They are not simply two wattage options
REC Alpha Pure-RX 470W and Alpha Pure 2 430W both use heterojunction technology, but their electrical profiles and physical formats differ. The RX 470W record is rated at 22.6% efficiency with 55.4V Vmp and 8.49A Imp. The Pure 2 430W record is rated at 22.2% efficiency with 41.8V Vmp and 10.29A Imp.
RX uses higher voltage and lower current
For a given string power, the RX profile can reduce operating current but raises per-module voltage. That changes how many modules fit inside an inverter’s MPPT voltage window and maximum DC-voltage limit. Cold-weather Voc must still be calculated for the exact site.
Pure 2 can fit different roof layouts
The Pure 2 family is aimed at compact residential applications and reaches 430W in the verified datasheet. Its lower per-module voltage may permit more modules in series on some inverters, while its higher current requires checking MPPT and connector limits.
Efficiency is close enough that layout can decide
The 0.4 percentage-point efficiency difference is real but should not be isolated from roof geometry, shading, string design, local availability and installed price. A system with a cleaner layout and fully compatible electronics can outperform a nominally more efficient module choice.
Use exact regional documents
REC publishes regional variants and certification documents. Verify the datasheet used by the local supplier rather than assuming every market receives the same connector, fire rating or warranty program. Review the source-backed Alpha Pure-RX 470W record and Alpha Pure 2 430W record, then use the cold-weather string-voltage check before final string sizing.