This item has no texture, name, description, recipe, or uses.
Using FeederHelmet-1.10.2 and jei-1.16.5-7.7.0.106 (Minecraft 1.16.5 & Forge 36.1.10).
I tried adding your Solar Helmet mod, wondering if this was an optional dependency gone wrong, but the useless item remains.

Well the photosynthesis module is an idea which I had previously and also I started to add it. It actually does nothing other than being an useless, uncraftable item.
The main idea is for the helmet to not need food at all. Instead like a solar, the helmet slowly fills up your hunger bar, when in contact with direct sunlight.