Estimate annual grid-connected solar production, monthly solar harvest curves, and utility grid offset metrics.
Comparing monthly solar generation against baseline consumption.
Accurate solar production modeling is the foundation of any viable PV system design. Regional climate differences mean a 6 kW solar system in sunny Arizona will generate significantly more electricity than the same system in Washington or New York. By modeling peak sun hours (PSH) alongside mounting configurations and module efficiencies, designers can project realistic production curves that ensure the system satisfies both grid constraints and user demands.
Furthermore, system derating factors (such as module efficiency losses, inverter inefficiencies, wiring losses, and dirt buildup) must be calculated to model real-world output. Neglecting these derating factors leads to over-estimating yield, creating unrealistic payback expectations for the customer. Using standard PV Watts methodology, our estimator calculates composite technology derates to present a reliable baseline for ROI calculations.
By combining orientation factors with local irradiance data, solar installers can optimize tilt and azimuth, maximizing annual energy offset and minimizing utility charges. This level of modeling is essential for creating compelling, data-backed customer proposals and meeting local interconnection guidelines.
A developer is modeling an 8.0 kW fixed roof-mounted solar array for an office building in Phoenix, Arizona. The panels will be installed at a 30° tilt oriented directly to the south (180° azimuth) using standard monocrystalline panels.
Inputs: System size = 8.0 kW-DC, State = Arizona (6.5 Peak Sun Hours), Mounting = Fixed Roof Mount (0.84 derate), Tech type = Standard (85% efficiency), Tilt = 30°, Azimuth = 180°.
Calculation: Arizona's baseline PSH is 6.5. Standard module efficiency (85%) combined with fixed roof mounting (84% derate) and 4% other system losses gives a composite derate of: 0.85 × 0.84 × 0.96 = 0.685. At 30° tilt and 180° azimuth, the orientation factor is 1.0. The annual production is: 8.0 kW × 6.5 PSH × 365 days × 1.0 orientation factor × 0.685 derate = 13,001 kWh/year. Specific yield is 13,001 / 8.0 = 1,625 kWh/kW.
Result: Estimated annual solar yield = 13,001 kWh. If the baseline electric utility rate is $0.18/kWh, the first-year value of the generated solar power is approximately $2,340, which the installer can confidently integrate into the ROI analysis.
Peak sun hours (PSH) represent the equivalent number of hours per day when solar irradiance averages 1,000 watts per square meter (the standard intensity used for rating solar panels). A location receiving 5 peak sun hours is getting the same amount of solar energy as if it received 5 hours of full, intense midday sun. This metric simplifies annual production modeling across different geographical zones.
State-level estimates use average regional peak sun hours and represent a strong baseline for initial project design. However, local microclimates, specific shade profiles, and rooftop layout constraints will introduce minor variations. For final engineering designs and performance guarantees, installers use precise local meteorological database coordinates (e.g., TMY3 weather files).
Single-axis tracking systems dynamically rotate panels to follow the sun's path from east to west throughout the day, increasing energy yield by 15% to 25% compared to fixed-tilt mounts. Trackers are highly common in utility-scale and large ground-mount solar arrays, whereas residential installations almost exclusively use fixed-tilt configurations due to roof mounting constraints and lower maintenance costs.
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Project: N/A
Designer: N/A
Date:
| System Size: | 6.0 kW |
| Location State: | California |
| Mounting Setup: | Fixed Roof Mount |
| Module Type: | Standard |
| Array Tilt / Azimuth: | 20° / 180° |
| Annual Production: | 9,850 kWh |
| Specific Yield: | 1,641 kWh/kW |
| Grid Bill Offset %: | 102.6% |
| Annual Value of Power: | $1,773 |
| Orientation Loss Factor: | 98.2% |
| Month | Solar Production | Baseline bill | Net Grid Share | Utility Savings |
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This report is for informational and educational sizing purposes. Calculations comply with standard engineering formulas.
Generated by Solaricy — solaricy.com/tools/pv-watts-estimator