CALC-133

The Royal Society 2050 range in 2024 pounds, beside the restated space solar estimates

REGISTERED 2026-10-13. Drafted for QST-021, checked by a second reader (10 PASS, 8 FIX, all applied before landing), landed by SBSP-coord. The commit that landed it names the draft and the check. Script: qst021-bar-restate.py. verified: VER-2358 CONFIRMED 2026-10-14 (also VER-2334 CONFIRMED 2026-10-14 (also VER-2333 CONFIRMED 2026-10-13)).

Feeds figure H of the QST-021 answer and article, and the sentences that compare the estimates with the British bar. Answers QST-021. Basis: GBP2024/MWh. Space solar figures at 20-year life, 3 and 10 per cent real (CALC-062, CALC-063). Royal Society figures at its own 5 to 10 per cent range.

Script. qst021-bar-restate.py, run with python -I.

Why it was needed. The Royal Society prices a whole British wind, solar and hydrogen system in 2021 pounds (CLM-1419). The space solar estimates are restated in 2024 pounds (CALC-062, CALC-063). Setting one against the other needs one price year.

Inputs.

Working, transcribed.

multiplier 2021 to 2024 = 96.5672 / 82.7095 = 1.1675 Royal Society system 52 -> 60.7 92 -> 107.4 GBP2024/MWh wind and solar input 30 -> 35.0 45 -> 52.5

at 10 per cent real, against the Royal Society 10 per cent end (107.4): Frazer-Nash BEIS fifth unit 36.8 0.34 x Frazer-Nash BEIS first unit 49.1 0.46 x Frazer-Nash ESA first unit p10 56.6 0.53 x Frazer-Nash ESA first unit p90 110.1 1.03 x NASA RD1 rebuilt baseline 930.3 8.66 x NASA RD2 rebuilt baseline 1,791.1 16.67 x NASA RD1 combined improvements 57.9 0.54 x NASA RD2 combined improvements 154.4 1.44 x

Result: the British bar is GBP 60.7 to 107.4 per MWh in 2024 pounds. At 10 per cent real, the UK study's first unit is 0.46 times its top end and NASA's rebuilt mirror design 8.66 times.

What the comparison is. A plant's cost per unit for a space solar design, set against the cost per unit of demand met by a whole reliable wind, solar and hydrogen system. The designs are assumed to run for between 60 and 100 per cent of the year: all of it in the BEIS study's model (SRC-019 p.3), 95 to 98.5 per cent in the ESA study (CLM-0280), 99.7 per cent for NASA's mirror design and 60 per cent for its flat-panel design (CLM-1349, CLM-0286). It treats space solar as needing no backup. Its own eclipses, maintenance and grid costs are not added, so the space solar side is a floor on its system cost, not an estimate of it.

Where this fails. - Two deflators. CALC-063 moved Frazer-Nash BEIS from 2018 to 2024 with a UK CPI multiplier of 1.2658 that was recalled when CALC-060 was written (CLM-0390 limits). This record moves the Royal Society figures with the fetched GDP deflator for 2021 to 2024. The GDP deflator's 2018 to 2024 multiplier is 1.2634 (96.5672 / 76.4375), 0.19 per cent below the recalled CPI one; fetched ONS CPI (SRC-774) gives 1.2644 (133.9 / 105.9), 0.11 per cent below it. That bounds the mixed-deflator effect for the Frazer-Nash BEIS rows only. The Frazer-Nash ESA and NASA rows rest on euro-area HICP, US CPI and exchange rates recalled in CALC-060. Held series now exist (SRC-772, SRC-775, SRC-777, ECB file; CALC-124 uses them) and each recalled factor differs from them by 0.11 per cent or less (reviewer check, 2026-10-13), so no multiple above moves by more than that from this cause. - Discount rates. The Royal Society's 52 pairs low costs with 5 per cent and its 92 pairs high costs with 10 per cent; neither printed end isolates the rate. The 10 per cent comparison above sets the space solar figures at 10 per cent against the high-cost end, where the bar is at its highest. The report does not say whether its 5 and 10 per cent are real or nominal (CLM-1419 basis); the space solar figures are at real rates. Figure 24 (p.64) plots 10 per cent results for each supply cost; read from the chart, the lowest 10 per cent dot is about GBP 57/MWh in 2021 prices (about 66 in 2024 prices) against 92 (107.4) at the high end. Against 66 every multiple above is about 1.6 times larger. A chart reading, not a printed figure. - Life. Space solar figures are at a 20-year life chosen by the restatement (CALC-062, CALC-063); the Royal Society's asset lives are its own. Not harmonised. - Scope. The Royal Society figure is a modelled Great Britain system for 2050 that leaves out waste and biomass burning, hydropower, interconnectors and grid location effects, with wind and solar supply about 1.33 times demand (CLM-1419 limits and assumes). The space solar figures are plant costs from Frazer-Nash's studies for BEIS (2021) and ESA (2022) and NASA's study (2024), for no particular grid and not for one common year (the BEIS study puts both its first unit, SRC-021 PDF p.14, and its costed fifth unit, CLM-0170, at 2040; NASA's designs run from 2050, CLM-0662), and are rebuilds or shortcuts with their own limits (CALC-061: plus or minus 25 to 30 per cent for the shortcut). The two NASA "combined improvements" rows are NASA's own stated best case, stacking five or six improvements (the report's own lists differ; CLM-0124), and are not a forecast (CLM-0374 (low confidence) limits).

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