Thanks. I assumed the section with the solar panels somehow retracted the panels before re-entering the atmosphere, but they skip that part, and I now see that the part re-entering is actually a bit smaller.
It's not a complete waste though. I believe at the ISS they usually pack those sorts of parts (parts that burn up that is. Other examples being the Russian "Progress" spacecraft or the ESA's ATV) full of garbage before sending them off. Intact reentry volume/mass is valuable (currently only the Soyuz and the Dragon can do that) so they just let all of their trash burn up. Here's a neat picture of the first ATV, carrying a bunch of ISS trash, burning up: http://en.wikipedia.org/wiki/File:Jules_Verne_Automated_Tran...
