Value chain · CLM-0210
In plain terms
A 1978 US government design for a solar power satellite planned to move its power around at 40,000 volts DC because it judged that this would save weight compared with AC, but the same report lists the high-voltage DC switches and cable insulation needed to do this as still to be developed.
The claim as recorded
The 1978 DOE/NASA 5 GW SPS reference design assumes 40 kV DC for power transmission from the solar array to the microwave antenna, chosen over AC on power-conductor and conditioning-equipment mass grounds, while the report's own technology-needs list states that 40 to 50 kV DC switchgear and cable insulation still required development.
Scope and limits
This is a 1978 paper design choice, not an achieved or flight-proven power-distribution architecture. It does not establish that 40-50 kV DC switchgear exists today, nor does it transfer to any specific present-day SBSP concept without re-verification against that concept's own bus-voltage choice.
What it assumes
The mass-based preference for DC over AC continues to hold as satellite scale, materials and power-processing technology change; the two page references describe the same 1978 point design, not independent corroboration.
Where it comes from
p.121 (Appendix A): "AC vs. DC Transmission - DC transmission at 40 kV is preferred based on power conductor and conditioning equipment mass considerations." p.92 (Appendix, technology needs, item 3 "Power Distribution"): "High voltage (40 to 50 kv) DC switchgear development." and "High voltage (40 to 50 kv) electrical cable insulation development." Both phrases confirmed verbatim against the PDF text layer.
Basis: 5 GW GEO photovoltaic point design, DOE/NASA SPS Reference System Report
Related records
- Answers question
- QST-002 not published in this release
Cite this
energyaperture.com/c/clm-0210
CLM-0210, Energy Aperture, as of 1978.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-085
- CLM-0013The paper that modern UK studies rely on for the beam figure calls anything below 1 kilowatt per square metre safe, with 230 watts per...CLM-0020The original 1978 design set the beam at 230 watts per square metre in the middle of the receiving site, about one twenty-third of that at...CLM-0023In the 1978 reference design, two limits set the size of the transmitter and the receiving site: how much heat the transmitter can shed...CLM-0039The 1978 report set the figure to protect radio and navigation systems from a disturbed ionosphere, called the number theoretical and...CLM-0045The apparent conflict between 12 and 23 was not an error. The underlying study gave a range, and the figure adopted sits near the top of it.CLM-0101The 1978 contract required the researchers to report fixes if ionospheric disturbance pushed the pilot-beam phase error past 2 to 3...CLM-0137In four major space solar power studies from 1978 to 2007, none put a number on how much of the beam's energy would be lost if the beam...CLM-0138The original 1978 government design for beaming power down from space adds up all the expected energy losses to get 63% overall efficiency...More on the source page.