Ilaw, Wi-Fi at Ref: How Much Battery Backup Does Your Family Need?

Choose one outage scenario to design around

Start with a specific event, such as an eight-hour evening interruption. Write down who will be home, which rooms will be occupied and which appliances matter. Then consider a second, more demanding case, such as a cloudy day followed by an overnight outage.

This keeps the conversation focused. You might decide that bedroom fans, the refrigerator, lights and internet are essential, while laundry and electric cooking can wait. Another family may prioritise a water pump. Neither list is universal; the designer needs your actual priorities, including equipment whose interruption would create a serious problem.

Build an appliance energy worksheet

For an appliance with a steady load, multiply watts by operating hours, then divide by 1,000 to obtain kWh. Appliances with compressors or variable-speed motors need measured or suitably modeled energy, because their nameplate power does not tell you how long they operate at that level.

The following is a hypothetical eight-hour planning example dated 20 September 2026. It is not a product specification or a runtime promise. Replace every value with measurements or a defensible estimate for your equipment.

• Four 10-watt lights for five hours: 0.20 kWh.
• One 15-watt router for eight hours: 0.12 kWh.
• One 50-watt fan for eight hours: 0.40 kWh.
• A refrigerator assumed to use 0.60 kWh across the outage: 0.60 kWh.
• Total energy delivered to these appliances: 1.32 kWh.

Translate appliance energy into an installed design

The worksheet total is energy at the appliances. The battery must also accommodate conversion losses, the chosen reserve, available starting charge and any energy consumed by the system itself. Battery age and operating conditions can change the energy available over time.

Ask the supplier to show each allowance rather than adding an unexplained safety percentage. A nominal battery capacity, a manufacturer's usable capacity and the energy accessible above your chosen reserve are different figures. Once those are clear, you can compare two proposals without assuming that an identical number on the front of the battery means identical delivered backup.

Check the moment when appliances start together

Energy is only half the design. A refrigerator or pump can require extra power when starting, while other appliances may already be operating. The designer should verify continuous output and starting capability for the actual combination, including the limits of both battery and inverter.

In our worksheet, the lights, router and fan total only 105 watts while operating together. That does not establish the full system's peak demand: we have not included the refrigerator's starting behaviour. This is why adding up daily kWh cannot, by itself, tell you which inverter will reliably run the essential circuits.

Agree how much charge is kept for emergencies

A battery used heavily for evening consumption may have less energy available when an unexpected outage starts. A higher emergency reserve can leave more stored energy for backup, while changing how much is routinely available for other uses. Discuss that tradeoff using your household priorities.

Ask to see the proposed operating settings and what your family is allowed to change. Also ask what happens if the battery reaches its minimum charge during an outage. An attractive runtime calculated from a full battery should be accompanied by a scenario beginning at the reserve or another realistic starting state.

Model recharge as well as discharge

Storage shifts energy in time; it does not create it, and conversion is not perfectly efficient. ^[1] For a prolonged outage, your plan also needs a realistic source of recharge. Confirm whether the installed solar system can charge the battery while separated from the grid.

Ask the designer to assess a sequence of cloudy days, not just a sunny afternoon. In some households, reducing optional loads during a long interruption is a practical part of the plan. Write that plan down so everyone knows which appliances can be paused and which should continue, rather than improvising when the battery indicator falls.

Compare the whole backup offer

Request a proposal listing supported circuits, continuous output, starting-load checks, usable energy, reserve assumptions and expected runtime for the agreed scenario. Include the installation location, monitoring access, warranty conditions and service responsibility. A battery must be configured for backup to provide it; storage alone is not the complete promise. ^[2]

Take your worksheet to Lightning Energy Philippines and ask which assumptions need measurement. A clear design may start with a modest set of essentials and allow a larger option for comfort loads. Ilaw, Wi-Fi at ref becomes a useful brief when the appliances, hours and limits are all visible.