Reading Wikipedia on processes for making electronics-grade silicon, the only process that I thought could loosely translate into the technologies available in minecraft was the zone melting process, involving heating only a section of the crystal to force the impurities to gather on one end, which is later cut off. That's why I suggested an electric or better furnace, to get the required temperature levels and heat control. Of course, it'd be a shame not to also make use of more of the wonderful devices in IC2, so there's certainly the space for more steps. At least there's plenty of IDs for items, so making levels of partially-processed silicon would only be a bother for coding.
And, let's not forget that electronics-grade silicon could have more uses than just for our solar panels. I suggested that maybe using it as the corners for the Advanced circuit recipe. Or, perhaps, combine silicon, tin wire (high-end components nowadays operate at a level ~ 5V) , and a rubber / carbon casing to make semiconductor-level components for something-or-other.