Quick answer: To size a solar system for brownouts in the Philippines, you need three numbers: the wattage of the appliances you must keep running (inverter size), the energy they use during a typical outage (battery capacity in kWh), and enough solar panel capacity to recharge that battery in one day. A typical home running a refrigerator, fans, lights and Wi-Fi needs a 3.6kW inverter and a 5kWh battery.
Key takeaways
- A solar system for brownouts is sized by three numbers: peak watts (inverter), outage energy in kWh (battery) and daily recharge (panels).
- The battery is the biggest decision. Divide the energy your appliances use during an outage by 0.8 to get the battery size you need.
- Size your solar panels for the rainy season, not for sunny March and April.
- Match battery voltage to inverter voltage, and have a licensed electrician do the final installation.
Who this guide is for: homeowners, small offices and stores on Meralco or electric-cooperative grids who want power to stay on during brownouts. Who it is not for: anyone sizing a system purely to export power under net metering, which is a different calculation.
What determines the size of a solar backup system?
The size of a solar backup system is determined by how much power your appliances draw at the same time, how much energy they use during an outage, and how quickly your panels can recharge the battery afterwards. Each of these maps to one component.
- Inverter (kW): must handle the combined running watts and startup surge of everything on at once.
- Battery (kWh): must store enough energy to run those appliances for the length of the brownout.
- Solar panels (kWp): must produce enough energy in one day to refill the battery and run daytime loads.
A hybrid inverter is a single unit that manages solar panels, a battery and the grid, switching to battery power when the grid fails. It is the core of most brownout backup systems in the Philippines.
Step 1: Which appliances do you need to run during a brownout?
Start by listing only the appliances you truly need during a brownout. Backing up essentials such as the refrigerator, fans, lights and Wi-Fi costs far less than backing up the whole house, because high-wattage appliances like aircons, water heaters and electric ovens drive battery size up quickly.
Use the table below as a starting point, then check the wattage label on your own appliances. Figures are typical ranges for Philippine households.
| Appliance | Typical running watts | Startup surge | Typical use during an 8-hour brownout |
|---|---|---|---|
| LED bulb | 7–12W | None | 4–6 hours |
| Electric fan | 40–75W | Low | 8 hours |
| Refrigerator (inverter type) | 80–150W while the compressor runs | Medium | Cycles on and off, about half the time |
| Wi-Fi router / modem | 10–20W | None | 8 hours |
| LED TV (32–55 inch) | 50–120W | None | 3–4 hours |
| Laptop and phone charging | 45–65W | None | 3–4 hours |
| Rice cooker | 500–700W | None | Under 1 hour |
| Water pump (0.5–1 HP) | 370–750W | High, often 2–3× running watts | Short bursts |
| 1 HP inverter split aircon | 700–1,000W | Medium | 3–6 hours |
For each appliance, multiply watts by hours of use to get watt-hours (Wh), then add them together. Divide by 1,000 to convert to kilowatt-hours (kWh). This total is your outage energy.
Step 2: How big should your inverter be?
Your inverter must be larger than the total running watts of everything switched on at once, with headroom for startup surges from motors and compressors. A good rule is to add up running watts, then choose an inverter at least 1.5 times that figure if you have a refrigerator, pump or aircon on the circuit.
| Hybrid inverter size | Battery voltage | Suits |
|---|---|---|
| 1.2kW hybrid inverter | 12V | Lights, fans, Wi-Fi and phone charging |
| 3.6kW hybrid inverter | 24V | A typical home: fridge, fans, lights, TV, Wi-Fi |
| 6.2kW hybrid inverter with Wi-Fi | 48V | Larger homes, or essentials plus one aircon |
| 12kW hybrid inverter with Wi-Fi | 48V | Whole-home backup, small offices and stores |
Battery voltage must match the inverter. A 12V inverter pairs with 12V batteries, and a 48V inverter pairs with 51.2V (48V-class) batteries. Browse all solar hybrid inverters to compare MPPT ranges.
