Solar Battery Backup Calculator Philippines

Tired of brownouts? List the appliances you want to keep running and how many hours you need backup. The calculator sizes the battery in kWh and amp-hours, suggests an inverter and shows how many solar panels you need to recharge it, with a rough battery cost.

Last updated October 26, 2026. Free, no sign-up, and your numbers stay in your browser.

How to use this calculator

Enter the watts of the appliances you want to keep on during an outage.
Set how many hours of backup you need.
Check the usable share, efficiency, voltage and the battery price per kWh.
Read the battery size in kWh and Ah, the inverter size and the panels needed to recharge.
Add or remove loads to see how the cost changes.

Planning battery backup for Philippine brownouts

Many Filipino homes face brownouts after typhoons or during peak demand. A battery keeps lights, a fridge, fans and the internet running, which also protects food and lets you work from home.

This calculator turns your essential loads and backup hours into a battery size, an inverter size and the solar panels needed to recharge. The numbers help you compare installer quotes and decide whether to back up the whole house or only the essentials.

Size a full system with the solar system size calculator, check the savings with the payback calculator, and see the aircon cost calculator before you add cooling.

How the battery size is worked out

Total load is the sum of the watts you want to keep running.
Energy needed equals the total watts times the backup hours, divided by 1000 to get kWh.
Battery size is that energy divided by the usable share of the battery and by the efficiency of the inverter and battery.
Amp-hours equal the battery kWh times 1000 divided by the system voltage. The inverter gets a 25 percent margin, and the solar size is what recharges the energy in one sunny day.

Tips to save more

Back up essentials first. Fridge, lights, fans and Wi-Fi need little power.
Ask for the battery warranty in years and cycles.
Check that the inverter can handle the starting power of motors.
Keep a small power bank for phones and radios as a second layer.

Frequently asked questions

What size battery do I need for a blackout?

Add up the watts of the appliances you want to run, multiply by the hours of backup and divide by 1000 to get kWh, then allow for usable capacity and losses. The calculator does it for you.

Can a battery run an aircon?

It can, but an aircon draws far more power than lights and fans, so the battery and inverter must be much larger and cost more. Start with essentials.

What is depth of discharge?

It is the share of a battery you can use without shortening its life. Lithium batteries often allow around 80 to 100 percent, while lead-acid batteries allow much less.

Do I need solar panels with a battery?

Not to run the battery in an outage, but panels recharge it for free during the day, especially with long or frequent outages.

Are these prices current?

They are examples. Battery prices vary by brand and chemistry, so ask installers for written quotes with warranty details.

Helpful guides and deals

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Solar System Size Calculator Philippines How many solar panels and kW your home needs Solar Panel Payback Calculator Philippines Estimated savings and payback period for home solar Electricity Bill Calculator Appliance cost per month and your biggest power hogs

This calculator gives estimates for planning only. It is not financial, tax or legal advice. Confirm exact figures with your employer, bank, lender or the relevant government agency.