What is solar energy?
Solar energy is the energy in sunlight. A house can use it two ways: solar panels turn it into electricity, and a solar water heater turns it into hot water. This page is mostly about the first, because that is what people mean by solar here, and it ends with how much sun a roof in Pampanga actually gets.
Two ways to use it
- Photovoltaic: sunlight into electricity
- Panels on the roof, an inverter, and wiring to the board. The electricity runs anything in the house. This is what SolarPampanga installs.
- Solar thermal: sunlight into heat
- A collector heats water directly, with no electricity made at all. How a solar water heater works.
How a panel turns light into electricity
The first three steps follow the US Department of Energy, Solar Energy Technologies Office’s explanation of a silicon cell, read 8 October 2026.
- 1
Light reaches the cell
A solar cell is a thin layer of silicon. When sunlight is absorbed in it, the light excites electrons in the silicon.
- 2
The electrons move as a current
The silicon is attached to other materials that let the current flow through it to metal contacts, where it is collected as electricity. This is the photovoltaic effect, and it has no moving parts.
- 3
Cells are wired into a panel
A module, the thing usually called a solar panel, is several cells wired together in a protective casing behind glass.
- 4
The inverter makes it usable
Panels make direct current. The house runs on alternating current, so an inverter converts it before it reaches the board and the sockets.
How much of the light a panel uses
The same US office gives the figures. Monocrystalline silicon was 96 percent of global solar shipments in 2022. Its cells can convert more than 27 percent of the light in ideal laboratory conditions, and industrially produced modules achieve 20 to 22 percent in real use. The newest module datasheets print a little higher: the mono vs poly page reads a current Jinko module’s datasheet at 22.45 to 23.42 percent.
Most of the rest becomes heat, which is why a panel on a hot roof makes a little less than its rating. The datasheet’s temperature coefficient says how much less for each degree.
From the roof to the socket: three kinds of system
All three drawn, with every part named
- Grid-tied
- Panels and an inverter, connected to the utility. The house uses solar first and the grid for the rest, and can export the surplus under net metering. It has no battery and shuts down when the grid does. How net metering works.
- Hybrid
- A grid-tied system with a battery and an inverter that can run chosen circuits when the grid drops. Sizing a battery from its datasheet.
- Off-grid
- Panels, batteries and a charge controller with no utility line at all, for a farm, a resort or a house the lines do not reach. Off-grid systems.
How much sun a roof here gets
The Global Solar Atlas, published by the World Bank Group and ESMAP, on Solargis data and read 23 September 2026, gives San Fernando, Pampanga 1,911 kWh of sunlight on each square metre of flat ground a year. Spread over the year that is about 5.23 peak sun hours a day, and the atlas expects each kilowatt of panels there to make about 4.3 kWh a day on average. The peak sun hours page has the same figures for four more points around Central Luzon, and the cloudy-day article measures what the rainy season does to them.
Across the country, solar made 3.0 percent of the electricity generated in 2024, according to the Department of Energy’s Key Energy Statistics 2024. Solar energy in the Philippines sets out the national figures year by year.
What people ask about solar energy
What is solar energy?
Solar energy is the energy in sunlight. A house uses it in two ways: solar panels turn it into electricity, and a solar water heater turns it into hot water. When people say solar in the Philippines they almost always mean the first, photovoltaic panels on the roof.
How does solar energy work?
In a silicon solar cell, absorbed light excites electrons, and the moving electrons make an electric current that metal contacts collect. That is how the US Department of Energy, Solar Energy Technologies Office describes it. The panels make direct current, and an inverter turns it into the alternating current the house runs on.
Does solar work at night or when it is cloudy?
Not at night: panels make electricity only while light reaches them, so a house with no battery uses the grid after dark. Under cloud they make less. The cloudy-day article on this site measures how much less in San Fernando from two years of NASA daily data.
How much sun does Pampanga get?
The Global Solar Atlas gives San Fernando 1,911 kWh of sunlight per square metre a year, which is about 5.23 peak sun hours a day. It expects each kilowatt of panels there to make about 4.3 kWh a day on average across the year.
Is solar energy renewable?
Yes. The Department of Energy counts it among the renewables in its energy statistics, and in 2024 it made 3.0 percent of the country’s electricity.
Find out what it would do on your roof
Tell us the property and your monthly kilowatt-hours through the form, and you will get a written answer with a system size. If the form is too much, the Message us button at the bottom of the screen asks for less.
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.
Sources: US Department of Energy, Solar Energy Technologies Office, “Crystalline Silicon Photovoltaics Research”, energy.gov, read 8 October 2026, for how a cell works and the efficiency and shipment figures; JinkoSolar module datasheet, as read on the mono vs poly page; Global Solar Atlas, read 23 September 2026, for San Fernando; Department of Energy, Key Energy Statistics 2024, page 45, read 9 October 2026, for solar’s share of generation.