Terraformers are Machines with the ability to change the terrain around them. The affected area is a little larger than 8 chunks by 8 chunks. The reasons for terraforming are usually to add a desired visual effect that is naturally not possible (Chilling - snow in the nether). Or to change a large area without having to manually do the alterations (Cultivation - turn a desert into a vast farmland).
The power requirements of the Terraformer are much the same as a Quarry. It will work with even the tiniest power input, but its maximum power requirement will vary based on the TFBP it's using.
Note that the Terraformer is an IC2 block, so it requires EU instead of BC power. The Terraformer must be removed with a wrench to be removed properly. Using a wrench on the Terraformer gives back the current TFBP in the Terraformer, so the second usage of wrench removes the Terraformer.
For best results use between 1 and 5 medium voltage solar arrays; a high voltage one works better, but you need a lot of resources, and the difference isn't that large. And if you are using solar panels/arrays, it is preferable to have them charging to a MFE/MFSU so it can work through the night.