Why is it recommended to not store commercial sodium silicate solutions in direct sunlight, what are the effects of doing so and can it be modelled?

I regularly purchase aqueous sodium silicate solutions from commercial providers for my studies and note that a storage recommendation for all different grades (i.e. differing $\ce{SiO2 / Na2O}$ ratios) is to "not store in direct sunlight" with no explanation as to why this is the case. I tried asking the provider why this is a recommendation but didn't get a substantial answer apart from "*it turns a weird [brown-like] colour after a while and is not really usable after that*".


I believe the issue here is something to do with the polymeric character of sodium silicate - with the formula given as $\ce{Na\_{2x}Si\_yO\_{2y+x}}$ or $\ce{Na2O\_x SiO2\_y}$ - which would inevitably cause issues with sunlight cleaving parts of the sodium silicate polymer backbone and creating a heterogenous mixture (i.e. with different parts of the aqueous solution having polymers of different chemical formulas) which would be a QAQC (quality assurance and quality control) nightmare for using sodium silicate solutions in commercial developments. Adding to this, I believe the poor usability probably comes from precipitation of something and have found (if useful) that sodium silicate solutions with [increased levels of $\ce{Na2O}$ can cause solution precipitation](https://www.sciencedirect.com/science/article/pii/B9781845694494500047).. however this precipitation is a white gel-like substance (which I believe comes from the solution approaching the saturation concentration of $\ce{NaOH}$) and nothing "brown-like".


**My Questions are:**


1. Does anyone have experience/insight here with storing sodium silicate solutions in direct sunlight?
2. What predictive mathematical and/or empirical models can be used and/or made to assess how much sunlight will cause QAQC issues with sodium silicate?


