Solar energy radiation or transmission are through energy bundles called photons, hence thickness accumulation would not be uniform, could not be measured accuratly.....

Photons don't possess any known size either, so can't produce anything called thickness.Radiation is a flux - a flow of energy normal to some chosen surface. There is no meaning to any spatial measurement of radiation flux along that normal, only at right angles to it.

May I ask exactly what it is you are trying to measure?

Intensity can be measured not the thickness sir.

I think photons have some mass. If it have mass ,than possible to have some nano scale thickness.

But our panel output voltage generation, variation with temperature every thing we are calculating with respect to intensity not in terms of thickness.

photons are almost, mass less energy bundles...

What kind of solar radiation do you want to measure;

direct, diffuse or total solar radiation?

Photons do not have mass, you can only attribute a momentum.

Photons do not have mass, you can only attribute a momentum.

I agree with Dr. Erik Strub

As a quantum particle, the photon has a size delta x that can be estimated from Heisenberg uncertainty principle.

According to Heisenberg principle:

delta x delta p => h/2 pi with h the Planck constant and delta p is the mementum of the photon. The momentum of the photon p= mc= Ep/ C, where Ep is the photon energy and C the speed of light in space. We have Ep= hc/lambda, where lambda is the wavelength of the photon. Then one gets p= h/Lambda, which is the de Broglie postulate for the periodicity for the electrons.

Finally one gets delta x= h lambda/2 pi h= Lambda/2 pi

So the uncertainty in measuring the position of a photon is Lambda/ 2 pi. Such uncertainty can be considered the possible size the photon.

Some rule of thumb estimates the size of the photon to be in the order of the wavelength: https://briankoberlein.com/2015/04/14/thats-about-the-size-of-it/

Best wishes

The solar radiation is electromagnetic radiation composed of very small tiny building units called photons. The photon is a quantum of energy Eph having specific wavelength lambda such that Eph= hf= hc/lambda. Photons as a burst of electromagnetic waves are confined in space and limited in size. Their size can be determined as i introduced in my previous comment.

During their transmission they behave as electromagnetic waves and in their interaction with material they behave as particles in the sense they are confined in space and have limited size. They can be absorbed by electrons in materials if they are energetically suitable. For example in a solid material with an energy gap Eg, the photon energy must be equal or greater than Eg to be absorbed.

Assuming that a flux of photons is incident on an absorbing material, they will not be absorbed once they enter the material , but they will be absorbed successively and their number will decay exponentially as they propagate inside the material.

So the photon intensity decays as

I=I0 exp -alpha x,

where alpha is the absorption coefficient and x is the distance from the incidence plane. Accordingly one can define an average distance traveled by the photons before they absorbed. This distance is =1/alpha. The average absorption length.

Alpha is a characteristics of the material and wavelength.

Best wishes

Thank you for comprehensive answer.