Tier 1 power generation: A generator
Tier 2 power generation: Four generators
Tier 3 power generation: Twenty generators
Tier 4 power generation: A hundred generators
Tier 5 power generation: A hundred geothermal generators
Tier 6 power generation: Spam solars everywhere until your world gets corrupted or you run out of resources
Welcome to IC2 power generation.
Also, to your question of LV, MV, and HV, they stand for voltage. Low voltage, medium voltage, and high voltage. (Gregtech introduces extreme voltage and quad-extreme voltage)
You can have unlimited current running through a cable, but it has to be in packets of either 32, 128, or 512.
All machines accept EU in packets of 32 (LV)
Some machines accept EU in packets of 128 (MV)
Only a few machines accept EU in packets of 512 (HV)
HV machines can accept MV, and MV machines can accept LV, but LV machines can't accept MV, and MV machines can't accept HV.
Bat boxes store a small amount of energy, and output their energy in LV.
MFEs store a decent amount of energy, and output their energy in MV.
MFSUs store the most energy, and output their energy in HV.
To convert between voltages, you need a transformer. Set it up so that the 3 dots are facing the higher voltage, and the single dot is facing the lower voltage. Example:
An MFSU storing energy, outputting into an MV transformer, sending power to a bunch of MV-requiring machines.
A bat box storing energy, outputting into an MV transformer, outputting into an HV transformer, to power a few HV-requiring machines.
Transformers don't work infinitely fast, so it's possible to bottleneck your energy output with them accidentally. If you hook up an MV current to an MFE, that MFE is getting 128 EU per tick. However, if you hook up an MV current to an LV transformer, and hook it up to a bat box, that bat box will be getting 32 EU/t. A solution to this is to hook up another LV transformer to the bat box. The bat box will then be getting 64 EU/t, rather than 32 EU/t.