Now that the protests at Kourou Space Center in French Guiana are over, Arianne has launched both EutelSat 172B and ViaSat-2 as
2017-029A. While EutelSat 172B has a photovoltaic power of about 13 kW, ViaSat-2 has 18 kW.
VS: What is the lifespan of the ViaSat-2 satellite and how is it powered?
RD: ViaSat-2 has a lifespan of about 14 years and is powered by a solar array that generates nearly 18kW of power as well as Lithium Ion batteries. The vehicle maintains it orbital location for 14 years using xenon ion propulsion (electric propulsion).
This seems to be the top end for the Boeing 702HP Bus.
Innovation extends to the Boeing 702 power systems as well. The Boeing 702 offers a range of power up to 18 kW. Dual and triple-junction gallium arsenide solar cells enable such high power levels. Spectrolab, Inc. a Boeing subsidiary, developed the cells.
Question: Is an 18 kW solar array the largest to ever be deployed for a commercial telecom satellite?
The article continues with more power-related information on the 702HP bus...
The first version of the 702 used solar arrays with concentrators. These concentrators tended to early fogging, as due to an inherent design flaw the outgassing of the solar cells was higher than expected. This fogging lead to much reduced lifetime. The flaw was corrected in later versions with higher power triple-junction gallium arsenide solar cells.
See Were solar concentrators on HS-702 just a stop-gap measure until triple-junction PV cells were available?
The Boeing 702 separates the bus and payload thermal environments and substantially enlarged the heat radiators to achieve a cooler, more stable thermal environment for both bus and payload. This increases unit reliability over service life. Deployable radiators use flexible heat pipes, which increase packageable radiator area. Further thermal control occurs through passive primary rejection via heat pipes.
See What are these very large, square panels on Inmarsat 5's?