Two High Voltage Solar Arrays connected to one Terraformer cultivating the desert.
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 cropland).
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/Item, 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.