Question

Is absorbing solar energy during photosynthesis, considered as an endothermic reaction?

Answer 1

Definitely I would say yes

Explanation:

In endothermic reactions energy is put into the system. The resulting products have more energy than the reactants.
In exothermic reactions energy comes out of the system, The resulting products have less useable energy than the reactants.

Cellular Respiration is the opposite reaction to photosynthesis. Cellular respiration is an exothermic reaction so photosynthesis being the opposite is an endothermic reaction.

Photosynthesis requires energy from the sun to be put into the system meeting the the definition of an endothermic reaction.