Nimesh Katariya POA stands for Plane of Array, and POA irradiance is the total sunlight reaching the tilted surface of a PV module, measured in W/m². It adds direct beam, sky diffuse and ground-reflected light, usually calculated from GHI with a transposition model such as Perez (1990). Solar designers use POA irradiance as the main input for energy yield.
What is the full form of POA in solar?
POA full form in solar is Plane of Array. POA irradiance is the sunlight falling on the tilted face of a PV module. This page is for solar designers, yield analysts and O&M teams who need the POA formula and how POA is used in a solar plant.
How is POA irradiance calculated? (POA formula)
POA_total = POA_direct + POA_diffuse + POA_reflected
POA_direct = DNI × cos(incidence_angle)
POA_diffuse = DHI × transposition_factor_diffuse
POA_reflected = GHI × ρ_ground × (1 − cos(tilt)) / 2Where ρ_ground is the ground albedo, the fraction of incident light the ground surface reflects back onto the module’s rear or front face.
Transposition Models
| Model | Use | Accuracy |
|---|---|---|
| Isotropic (Liu-Jordan) | Simple | Lowest |
| Hay (1979) | PVsyst default | Moderate |
| Klucher | Better for diffuse | Good |
| Perez (1990) | Bankable standard | Best |
| Reindl | Variant | Good |
What is the difference between POA and GHI?
| Site | Annual GHI | Annual POA (tilt = latitude) | Transposition factor |
|---|---|---|---|
| Phoenix AZ | 2,100 | 2,350 | 1.12 |
| Bengaluru | 1,900 | 1,990 | 1.05 |
| Boston | 1,400 | 1,580 | 1.13 |
| Germany | 1,050 | 1,180 | 1.12 |
Key Takeaways
- POA = total solar radiation on tilted module surface.
- Direct + diffuse + reflected, transposed from GHI/DNI/DHI.
- Perez transposition is the bankable industry standard.
- POA = GHI × ~1.05-1.20 typically for optimal tilt.
- Bifacial designs compute POA_front and POA_rear separately.
Related Reading
POA irradiance is the direct input that transposition models feed into a plant’s expected energy yield, and it shows up throughout the yield-simulation workflows covered in Solar Simulation Software 2026: Lender-Grade Yield Picks. Because the transposition factor is sensitive to row spacing and shading, engineers building ground-mount layouts often reference our PVsyst 3D near-shading scene builder walkthrough before finalizing tilt and pitch.
On tracker-based plants, backtracking changes the incidence angle used in the POA_direct term hour by hour, a process detailed in PVsyst Tracker Yield Study: Step-by-Step Methodology. Once POA-derived yield numbers are in hand, they typically flow straight into project economics, SurgePV’s solar generation financial modeling tool is built around that handoff from irradiance to revenue projection.
Disclosure: SurgePV is a Heaven Designs group company.
Frequently Asked Questions
4 commonly searched questions about POA Irradiance (Plane of Array).
What is POA in a solar plant?
How is POA irradiance calculated from GHI?
What is the difference between POA and GHI?
Does POA include rear-side bifacial gain?
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