Methodology & Data Sources
Every volatile number on this site lives in one versioned dataset. Each entry carries the date we last verified it and the source we verified it against. If a number on any page looks off, this table is the ground truth.
| Data point | Current value | As of | Source |
|---|---|---|---|
| Meralco overall residential rate | 14.7424 PHP/kWh | 2026-09 | source for Meralco overall residential rate |
| Meralco generation charge | 9.2504 PHP/kWh | 2026-07 | source for Meralco generation charge |
| Net-metering export credit | 5–6.5 PHP/kWh | 2026-06 | source for Net-metering export credit |
| Grid-tie solar cost per kWp (installed) | 35000–55000 PHP per kWp, grid-tie installed | 2026-05 | source for Grid-tie solar cost per kWp (installed) |
| Peak sun hours (PH average) | 4–5.5 kWh/m2/day | 2026-01 | source for Peak sun hours (PH average) |
| System performance ratio | 0.8 ratio | 2026-01 | industry standard for grid-tie systems (inverter, wiring, temperature losses) |
| Typical panel wattage | 580 W | 2026-05 | source for Typical panel wattage |
| Panel area | 2.6 m2 | 2026-05 | manufacturer datasheets, 550-620 W class |
| National residential payback reference | 3.1 years | 2026-06 | source for National residential payback reference |
Per-utility residential rates (Meralco, VECO, Davao Light, MORE Power) live on the rates tracker, same monthly cycle and per-entry sourcing.
Update cycle
Meralco publishes its monthly rate advisory around the 11th–13th; we update the dataset and rebuild the site the same week. Solar pricing is re-checked against published installer price lists roughly quarterly. The dataset's git history is the changelog.
Calculator formulas
- Bill → usage: monthly kWh = bill ÷ current overall rate.
- Solar sizing: kWp = daily kWh ÷ (peak sun hours × 0.8 performance ratio).
- Production: kWh/year = kWp × peak sun hours × 0.8 × 365.
- Payback: cost ÷ (self-used kWh × full rate + exported kWh × export credit).
- Appliance cost: watts × hours/day × 30 ÷ 1000 × rate.
What we deliberately don't do
No lead-selling of your inputs (calculators run entirely in your browser — nothing you type is sent anywhere), no sponsored rankings of installers, and no undated numbers. Estimates are planning figures, not quotes; always compare 2–3 installer quotes. Our full standards are in the editorial policy.
Update log
| Date | Change |
|---|---|
| 2026-07-05 | Dataset created: June 2026 Meralco rate (₱14.4833/kWh), May-final generation charge, 2026 grid-tie install pricing, net-metering export credit range. |
Citing our data
Journalists, researchers, and other sites are welcome to cite any figure or table on this site with attribution and a link — the underlying per-entry sources above are public, and we're happy to explain our verification for any number: contact us.