Dayboro Solar Panel Output Calculator
Forecasts powered by the Dayboro Model — real local weather data, not Brisbane averages
This calculator uses hourly solar radiation forecasts from the Dayboro Model weather system — a numerical weather prediction model calibrated against real measurements from a station in the Dayboro valley at 130 metres elevation. Unlike every other solar calculator in Australia, which relies on historical BoM averages or satellite-derived estimates, this tool shows you what your panels are predicted to produce today and this week based on actual forecast conditions.
Enter your panel configuration below. You can add multiple strings if your panels face different directions — most Dayboro homes have panels on at least two roof aspects. The calculator accounts for your panel orientation, tilt angle, system age, and panel technology to give you an hourly production forecast you can use to plan your electricity usage.
How This Calculator Differs from Generic Solar Tools
Every other solar calculator available in Australia — SolarQuotes, Solar Choice, solarcalculator.com.au, even the government-backed SunSPOT tool — uses one of two data sources: Bureau of Meteorology historical averages for the nearest capital city, or satellite-derived solar radiation estimates averaged over years. Neither approach captures what actually happens in a specific valley location on a specific day.
The Dayboro Model runs a full numerical weather prediction every day, producing hourly forecasts of solar radiation (Global Horizontal Irradiance), cloud cover at five altitude layers, temperature, humidity, and wind for the Dayboro valley specifically. This calculator takes that hourly GHI data and converts it to panel-level power output using established photovoltaic physics.
Understanding Dayboro's Solar Microclimate
Based on 59 days of measured data from an 11.475 kW system in the Dayboro area (December 2025 to February 2026), here is what the numbers actually show:
| Metric | Measured Value Dayboro, Dec 2025–Feb 2026 |
Generic Brisbane Estimate Sources listed below |
|---|---|---|
| Average daily production per kW | 2.97 kWh/kW | 4.69 kWh/kW (PVGIS ERA5 1994–2023, optimal N-facing, 28° tilt) |
| Best day (clear, low humidity) | 56.6 kWh (4.93 kWh/kW) | Up to ~7–8 kWh/kW (clear spring day; PVGIS best monthly avg 5.27 kWh/kW in September) |
| Worst day (heavy overcast/rain) | 1.9 kWh (0.17 kWh/kW) | 0.05–0.15 kWh/kW (storm/heavy cloud, derived from BoM daily solar exposure dataset IDCJAC0016) |
| NE-facing panels (25° azimuth) | 3.11 kWh/kW/day | ~4.4–4.6 kWh/kW/day (NE ≈95% of optimal north per SolarQuotes; ~97–98% at only 25° from north) |
| SW-facing panels (205° azimuth) | 1.44 kWh/kW/day | ~3.8 kWh/kW/day (SW ≈82% of optimal north; Regen Power) |
| Average self-sufficiency | 77% (with battery) | 30–50% solar only; up to 76% with battery (ScienceDirect, 2025) |
Sources: PVGIS ERA5 (1994–2023) — APVI Brisbane Solar Potential 2018 — SolarQuotes orientation guide — Regen Power orientation data — BoM solar exposure dataset — ScienceDirect: PV-battery self-sufficiency Australia (2025)
The gap between measured Dayboro production and generic Brisbane estimates is significant. A homeowner using a standard online calculator might expect their 6.6 kW system to produce 25 kWh per day. The actual measured average in the Dayboro valley is closer to 20 kWh. That 14–20% shortfall matters when you are sizing a battery, calculating payback periods, or deciding whether to run your pool pump on solar.
Orientation Matters More Than You Think
The data from our reference system tells a stark story about panel orientation. The north-east facing strings produce 3.11 kWh per kilowatt per day, while the south-west facing string manages only 1.44 kWh/kW — less than half. And this is in summer, when the sun tracks high overhead and orientation differences are at their smallest. In winter, the gap widens further.
The calculator above uses hourly irradiance data from the Dayboro Model to calculate output for your specific panel azimuth and tilt — no generic orientation tables. On days with morning cloud clearing to afternoon sun (common in the Dayboro valley), west and north-west orientations can actually outperform north because the afternoon sun hits them when the sky is clearest.
How to Use This Calculator
- Find your panel size — check your inverter display, your solar installer's documentation, or your electricity retailer's records. Common residential sizes are 5 kW, 6.6 kW, 8 kW, and 10 kW. If you have panels on multiple roof faces, add each as a separate string.
- Select your panel direction — which way does your roof face? If you are unsure, stand at your front door at midday: if the sun is to your left, your panels probably face north-east. Most Dayboro homes have roofs running roughly NE/SW due to the valley orientation.
- Enter your roof pitch — standard Australian roof pitch is 22–26 degrees. If you do not know, 26 degrees is a safe default for most Dayboro homes.
- Set your installation year — panels degrade over time. Monocrystalline panels lose approximately 0.5% output per year, polycrystalline about 0.7%. A 10-year-old system produces roughly 5% less than when new.
- Click Calculate — the results show your estimated daily kWh and an hourly production curve calculated from live forecast irradiance data, so you can plan exactly when to run heavy appliances for each day of the week.
Methodology
Data Source
Hourly solar radiation forecasts from the Dayboro Model numerical weather prediction system. The model produces forecasts for Global Horizontal Irradiance (GHI), sun altitude, temperature, and cloud cover at five atmospheric layers.
GHI Decomposition
Total horizontal irradiance is split into direct normal (DNI) and diffuse horizontal (DHI)
components using the Erbs et al. (1982) correlation. This model uses the
clearness index kt = GHI / (I0 × sin(altitude)) where I0 is the
extraterrestrial irradiance corrected for Earth-Sun distance.
Plane-of-Array Transposition
Horizontal irradiance components are converted to the tilted panel surface using the isotropic sky model (Liu & Jordan, 1963). This accounts for beam radiation angle of incidence, isotropic diffuse sky radiation, and ground-reflected radiation (albedo = 0.2).
Temperature Derating
Cell temperature is estimated using the NOCT (Nominal Operating Cell Temperature) model at
45°C. Output is derated at -0.4%/°C above the 25°C standard test
condition, matching typical silicon cell behaviour.
System Losses
Combined system loss factor of 0.894, comprising: inverter efficiency (96%), DC wiring losses (98%), soiling (97%), and module mismatch (98%). These are industry-standard assumptions for a well-maintained residential system.
Calibration
The model is continuously validated against actual production data from a local 11.475 kW Sigenergy system with three panel strings. Per-string calibration factors are computed from historical predicted-vs-actual comparisons and stored for ongoing self-learning improvement.