Value chain · CLM-1115
In plain terms
Mirrors that doubled the light only added 40 per cent to the output, because the cells ran hot and the mirrors were not flat; after thirty years of radiation the array was down to 59 per cent of where it started, and the mirrors helped even less.
The claim as recorded
For the 1977 silicon array at geometric concentration ratio 2, Boeing's Table 3.2-3 gives beginning-of-life output of 188.8 W/m2 at 1 sun direct (55 C), less 38.5 for the 106 C temperature at CR 2, plus 128.5 from reflected sun, less 13.9 for a 5 per cent reflector flatness loss, a net reflector increment of 76.1 and an integrated 264.9 W/m2, an "Effective CR" (integrated output over 1 sun direct output) of 1.40 and "Efficiency = 9.55%"; Table 3.2-5 at 30 years gives 119.1 W/m2 at 1 sun, less 15.7 (89 C), plus 61.8, less 9.1, net 37.0, integrated 156.1 W/m2, effective CR 1.31 and 5.6 per cent, with Figure 3.2-6 marking "59% @ 30 YEARS"; so the reflectors that double the geometric area add 40 per cent at the start and 31 per cent at the end, and the array loses 41 per cent of its output over the design life.
Evidence behind this: T3-contractor performance chain at beginning and end of life, every line printed and every sum reproducible.
Scope and limits
THE EFFICIENCY DENOMINATOR IS NOT PRINTED: 9.55 and 5.6 per cent imply a collecting area 2.05 times the blanket, and the record states that rather than repairing it. 1977 CR 2 design, dropped in favour of CR 1 (CLM-1117). The 30-year values rest on the extrapolated 63.1 per cent cell retention (CLM-1116).
What it assumes
1353 W/m2 solar constant; the 5 per cent flatness factor and the 55, 106 and 89 C temperatures as stated.
Where it comes from
PDF 43 / printed 37, render read: "Array specific output at 1 sun/direct illumination (55 C) 188.8 W/m2"; "Array temperature degradation at CR = 2 (106 C) -38.5 W/m2*"; "Array specific output (106 C) from reflected sun -128.5 W/m2*" (the sign on the render is a leading dash before a positive increment); "Reflector flatness factor 5% -13.9 W/m2"; "Net output increment due to reflectors 76.1 W/m2"; "Integrated specific output 264.9 W/m2"; "Effective CR = integrated output / 1 sun direct output = 1.40"; "Efficiency = 9.55%"; "* Items subject to degradation". PDF 48 / printed 44, render read: "119.1 W/m2", "-15.7 W/m2*", "+61.8 W/m2*", "-9.1 W/m2", "37.0 W/m2", "156.1 W/m2", "= 1.31", "= 5.6%"; Figure 3.2-6 "INITIAL SPECIFIC OUTPUT = 264.9 W/M2 EFFICIENCY = 9.55%" and "59% @ 30 YEARS". Recomputed: 128.5 - 38.5 - 13.9 = 76.1; 188.8 + 76.1 = 264.9; 264.9 / 188.8 = 1.403; 61.8 - 15.7 - 9.1 = 37.0; 119.1 + 37.0 = 156.1; 156.1 / 119.1 = 1.311; 156.1 / 264.9 = 0.589; 119.1 / 188.8 = 0.631, the cell retention of CLM-1116. On efficiency: 264.9 / (2 x 1353) = 9.79 per cent and 156.1 / (2 x 1353) = 5.77, not the printed 9.55 and 5.6; both printed values reproduce on 2,774 W/m2 of collecting-area insolation per m2 of blanket (264.9 / 0.0955 = 2,774; 156.1 / 0.056 = 2,788), i.e. a collecting area 2.05 times the blanket, consistent with the text's reflectors "oversized to fully illuminate cells when misoriented" (PDF 40, render reading) but not tabulated.
Basis: W/m2 of blanket; effective concentration ratio; per cent of collecting area
Related records
- Answers question
- QST-018 not published in this release
Cite this
energyaperture.com/c/clm-1115
CLM-1115, Energy Aperture, as of 1977-07.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-475
- CLM-1114The 1977 silicon design assumed an 18 per cent cell that did not yet exist, doubled the sunlight on it with cheap plastic mirrors, and got...CLM-1116Thirty years of radiation behind a hair-thin glass cover was expected to take a third of the cell's power; a cover three times thicker...CLM-1117The 1977 study found the cheapest way to keep a silicon satellite at full power was to heal the radiation damage in place rather than build...CLM-1118In 1977 five radiation-damaged cells were healed with a laser or an electron gun, getting back between a fifth and a half of what they had...CLM-1120In 1977 the gallium arsenide option rested on a 20 per cent cell nobody had made, an assumption that it would still be near 20 per cent...CLM-1121Half a kilogram per square metre for the working blanket, about half of it the silicon itself; per kilowatt delivered on the ground the...CLM-1468The basic idea, a solar power satellite climbing to its final orbit on electric engines run by solar panels it carries, with no separate...