Quotecom.rakosmanjr.heliostatpower.gui.machine.ContainerMetalWorker.<clinit>
This here is your real problematic mod, not IC2. My best idea is HeliostatPower is using the old API, or your version of IC2 is too old for the API being used, thus the error with IC2's installation. (Big changes with IC2 and IC2 Experimental = cause crashes with other mods that have not updated)
Check your versions, making sure both are for your Minecraft version and both compatible with each other.