Peak sun hours in Central Luzon, one town at a time
Ask what the Philippines gets and you are told four to five and a half hours. It is the right range for a country of seven thousand islands and it will not size anything. The five figures below each belong to one set of coordinates, and you can open the atlas at that point and read the same number.
They are close together, which is worth knowing too: from 5.09 at Malolos to 5.31 at Tarlac City, about four percent across the whole of the area this site works in.
How little they differ
Drawn to scale from zero, which is the point. Somebody choosing between provinces on sunshine is choosing on nothing: the whole spread is about four percent.
Five points, five figures
Each row is the atlas's long-term average at the coordinates printed with it. It is that point's figure and not an average of the province around it.
- The point
- 15.028301, 120.693804
- Irradiation over a year
- 1910.5 kWh per square metre. Spread over 365 days that is the figure on the left.
- What the atlas expects a kilowatt to make
- 1555.3 kWh a year for each kilowatt-peak installed, or 4.26 kWh a day. This already has system losses in it.
- The point
- 14.843759, 120.811369
- Irradiation over a year
- 1858.9 kWh per square metre. Spread over 365 days that is the figure on the left.
- What the atlas expects a kilowatt to make
- 1507.8 kWh a year for each kilowatt-peak installed, or 4.13 kWh a day. This already has system losses in it.
- The point
- 14.679567, 120.540969
- Irradiation over a year
- 1923.7 kWh per square metre. Spread over 365 days that is the figure on the left.
- What the atlas expects a kilowatt to make
- 1563.2 kWh a year for each kilowatt-peak installed, or 4.28 kWh a day. This already has system losses in it.
- The point
- 15.486122, 120.589347
- Irradiation over a year
- 1938.6 kWh per square metre. Spread over 365 days that is the figure on the left.
- What the atlas expects a kilowatt to make
- 1583.2 kWh a year for each kilowatt-peak installed, or 4.34 kWh a day. This already has system losses in it.
- The point
- 14.838885, 120.284359
- Irradiation over a year
- 1866.4 kWh per square metre. Spread over 365 days that is the figure on the left.
- What the atlas expects a kilowatt to make
- 1519.0 kWh a year for each kilowatt-peak installed, or 4.16 kWh a day. This already has system losses in it.
The arithmetic checks against the atlas's own answer
A sizing calculation takes peak sun hours and knocks a fifth off for inverter losses, heat, wiring and dust. The atlas publishes its own modelled yield per kilowatt-peak separately, worked out by a different route. The two should agree, and if they did not one of them would be wrong.
Across all five points they agree to within 2.0 percent. That is the reason to trust the performance ratio the sizing tool uses, rather than the reason being that somebody chose it.
Side by side, kWh a day per kilowatt-peak
- San Fernando
- 4.19 from the sizing arithmetic, 4.26 from the atlas
- Malolos
- 4.07 from the sizing arithmetic, 4.13 from the atlas
- Balanga
- 4.22 from the sizing arithmetic, 4.28 from the atlas
- Tarlac City
- 4.25 from the sizing arithmetic, 4.34 from the atlas
- Olongapo
- 4.09 from the sizing arithmetic, 4.16 from the atlas
Using it
The sizing tool on the cost page now runs on these figures rather than the round number it used before. Pick your area and the peak sun hours box fills with that point's value, and you can type over it if you have a reading for your own address.
It ran on 4.0 until today, which was declared as a placeholder in its own assumption line and was understating every one of these five by roughly a quarter.
What people ask about peak sun hours
What are peak sun hours in the Philippines?
A peak sun hour is an hour of sunshine at 1,000 watts per square metre, so it is a way of writing a whole day of varying sunlight as a single number. Most guides answer this question with a national band of four to five and a half, which is true and tells you nothing about your own roof.
At the five points on this page the figure runs from 5.09 at Malolos to 5.31 at Tarlac City. Each is the Global Solar Atlas value at one set of coordinates, printed beside it.
Why not give one figure for the whole province?
Because a province is not a single place and a provincial average belongs to nowhere in it. The capital and the upland barangays do not get the same sun, and averaging them produces a number that is wrong for both while looking authoritative.
So every figure here names its point and its coordinates. If your roof is an hour from the town named, treat the figure as the nearest honest one rather than yours, and the atlas will give you your own for nothing.
How do I turn peak sun hours into panels?
Daily kilowatt-hours you want to cover, divided by peak sun hours, divided by a performance ratio for losses, gives kilowatts-peak of array. The sizing tool on the cost page does it with the figure for whichever of these areas you pick.
The performance ratio is the part people leave out. Inverter losses, heat, wiring and dust take a fifth of it before anything reaches your meter.
Is this the same as hours of daylight?
No, and the gap is large. The Philippines gets roughly twelve hours of daylight all year round. Five of them are worth a peak sun hour.
Early and late sun arrives at a shallow angle through more atmosphere, so it carries much less energy per square metre. Peak sun hours count the energy, not the clock.
Where do these numbers come from?
The Global Solar Atlas, published by the World Bank Group and ESMAP, on Solargis data. Data version 2.2.68, updated 1 April 2026, read on 23 September 2026. The coordinates come from OpenStreetMap Nominatim, read the same day.
Each row links to the atlas at its own point, so you can open it and see the same figure rather than take ours.
The figure for your own roof is the one that matters
These five are the nearest honest numbers, and your roof has its own pitch, its own orientation and its own shade. Tell us the town and we will take it from there.
Tell us the property and what you are trying to cut, and you will get a written answer with a size and a next step. No visit is booked and nothing is charged for asking.
Source: the Global Solar Atlas, published by the World Bank Group and ESMAP, on Solargis data. Data version 2.2.68, updated 1 April 2026, read on 23 September 2026. Coordinates from OpenStreetMap Nominatim, read the same day. Every row links to the atlas at its own point. Nothing here is a promise about what any particular roof will generate, and we will measure yours before we quote anything. How the sunlight becomes electricity is on what is solar energy, and the national picture on solar energy in the Philippines. Send us the details or use the Message us button and we will talk about your actual property.