Source: nasa.gov; modified
What happened to 2 of the 3 radiators on P6 (solar array) when P6 was moved from Z1 (the top) to its final position on the port side?
Initially I thought 2 were removed and placed on P1 and S1, making the total there 4, with additional 2 later on for the final 6 we see today. One of the sources of confusion is the view after STS-120 (when P6 was moved) where 4 radiators can be seen on P1 and S1 (2 more than before, and 2 fewer on P6), as shown below.
But after checking the ISS guide (PDF; 37 MB), I'm not sure if they're interchangeable, as two types of radiators (I think) are mentioned: Heat Rejection Subsystem (P1 and S2?) and Photovoltaic Radiators (solar arrays?).
Why did P6 not work with just one radiator before and with however many required on P1 and S1?
Information and work on the radiators is sparse on Wikipedia. For example it's mentioned in passing on the STS-120 page, simple stating:
P6 aft radiator shroud installations [...] S1 radiator configuration.
Which doesn't tell much really. For good measure I watched the STS-120 Post Flight Presentation. Again, little to none on the work done on the radiators.
Source: wikimedia.org; modified