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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?

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EchoStar XV, EchoStar XXIII and XM-5 are all cited to have 18 to 20kW arrays, launched in 2010 and 2017. These are based on 20kW version of SSL 1300 bus.

The exact numbers are hard to find, as some sources use maximum design capacity of the bus, some sources use launch-time power, and some end of life power.

EchoStar-23 is one of SpaceX’s heaviest payloads to date, weighing around 12,000 pounds (5,500 kg). It carries a pair of X-shaped solar array “paddles” and can support an operational life span at geostationary altitude of 15 years. It is expected that the satellite’s End-of-Life (EOL) power will be in the region of 20 kilowatts

Reference

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  • $\begingroup$ OK, 20 kW > 18 kW so it sounds like the answer to the question might be no, ViaSat 2's 18 kW is not the largest. Can you add a link to your answer showing the source of the 20 kW value? Thanks! $\endgroup$
    – uhoh
    Commented Oct 19, 2017 at 0:15
  • $\begingroup$ Searching for SSL 1300 20 kW I found these for example: 1, 2, 3 and Wikipedia: Total broadcast power ranges from 5 to 25 kW. I also found this mention of the SSL 20.20 with power of 17-30 kW, but the list of satellites seems to be empty. $\endgroup$
    – uhoh
    Commented Oct 19, 2017 at 0:49

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