GregTech itself already nerfes the Windmill recipe in particular, base of compact windmills.
Same thing happens with compact solars, as the solar panel recipe is now more expensive.
Compact windmills and Compact solars are not meant to be "expensive", just a way to reduce lagness of tons of generators.
May i suggest adding tiers to rotors?
For example tier 1 rotor (ultra low voltage) requires 2 material items,T2 requires 4, T3 requires 8, tier 4 16 and tier 5 32.
[Achieved by combining two of previous tier to make the next one]
Rotor durability increase 20% base per tier. T1 2 days, T2 2d + 9,6h , T3 2d + 19,2h , T4 3d + 4,8h, T5 4days
Edit: Your wind generation code is "failing", i can generate 170 EU/t near bedrock using a EV windmill and a rotor while it has 9000+ obstructions around.
To make it more precise, please DO use IC² wind formula as base :
Generation = WindStrength * (Height - 64 - Obstruction blocks) / 750 * Weather Value
Wind Strength values from 0 to 30,
Obstruction block is any block within the detection area, you may exclude cables from this calculation somehow,
Weather value is 1,2 if raining and 1,5 if rain + thunderstorm.
ULV windmills, which are 4 windmills would generate 4 times a normal windmill would do.
LV windmills, would generate 16 times a normal windmill would do.
MV windmills, 64 times.
HV, 256x
EV, 1024x