Dear respected Hasan A Al-Asadi, it depends on some factors such as angle of incidence of the solar energy on the solar panel (solar angle), the type of material in which the solar panel is made from. In general, when the angle of incidence of the solar energy is 90 ° the solar panel's absorptivity of the solar energy is about 90 % indicating that around 10 % of the sunlight is reflected. Only 6 % to 20 % of this energy absorbed is converted to electricity. The other 94 to 80 % is converted to heat. As the angle of incidence of the solar energy decreases the absorptivity of this energy also decreases.

Best regards

Kifilideen.

1)

https://www.quora.com/What-percentage-of-sunlight-is-directly-reflected-by-a-solar-panel

2) https://www.reddit.com/r/askscience/comments/1qgvs4/how_much_energy_is_lost_from_reflection_on_solar/

3)

https://physics.stackexchange.com/questions/170664/shouldnt-solar-cells-be-nonreflective

It depends on the coatings applied and the cell's construction.

Figures between 3 to 20% appear to be possible.

Dear respected Hasan A Al-Asadi, it depends on some factors such as angle of incidence of the solar energy on the solar panel (solar angle), the type of material in which the solar panel is made from. In general, when the angle of incidence of the solar energy is 90 ° the solar panel's absorptivity of the solar energy is about 90 % indicating that around 10 % of the sunlight is reflected. Only 6 % to 20 % of this energy absorbed is converted to electricity. The other 94 to 80 % is converted to heat. As the angle of incidence of the solar energy decreases the absorptivity of this energy also decreases.

Best regards

Kifilideen.

Dear respected Hasan A Al-Asadi, anti-reflective coating on the surface of the solar panel can help to reduce the amount of solar energy reflected.

Best regard

Kifilideen.

Thank you for the answers.

Thank you James Garry , Ibrahim and Lekan.

But I need references or website of a company including that.

I don't see any answers that mention the spectral response of the reflective surface. There are good reasons for having very high reflectivity in the bands outside the response of the PV material - it will help prevent overheating. Don't forget that antireflection coatings if tailored to some specific spectral response can be as expensive as the panel itself. This suggests that there is some optimisation possible here. Maybe a good masters project?

it depends on many factors which are mentioned previously , the losses related to reflectance not is very important (2-6%) in conventional PV Solar technology, but it will be more effective in concentrated PV Solar technology (CPV), which due to the high value of solar irradiance for example more than 10 sun.

Regards

As Tony Maine mentioned, the reflectivity of the solar panel cannot give the full picture. Each type of solar cell have different spectral response and glass needs to be designed accordingly.Let's consider m-Si, CIGS , CdTe, a-Si have same efficiency and area. Even if we use a glass of only 4% reflectivity. the power delivered will be different as they all (including glass) have different spectral response .

Raviteja, your curve is instructive - but it's a bit more complicated than that. The voltage produced by the panel depends on the cutoff wavelength, or energy per photon, while the current produced by the panel depends on the number of photons absorbed. I haven't seen a spectral response curve that plots number of photons versus wavelength - but it would be easy to create just by dividing the vertical axis by the energy per photon h/lambda. It does give a rather different picture than the one usually shown.

Any reflection of a glass plate can be calculated by the Fresnel equations as a function of angle of incidence and index of refraction (which varies slightly with wavelength). Adding an antireflection coating complicates the calculation, in particular because of spectral properties. For details, see

Article Window optics

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I recommend @Tony Maine Answer