Step 3: How much battery capacity do you need?
To find the battery capacity you need for a brownout, divide your outage energy by 0.8. The 0.8 factor covers inverter losses and the reserve you should leave in the battery so it is never fully drained.
Battery size (kWh) = outage energy (kWh) ÷ 0.8
Example: if your essentials use 2.6kWh during an 8-hour brownout, you need 2.6 ÷ 0.8 = 3.25kWh of battery. The next standard size up is a 5kWh or 5.12kWh battery, which also leaves room for longer outages.
| Outage energy | Battery needed | Matching Cybotix battery (48V-class) |
|---|---|---|
| Up to 4kWh | Up to 5kWh | 5.12kWh / 51.2V / 100Ah |
| 4–8kWh | 5–10kWh | 10.24kWh / 51.2V / 200Ah |
| 8–12.5kWh | 10–16kWh | 16kWh / 51.2V / 314Ah |
| 12.5–24kWh | 16–30kWh | 30.7kWh / 51.2V / 600Ah |
For small 12V systems, the 1.28kWh and 2.4kWh 12V lithium batteries pair with the 1.2kW inverter. See the full range of solar lithium batteries.
Step 4: How many solar panels do you need to recharge the battery?
You need enough panel capacity to refill the battery in a single day, even in cloudy weather. For planning in the Philippines, a conservative figure is that each 1kW of solar panels produces about 3.5kWh per day during the rainy season. Sunnier months produce more, but sizing for the wet season keeps your backup reliable from June to November.
Panel capacity (kWp) = battery energy to recharge (kWh) ÷ 3.5
Example: to recharge 5kWh in a day, you need about 5 ÷ 3.5 = 1.4kWp of panels. That is three 590W TOPCon solar panels (1.77kWp), with some capacity left over for daytime appliances.
If you also want solar to run appliances during the day, not just recharge the battery, add panel capacity for those loads. Actual output varies by province, roof direction and shading. You can check estimated solar output for your exact location with the free Global Solar Atlas.
Worked examples: three Philippine setups
The examples below use the formulas above with typical appliance figures. Your own numbers will differ, so treat them as starting points.
| Basic home | Home with aircon | Small office or store | |
|---|---|---|---|
| Backed-up loads | Fridge, 3 fans, 6 LED lights, Wi-Fi, laptop | Basic home + TV + 1 HP inverter aircon for 4 hours | 2 × 1.5 HP inverter aircons, 4 computers, freezer, lights, Wi-Fi |
| Brownout length | 8 hours | 8 hours | 8 hours (business hours) |
| Outage energy | About 2.6kWh | About 6.1kWh | About 18.5kWh |
| Battery needed (÷ 0.8) | About 3.3kWh | About 7.7kWh | About 23kWh |
| Peak running load | About 0.5kW | About 1.4kW | About 3kW |
| Panels to recharge (÷ 3.5) | About 1kWp: 2 × 590W | About 2.2kWp: 4 × 590W | About 6.6kWp: 10 × 720W |
| Matching Cybotix setup | 3.6kW all-in-one with 5kWh battery | 5kW all-in-one with 8kWh battery | 12kW all-in-one with 32kWh battery, or a 12kW hybrid inverter with a 30.7kWh battery |
In the small office example, the panel figure only covers recharging the battery. If the aircons also run on solar during sunny hours, plan for a larger array, which the 12kW inverter’s two MPPT inputs are built to handle.
Separate components or an all-in-one system: which is better?
An all-in-one system combines the hybrid inverter and lithium battery in one cabinet, so it is quicker to install and avoids voltage-matching mistakes. Separate components give you more freedom to choose sizes and add batteries later.
- Choose all-in-one if you want a tidy, ready-matched setup for a home or small business. Cybotix offers all-in-one inverter and battery systems from 3.6kW/5kWh up to 12kW/32kWh.
- Choose separate components if you need an unusual battery size, already own part of a system, or expect to expand storage in stages.
