Value chain · CLM-0975
In plain terms
Depending on which published assumptions you take, a satellite needs between about 2 and 6 square kilometres of solar blanket for every gigawatt it generates. Nearly all of that spread comes from how efficient the cells are; degradation and pointing each shift it by ten per cent or so, and the exact sunlight value by under one per cent.
The claim as recorded
Across the register's held ranges - cell efficiency 0.173 to 0.37, end-of-life degradation 0.85 to 0.98, pointing and seasonal factor 0.88 to 0.97, solar constant 1353 to 1361 W/m2 (a summer-solstice intensity such as Rockwell's 1311.5 W/m2 already holds the solstice reduction that the 0.88 factor carries) - the solar blanket area per gigawatt of DC at the array spans 2.3 to 6.3 km2, and cell efficiency is the only factor that moves it by more than about 15 per cent.
Evidence behind this: T0-derivation over held ranges; the upper cell efficiencies are modelled or assumed, not achieved.
Scope and limits
MEDIUM BECAUSE THE UPPER CELL EFFICIENCIES ARE MODELLED (CLM-0200) OR ASSUMED BY DESIGN STUDIES (CLM-0201) RATHER THAN ACHIEVED. SRC-171's 0.85 to 0.98 is degradation during electric orbit raising before service, not 30-year GEO life, and SRC-085's 30-year factors assume annealing; the sweep uses each as stated and they are different quantities. Per gigawatt at the busbar the figures are about 1.8 times larger, so a figure quoted "per GW" without saying array or busbar is ambiguous by that factor.
What it assumes
f_temp and f_design are held at SRC-085's silicon values (0.954, 0.951) through the sweep. The band is blanket area at CR = 1; concentrating designs need reflector area too.
Where it comes from
This is the project's own working, shown in full:
A = P / (S x CR x eta x f_temp x f_design x f_rad x f_pointing). Band ends: 1353 x 0.173 x 0.85 x 0.880 x 0.954 x 0.951 = 159 W/m2, 6.30 km2/GW; 1361 x 0.37 x 0.98 x 0.968 x 0.954 x 0.951 = 433 W/m2, 2.31 km2/GW. Anchors: SRC-085 Si 52.34 / 9.07 = 5.77; SRC-085 GaAlAs 26.52 / 9.08 = 2.92 of blanket; Rockwell 27 / 9.52 = 2.84. Elasticities, each factor in the denominator: cell 0.173 / 0.37 = 0.47; degradation 0.85 / 0.98 = 0.87; pointing 0.880 / 0.968 = 0.91; solar constant 1353 / 1361 = 0.994. Rockwell's 1311.5 W/m2 is one of its "summer solstice values" (SRC-449 p.268) and is paired only with its own seasonal 0.968, never with the 0.880 that holds SRC-085's 0.9675 solstice factor. CLM-0692's CAST 6 km2 per GW delivered becomes about 3.3 per GW at the array once SRC-085's 0.551 downstream chain is applied. SRC-171 p.8: "the remaining power increases from 85% to 92% to 95%" and "(94% to 97% to 98%)" by coverglass thickness and trajectory.
Basis: km2 of blanket per GW of DC at the array, end of life, CR = 1
Related records
- Answers question
- QST-018 not published in this release
Cite this
energyaperture.com/c/clm-0975
CLM-0975, Energy Aperture, as of 2026-09-17.
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.
- Also from SRC-171
- CLM-0676A peer-reviewed study calculates that solar panels lose a real, measurable amount of power, up to about 15% in the worst case tested, just...
- Also from SRC-449
- CLM-0964To build two of these satellites a year, about 300 tonnes of material had to arrive at the orbital construction site every day. Getting it...CLM-0974The 1978 reference design shows every loss between sunlight and the power grid as a chain of numbered boxes, and the boxes multiply out...CLM-1058The often-repeated claim that the magnetron is 188 decibels quieter than its carrier traces to a conference abstract in which the tube...CLM-1059By spring 1980 the engineers, the reviewing panel and the ionosphere experimenters were all saying the beam-intensity ceiling the whole...CLM-1060The 1980 review did not agree with itself on how much of a satellite's cost was rockets: one paper said over a third, the programme's own...CLM-1061In one 1980 volume the satellite cost anywhere from about 2,300 to 3,800 dollars a kilowatt depending on who added what - and the programme...CLM-1062In 1980 the launch vehicle that everything was costed on was said by its own designers to be arbitrarily big, and they proposed a rocket a...CLM-1063In 1980 the magnetron satellite was the lightest per kilowatt on paper and the most efficient tube on the bench, the klystron was the...More on the source page.