Start with kWh, not panel count
Solar sizing begins with your electric bill. Look for monthly kilowatt-hour consumption, usually shown as kWh. Peso amount matters too, but kWh tells you how much energy your home actually uses.
A home using 300 kWh per month and a home using 900 kWh per month need very different solar designs, even if both want lower bills. If possible, review 12 months of bills because air conditioning, holidays, school schedules, and rainy-season habits can change usage.
A good proposal should explain expected production in kWh, not only the number of panels or the peak wattage printed on the panel datasheet.
Photo: Pexels / Los Muertos CrewA practical sizing workflow
1. Gather bills
Use monthly kWh to understand your normal and peak consumption.
2. Map daytime use
List loads running from morning to afternoon, especially aircon, pumps, refrigeration, and work equipment.
3. Check roof limits
Account for shade, direction, slope, usable area, roof condition, and safe access.
4. Match the system type
Choose grid-tied, hybrid, or off-grid sizing based on savings, backup, and utility goals.
Example size ranges
These examples are planning ranges, not final engineering recommendations. Real output changes with panel wattage, inverter behavior, roof orientation, shading, utility requirements, and local weather.
| Monthly usage | Common household profile | Planning direction |
|---|---|---|
| 200 to 350 kWh | Small home, light aircon use, basic appliances | Often starts with a modest grid-tied system focused on daytime essentials. |
| 350 to 700 kWh | Family home with regular aircon, refrigerator, laundry, and work-from-home loads | Usually benefits from a medium rooftop system with careful daytime-use matching. |
| 700 to 1,200+ kWh | Larger home, multiple aircon units, pumps, pool, or high daytime demand | May justify a larger system, but roof capacity and export rules become more important. |
Why daytime usage matters so much
Solar panels produce power during the day. If your home uses that electricity instantly, you avoid buying that energy from the grid at the retail rate. This is called self-consumption.
If your system produces more than the home is using, the extra power may be exported if your net-metering arrangement is approved. Export credits can help, but a Philippine solar design should not assume every unused kWh has the same value as one kWh consumed inside the home.
Shift loads when it makes sense
Running laundry, water pumping, charging, and some cooling during sunny hours can improve solar value. The goal is not inconvenience; it is using more of your own clean power when it is available.
Photo: Pexels / Kindel MediaRoof and equipment checks
A system that looks good on paper can underperform if the roof is shaded, faces a poor direction, has limited usable space, or needs structural work. This is why site assessment matters before final sizing.
Roof area
Usable roof area excludes pathways, unsafe edges, vents, water tanks, shadows, and sections that cannot carry the mounting system properly.
Panel wattage
Higher-wattage panels can reduce panel count, but the final design still depends on array layout, inverter limits, and roof geometry.
Inverter size
The inverter should match the array, grid connection, export plan, and whether you need hybrid or backup features.
Electrical readiness
Main breaker, service entrance, grounding, and panel board condition can affect installation scope and permitting.
If you need batteries, size backup loads separately
Battery sizing is not the same as solar panel sizing. A battery-backed system should start with a list of appliances that must run during outages and the number of hours you want them supported.
For many Philippine homes, a practical backup plan covers essentials first: lights, Wi-Fi, phone charging, refrigerator, fans, CCTV, gate motor, and selected outlets. Air conditioning backup is possible, but it requires a much larger battery and inverter plan.
Solar sizing FAQ for Philippine homeowners
How many solar panels does a Philippine home need?
It depends on monthly kWh usage, roof space, panel wattage, shading, orientation, and how much daytime consumption the home has. Start with the electric bill's monthly kWh, then size the system around useful production rather than panel count alone.
Should I size solar to cover 100 percent of my bill?
Not always. In the Philippines, self-consumed solar is usually more valuable than exported solar, so the right size often balances daytime loads, net-metering expectations, budget, and roof conditions.
Do batteries change solar system sizing?
Yes. Battery-backed systems should be sized around backup loads and hours of autonomy, not only monthly bill savings.
Can I add more panels later?
Often yes, but it is easier when the original inverter, roof layout, conduit path, and permits leave room for expansion. Tell your installer early if future expansion matters.
Want a size estimate from your actual bill?
SolarHome.ph can review your kWh history, roof space, daytime load pattern, and backup needs so your system size is based on real Philippine home conditions.
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