Does a solar system keep working during a brownout?
A solar system keeps your power on during a brownout only if it has a battery and a hybrid or off-grid inverter. Standard grid-tied systems without a battery are designed to shut down when the grid fails, so your panels stop supplying the house even in full sun.
With a hybrid inverter and battery, essential circuits run from the battery when the grid drops, and the panels recharge it during the day. This is also the only way to keep power on during night-time brownouts, when panels produce nothing.
What Philippine conditions affect your system size?
- Rainy season: cloud cover from June to November reduces daily solar output, which is why this guide sizes panels conservatively.
- Heat: solar panels produce slightly less power when very hot. Lithium batteries and inverters also last longer in a shaded, ventilated spot away from direct sun.
- Typhoons: panel mounting must be rated for strong winds and fixed into the roof structure, not just the roofing sheets.
- Long provincial outages: if brownouts in your area regularly last a full day, size the battery for the longest typical outage, not the average.
- Island and off-grid sites: with no grid to fall back on, add a margin of 20–30% to both battery and panels.
Do you need net metering for brownout backup?
No. Net metering is not required for a brownout backup system. Net metering lets you export surplus solar power to your distribution utility for bill credits under the Renewable Energy Act of 2008 (Republic Act No. 9513) and the rules of the Energy Regulatory Commission. A brownout backup system can run without exporting anything. If you later want to apply, contact your utility, since application steps are handled by Meralco or your electric cooperative.
Installation and safety
Have a licensed electrician install your system. Cybotix Philippines is a solar distributor, not an installation contractor, and correct wiring, breakers and earthing are essential for safety and for your warranty.
- Use correctly rated solar cable and connectors, such as our 6mm PV cable with MC4 connectors.
- Ask your installer to configure panel strings within your inverter’s MPPT voltage range.
- Keep batteries indoors or under cover, away from direct sun and rain.
- Label which circuits are on backup so your household knows what will stay on during a brownout.
Frequently asked questions
How many kWh battery do I need for an 8-hour brownout?
Most Philippine homes running a refrigerator, fans, LED lights and Wi-Fi for an 8-hour brownout use about 2.5–3kWh, so they need a 5kWh battery. Adding an inverter aircon for a few hours raises the need to about 8–10kWh.
Can a solar system run an aircon during a brownout?
Yes, a solar system can run an inverter aircon during a brownout if the inverter and battery are sized for it. A 1 HP inverter aircon running 4 hours uses roughly 3–4kWh, so pair it with at least a 5kW inverter and an 8kWh battery alongside your other essentials.
Is a 3.6kW inverter enough for a house in the Philippines?
A 3.6kW inverter is enough for most Philippine homes backing up essentials: refrigerator, fans, lights, TV and Wi-Fi. It is not enough for whole-home backup with several aircons, which typically needs a 6kW to 12kW inverter.
How many solar panels do I need for a 10kWh battery?
To recharge a 10kWh battery in one day during the Philippine rainy season, you need about 3kWp of solar panels. That is five 640W TOPCon panels or four 720W panels, plus extra capacity if solar also runs daytime appliances.
Will my solar panels work during a brownout without a battery?
Standard grid-tied solar systems without a battery shut down during a brownout for safety, so they do not power your home. To keep power on during brownouts, you need a hybrid inverter with battery storage.
Can I add more batteries to my solar system later?
With separate components, you can usually add battery capacity later as long as the new battery matches the inverter’s voltage. Ask Cybotix Philippines to confirm compatibility before buying, since mixing battery models can affect performance.
How long does delivery take within the Philippines?
Cybotix Philippines ships in-stock items from local Philippine stock, usually within 24 hours of order confirmation, with delivery nationwide including Visayas, Mindanao and island provinces. Every unit carries a 2-year local warranty.
Get a free brownout backup sizing
Not sure which setup fits your home or business? Send your appliance list, location and typical brownout length to our Philippine team through the Contact Us page. We will recommend the inverter, battery and panel combination that fits before you spend anything.