Hourly irradiance received by a panel sometime greater than solar radiation

grasshopper honeybee
,
1

Hi everyone !
I’m currently studying the potential of a PV panel into a roof, using the HB Annual Irradiance component.

What surprises me is that the hourly energy received by the panel (in W/m²) is sometimes greater than the sum of the normal and diffuse solar radiation (also in W/m²), by up to 17%.

How can the energy received by greater than the energy available?
Is there something that I am misinterpreting?

I have to precise that the panel is fixed, not following the sun path.

I’m sorry if the question has been asked before, I haven’t found it in the forum.

Thank you for your help !
Best.

2

Hi @loicw,

A few reasons I can think of:

  • Diffuse horizontal radiation is on a horizontal plane, an inclined plane may receive greater diffuse radiation
  • Reflections from other surfaces
  • Ground radiation, I think by default HB has a “glow” for the ground, mirroring the sky but 20% power by default.

Would be interested if this answers it or if there’s more to it I’ve missed.

Cheers,
Charlie