How Many Solar Panels Do I Need? (Philippines)
TL;DR
Divide your monthly bill by about 13 to 14 (your all-in Meralco rate per kWh) to get monthly kWh, then divide by 120 to get system size in kW. Panel count is roughly kW × 2, since most residential panels are 450-600W. A ₱6,000 bill needs about a 3kW system, or 6 panels.
For a typical Philippine home, the answer works out to roughly 2 panels per kW of system size — so a household with a ₱6,000 monthly electric bill needs about a 3kW system, or 6 panels. The exact count depends on your bill size, your panel wattage, and how much roof space you have to work with.
What’s the formula for figuring out panel count?
The formula runs from your bill to your system size in three steps.
- Bill → monthly kWh. Divide your average monthly electric bill by about 13 to 14 (your all-in Meralco rate per kWh). A ₱6,000 bill works out to roughly 444 kWh a month.
- kWh → system size. Divide that monthly kWh figure by 120. 444 kWh ÷ 120 is roughly 3kW.
- kW → panel count. Panels are typically 450-600W each, so panel count comes out to roughly kW × 2. A 3kW system needs roughly 6 panels.
This isn’t exact science — actual sizing also depends on sun exposure, shading, and roof orientation — but it’s a solid starting estimate before talking to an installer.
How much system size and roof space does each bill size need?
Here’s how that math plays out across common Philippine electric bills:
| Monthly bill | Est. monthly kWh | Est. system size | Est. panel count | Est. roof space |
|---|---|---|---|---|
| ₱4,000 | ~296 kWh | ~2kW | ~4 panels | ~14-18 sqm |
| ₱6,000 | ~444 kWh | ~3kW | ~6 panels | ~21-27 sqm |
| ₱8,000 | ~593 kWh | ~5kW | ~10 panels | ~35-45 sqm |
| ₱12,000 | ~889 kWh | ~8kW | ~16 panels | ~56-72 sqm |
Roof space is estimated at roughly 7-9 sqm per kW, which covers the panels themselves plus mounting clearance. If your roof is smaller than the estimate for your bill, you’ll likely need to either downsize the system or accept a smaller offset of your bill.
Why does the estimate use bill size instead of just asking for kWh?
Because most homeowners know their peso bill, not their kWh usage. The bill is printed on every statement, while kWh consumption often isn’t something people track directly, so working backward from the bill (₱ → kWh → kW → panels) starts from the number people actually have on hand.
Does system size change based on which appliances I run?
Yes. The bill-based formula gives a starting point, but a household running aircon units, pumps, and appliances mostly during the day gets more value out of a given system size than one that’s away until evening, since net metering only credits exported power at roughly ₱5-7/kWh, well below the retail rate. That’s also why realistic bill cuts land around 90%, not 100% — see our is solar worth it guide for when the numbers make sense and when they don’t.
Can I just use an estimator instead of doing the math myself?
Yes — that’s exactly what our cost calculator does. Plug in your monthly bill and it runs the bill → kWh → kW → panel count math automatically, then matches it against current installed pricing so you get a system size and a cost range in one step. You can also check our price pages for what systems of different sizes cost installed in your area.
How does panel count affect payback?
It doesn’t directly — payback depends more on your bill size, your usage pattern, and installed cost per watt than on the raw panel count. A bigger system built for a bigger bill doesn’t pay back faster or slower just because it has more panels. See our solar panel payback period guide for what actually moves that number, typically 3 to 7 years for a grid-tied system.
What if my roof can’t fit the recommended panel count?
Then you’re choosing between a smaller system that offsets less of your bill, or adding higher-wattage panels to fit more capacity into the same roof space. Either way, start with the cost calculator to see how a reduced system size affects your numbers before committing to an installer’s quote.
Frequently asked questions
How many solar panels does a typical Philippine home need?
Most homes need somewhere between 4 and 16 panels, depending on the electric bill. A ₱6,000/month bill points to roughly 6 panels; a ₱12,000/month bill points to roughly 16 panels.
How do I calculate my system size from my electric bill?
Divide your monthly bill by about 13 to 14 (your all-in Meralco rate per kWh) to estimate monthly kWh, then divide that number by 120 to get system size in kW. For example, a ₱6,000 bill is about 444 kWh, which points to roughly a 3kW system.
How many panels equal 1kW?
About 2 panels, since residential panels typically run 450-600W each. A 5kW system usually needs around 8-10 panels.
How much roof space do I need per kW of solar?
Budget roughly 7-9 square meters per kW. A 5kW system needs roughly 35-45 sqm of usable, unshaded roof space.
Does this bill-to-panel-count method account for my actual roof and appliances?
No, it's a starting estimate. Roof shape, shading, orientation, and which appliances you run during the day all shift the ideal system size, which is why the estimator asks for more detail before giving you a final number.
Should I round my system size up or down?
Most homeowners round up slightly, since net metering only credits exports at roughly ₱5-7/kWh while a system sized a bit small still leaves you buying full-price grid power during peak usage hours.