How Much Does Solar Actually Save? Run the Numbers Yourself
Most savings estimates are produced by someone who benefits from them looking good. Here's how to run your own, with your own bill, in about five minutes and nothing fancier than a calculator.
What you need in front of you
- Your monthly bill in pesos
- Your monthly consumption in kWh, printed somewhere on that bill
- Your effective rate: divide the pesos by the kWh
- A quoted system price and its size in kW
Step one: what it'll generate
A solid planning figure for the Philippines is 1 kW of well-oriented panels making about 4 kWh a day, averaged across the year. That already allows for night, weather and system losses. It's deliberately a bit pessimistic. A good site in April beats it comfortably; August does not.
So 5kW gives you roughly 20 kWh a day, call it 600 kWh a month.
Step two: what that's worth (the part that gets fudged)
Generation is only worth your full retail rate if you use it yourself. Anything exported earns the net metering credit instead, around ₱5.20/kWh against a retail rate well above that.
So split the generation in two: self-consumed at your effective rate, exported at ₱5.20.
How you split it depends entirely on your household. Empty house on weekdays? Maybe 40% self-consumed. Somebody home, a pump running, aircon in the afternoon? 70 to 80%. This single assumption swings the final answer more than anything else on the page, which is exactly why a proposal that doesn't state it isn't telling you much.
Step three: a worked example
A household paying ₱8,000 for 640 kWh. Effective rate ₱12.50/kWh. They put in 5kW making about 600 kWh a month and use 60% of it themselves.
- Self-consumed: 360 kWh × ₱12.50 = ₱4,500
- Exported: 240 kWh × ₱5.20 = ₱1,248
- Monthly: ₱5,748, about 72% off the bill
- Yearly: ₱68,976
Against roughly ₱300,000 installed, simple payback lands near 4.3 years. Panels carry performance warranties measured in decades, so everything after that is return.
What that simple sum leaves out
Being straight about this matters more than the headline figure.
- Tariffs rise. When they do, your savings rise and payback shortens. Most estimates assume today's rate forever, which understates things.
- Panels degrade. A fraction of a percent a year. Small, but it compounds over twenty.
- Inverters don't last as long as panels. Budget for one replacement somewhere in the system's life.
- Batteries change everything. A battery rarely pays for itself on savings alone. You buy it to keep working through a brownout, which is a different kind of return and shouldn't be smuggled into a payback figure.
- Cleaning. Modest, not zero. Coastal and dusty sites need it more often.
When it doesn't pay
Sometimes it doesn't, and you deserve to hear that. Low consumption, a roof that faces mostly south, heavy shade from a neighbour's tree, or plans to move in two years. Solar is a long-horizon purchase and the maths has to survive that horizon.
Want this run on your actual bill instead of an example? Send us your monthly consumption. We'll size something and quote it itemized, with the self-consumption assumption written down where you can argue with it.
Run it on your real bill
An example is only ever an example. Your roof, your consumption and your daytime habits will move that payback figure in either direction, sometimes considerably.
If you're considering solar, send us a photo of a recent bill on Messenger or give us a ring, and we'll do this calculation properly with your numbers and show you the working. Prefer to talk in person? Come by the shop in Concordia, Bolinao.