Forge 1.18 38.0.14
Solar helmet 1.2.2

SolarHelmet (solarhelmet) has failed to load correctly
java.lang.NoSuchMethodError: 'net.minecraftforge.fmllegacy.RegistryObject.

Crashlog

You are using the wrong version of solar helmet. You are using the 1.17.1 version, but you need the 1.18 version.
The current 1.18 version is "Solar Helmet 38.0.0"

Whoops ...