Value chain · CLM-1274
In plain terms
NASA said its programme had built a test solar panel that it expected to lead to arrays more than three times lighter per watt than the best of the day, kept its power beams to about a tenth of midday sunlight for safety, and found that the very high voltages assumed in 1979 would not work in space.
The claim as recorded
NASA reported to Congress in September 2000 that SERT had demonstrated, at panel level in a test chamber, a linear Fresnel-lens concentrator solar array with sunlight-to-voltage efficiency of almost 30 per cent (about 375 W/m2) and more than 375 W/kg, which it expected to give about 170 W/kg at array level, against about 45 W/kg for the then state-of-the-art array. It reported that, for beam safety, "center-of-beam" intensities in SERT were limited to about 100-200 W/m2 for both microwave and visible-light transmission, which it equated to 10-20 per cent of noon summer sunlight. It also reported SERT's finding that the 1979 Reference System's very high array voltages (about 40,000 V) were not technically feasible because of interactions with the space environment, so lower voltages must be used.
Evidence behind this: The agency's own summary of its programme's technical results to Congress; the underlying test reports are not held.
Scope and limits
SUMMARY CLAIMS, TEST REPORTS NOT HELD. The panel was tested in a chamber, not in orbit. The 170 W/kg is a projection for an array, not a measurement. The 100-200 W/m2 limit is SERT's design choice, not a regulatory limit. The 2001 NRC review (CLM-0922) found no comprehensive PV array trade study had been done for SSP. The 10-20 per cent of sunlight equivalence implies about 1,000 W/m2 noon sunlight at the ground, as the page frames it.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
PDF p.2 (transcript): Fresnel concentrator array demonstrated at panel level, efficiency almost 30% (about 375 watts/m2), greater than 375 watts/kilogram, about 170 watts/kilogram in application against about 45 watts/kilogram state of the art (paraphrase). Beam safety: "center-of-beam" intensities limited to the general range of 100-200 watts/m2, 10-20% of normal noon summer sunlight (paraphrase beyond the span). PMAD: 1979 presumption of very high array voltages (e.g. 40,000 volts) found not technically feasible; lower voltages must be used (paraphrase). Arithmetic check (drafter's): 170 / 45 = 3.8, consistent with "better than three-fold"; 375 W/m2 / 1,361 W/m2 = 27.6 per cent, consistent with "almost 30%" only if the test illumination was near 1,300 W/m2 (not stated).
Basis: per cent sunlight-to-voltage efficiency; W/m2; W/kg (panel and projected array level); W/m2 beam centre; volts
Related records
- Answers question
- QST-001 not published in this releaseQST-018 not published in this releaseQST-043 not published in this release
Cite this
energyaperture.com/c/clm-1274
CLM-1274, Energy Aperture, as of 2000-09-07.
Connected records
Other published records linked to this one. A list, not a judgement.