All Calculators
☀️

Solar Panel Sizing Planner

Right-size your PV array using site irradiance and loss assumptions based on NREL PVWatts and IEC 61724-1 performance guidelines.

Energy Goal

kWh/yr

Use your annual consumption or PV target contribution.

kWh/kW/yr

Extract from PVWatts/NSRDB for tilt + azimuth.

fraction

PVWatts default ≈ 0.77; adjust with losses below.

kW

Use to assess performance vs target PR.

Loss & Efficiency Inputs

%
%
%
%
%

Mismatch, degradation, shading, availability.

Monitoring Inputs (optional)

kWh/yr
kWh/kW/yr

Use sensor data for IEC 61724-1 PR calculation.

📖 How to Use

Gather your annual energy target and site irradiance from PVWatts or local solar resource data. Adjust losses to reflect system design (inverter efficiency, wiring, soiling, temperature). Use measured production and irradiance to verify performance ratio after commissioning.

🧮 Formula Reference

Required DC size = Annual Load ÷ (H_POA × Derate)
Estimated AC output = DC size × H_POA × Derate
Performance ratio = Measured AC ÷ (Measured irradiance × Array STC)

⚠️ Notes

  • H_POA should reflect array tilt/azimuth; use PVWatts hourly data or TMY dataset.
  • Derate is the product of each loss term: Derate = Π (1 − loss_i).
  • PR calculations require calibrated irradiance sensors; follow IEC 61724-1:2021 for instrumentation.

🔗 References