Mapping of global radiation onto the earth's surface in the model

Hi Everyone,
I am currently sitting on my master thesis and trying to map the global radiation at the earth's surface for my subsurface model.

I have converted the monthly sum from kWh/m² to j/m2/ d for the mapping.

e.g. for January
20 kWh/m2 --> 26,88 w/m² --> 2.322.580,65 j/m²/d
because inflows in Feflow are negative accordingly -2.322.580,65.

I have mapped the months over a Time Series, with a Heat-Flux BC.

Unfortunately, the results and the temperatures are much too high. Unfortunately, I do not know what the reason could be.

About any help in this regard I would be very grateful  :)

Only putting global radiation at the surface will very likely overestimate the heat inflow. On the one hand, you'd probably need to consider albedo. On the other hand, there will also be radiation back into the atmosphere, plus conductive heat flow, ...

Thank you very much. I totally forgot to mention that.
in german we say: Sometimes you can't see the forest beyond all the trees.    ;D