Bifacial irradiation

[Pablo HM]

If we start with a base of 715 kWh/m2 incident on ground and we apply all losses and gains that appears in the Sankey diagram attached, we obtain an effective Global Irradiance on rear side on collectors of 60,96 kWh/m2.

There is a lot of discrepancy between both results. If we do the same calculation for the front side, we don't have any problem. Why is this happening? Do we have to consider anything else as configuration 1P, 2P... or other variables?

 

[Pepe Rod]

It happens exactly the same to me. I have not been able to find an explanation.

[tanzale33]

a small world cup  

On 2/16/2024 at 6:43 PM, Pablo HM said:

If we start with a base of 715 kWh/m2 incident on ground and we apply all losses and gains that appears in the Sankey diagram attached, we obtain an effective Global Irradiance on rear side on collectors of 60,96 kWh/m2.

There is a lot of discrepancy between both results. If we do the same calculation for the front side, we don't have any problem. Why is this happening? Do we have to consider anything else as configuration 1P, 2P... or other variables?

They can represent different panel installation configurations that affect rear radiation. For example, a single axis tracker (1P) may have different shading and reflection characteristics compared to fixed tilt (2P) or other installations.

[Michele Oliosi]

The discrepancy is because the area is not the ground anymore, but the module area.
With a GCR of about 50%, 1 m^2 of ground is about 0.5 m^2 of module backside area. Proportionally, the energy per unit area is doubled.