Value chain · CLM-0879
In plain terms
The only two full satellite designs here that say what voltage they run at disagree eight-fold, and the newer, smaller one runs at the lower voltage. The newer design's paper says its modular layout keeps the cables short, about 310 metres, and that this allows the lower voltage.
The claim as recorded
The two full SPS designs in this register that state a satellite bus voltage disagree by a factor of eight, and the later, smaller design uses the lower voltage: the 1978 DOE/NASA reference system specifies 40 kV DC for power transmission from the solar array to the microwave antenna, justified in its own text on power-conductor and conditioning-equipment mass grounds, while CAST's 2025 MMR-SPS states a 5 kV main bus for a 1 GW design. No source in the register reconciles the two; CAST's paper states that its modular layout cuts the array-to-antenna distance to 310 m, which "allows for the use of relatively shorter cables and lower voltage (5 kV)".
Evidence behind this: Derived from two other claims. Tier follows the weakest input: CLM-0210 is T3, CLM-0692 is T2.
Scope and limits
THIS IS A DISAGREEMENT BETWEEN TWO STATED DESIGN CHOICES. IT IS NOT A MEASUREMENT, AND IT IS NOT EVIDENCE THAT EITHER FIGURE IS WRONG. The designs are not comparable in scale or architecture: 5 GW against 1 GW, one antenna against 50 subpanels and 100 rotary joints, and the 1978 report states no conductor run length, so the mass argument that motivates a high voltage cannot be evaluated for it; CAST's paper states its 310 m module cables but no conductor mass. Each source gives one line of reasoning: the 1978 report on conductor and equipment mass, and CAST's paper on shorter cables. The 5 kV was read from a rendered page image because SRC-169's text layer is corrupt on that page - it renders 5.8 as "S.8" and 50 as "so" - and it was read twice, once for CLM-0692 and once independently for this record. That is a statement about the source, not a doubt about the figure. This record marks the disagreement; it does not resolve it.
What it assumes
That the 1978 report's stated voltage is the primary array-to-antenna distribution bus. Its text describes it as power transmission from array to antenna but does not define the term further. No such assumption is needed on the CAST side, where the source's own table labels the figure "main bus".
Where it comes from
CLM-0210 from SRC-085: 40 kV DC for a 5 GW photovoltaic point design, with switchgear and cable insulation for 40 to 50 kV listed as still requiring development. CLM-0692 from SRC-169 Table IV, journal page 118: the PTM subsystem row gives "Voltage of main bus/kV" as 5, printed without the tilde most values in that table carry, for a 1 GW MMR-SPS. SRC-169 PDF p.5 (printed 111): "the electric power transmission distance from the solar panel to the antenna panel is reduced to 310 m along the vertical truss. As a result, it allows for the use of relatively shorter cables and lower voltage (5 kV)".
Related records
- Answers question
- QST-043 not published in this release
Cite this
energyaperture.com/c/clm-0879
CLM-0879, Energy Aperture, as of 2026-09.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-169
- CLM-0141A Chinese government-linked design study calculated that, outside the main beam of its proposed satellite, stray sidelobe power on the...CLM-0142A major Chinese government-linked design paper on a specific space solar power concept does not mention the upper atmosphere at all, and...CLM-0501A 2024 Chinese satellite design concept plans to beam down microwaves twice as strong as CASSIOPeiA's own typical figure, and its designers...CLM-0687The Chinese design says how it gets to orbit. Rockets carry the parts to a low orbit. A reusable space tug then moves each part up to the...CLM-0688The Chinese design shields the satellite parts from radiation during the climb to high orbit, using the tug itself as the shield. It also...CLM-0689The Chinese team published its own cost figures for a one-gigawatt system: about 17.3 billion US dollars over 30 years, which they put at...CLM-0692The Chinese design's own summary table adds up: the parts weigh what the total says they weigh. Its claimed 12.3 per cent efficiency is...CLM-0697The Chinese 6.6 cent figure ignores the cost of money. Once you charge interest on the capital, the same numbers give about 10 cents at a...More on the source page.