Here's the simple formula Filipino solar installers use:
The Bill-to-kW Formula
Your monthly bill ÷ ₱1,500 = recommended system size in kW
Monthly Meralco Bill | System Size | Panels Needed | Estimated Cost |
|---|---|---|---|
₱3,000 | 2 kW | ~4 panels | ₱120,000 - ₱160,000 |
₱5,000 | 3 kW | ~6 panels | ₱180,000 - ₱230,000 |
₱8,000 | 5 kW | ~10 panels | ₱280,000 - ₱350,000 |
₱12,000 | 8 kW | ~16 panels | ₱400,000 - ₱500,000 |
₱15,000 | 10 kW | ~20 panels | ₱500,000 - ₱620,000 |
₱20,000+ | 12-16 kW | ~22-27 panels | ₱600,000 - ₱900,000 |
Prices based on 2026 Philippine market rates with installation.
Why This Formula Works
At ₱11/kWh (average Meralco rate), a 1kW solar system produces roughly ₱1,350-₱1,650 worth of electricity per month in the Philippines (based on 4.5 peak sun hours/day).
So dividing your bill by ₱1,500 gives you the sweet spot — enough solar to offset 80-90% of your consumption.
Factors That Affect Your System Size
Roof space — Each 550W panel is about 2.3m x 1.1m. A 5kW system needs roughly 25-30 sq.m. of unshaded roof space.
Roof direction — South-facing roofs in the Philippines get the most sunlight. East/west roofs lose about 10-15% production.
Shading — Trees, nearby buildings, or water tanks casting shadows on your panels can reduce output by 20-40%. Avoid shaded areas.
Future electricity needs — Planning to add an aircon or EV charger? Size up by 1-2 kW now. It's cheaper than adding panels later.
Grid-Tied vs. Hybrid Affects Cost
The same 5kW system costs very differently depending on type:
Type | 5kW System Cost | Includes Battery? |
|---|---|---|
Grid-Tied | ₱180,000 - ₱230,000 | No |
Hybrid | ₱280,000 - ₱350,000 | Yes (4.8-5.12 kWh) |
Grid-tied is 30-40% cheaper because you skip the battery. But you lose power during outages. Choose based on your area's grid reliability.
Don't Oversize
A common sales tactic: installers push a 10kW system on someone with a ₱5,000 bill. You'll produce way more than you consume, and the net metering credit rate in the Philippines is lower than the retail rate — so you lose money on the excess.
Rule of thumb: Size your system to cover 80-90% of your consumption, not 100%.
Try It Yourself
Use our free Solar Quotation Tool to:
Select your system size and type
Choose from 15+ panel and inverter brands
See the full Bill of Materials with pricing
Get your estimated payback period and savings
It takes less than 2 minutes and it's 100% free.
Engr. Jason Morales
Founder, SolarEnergyPH