Update Forge to 524 (CompactSolars requires 523+).
Update the following mods:

ComputerCraft to 1.5.
Mo'Creatures to 4.5.1.
ExtrabiomesXL to 3.9.0.
Flan's Mod to 2.1.1 for 1.4.7.
GravityGun to 1.4.7v2.
PortalGun to 1.4.7v4.
Railcraft to 6.15.3.0.
Steve's Carts to 2.0.0 alpha 57.
Thaumcraft to 3.0.3.
ThermalExpansion to 2.2.1.
ReiMinimap to 1.4.7 compatible 3.2_06.
BuildCraft to 3.4.3.
CompactSolars to 4.0.2.28.
Forestry to 2.0.0.10.
GregTech to 2.78k.
IndustrialCraft 2 to 1.115.207.
IronChest to 5.0.1.246.
MiscPeripherals to 3.1.
TwilightForest to 1.15.2.