability, documentation, delivery and support terms are confirmed for the selected model and order.
Documentation and next steps
Use the product datasheet library for a shortlist, then request the current manual and written confirmation for the exact battery, inverter and firmware combination. This guide does not certify compatibility or compliance.