Speaker
Description
The admissible concentration of passively cooled low-concentration photovoltaics (LCPV) is usually set by the hottest hour of the year, often against the 85 °C of qualification cycling — a test temperature, not an operating limit. IEC TS 63126 judges thermal durability instead on T98, the temperature exceeded 175 h per year, but was written for flat modules.
We apply it, to our knowledge for the first time, to a concentrating receiver: a two-wing EUCLIDES-type trough (10x geometric, 9.02x effective) carrying eight series-connected silicon cells with resized metallisation and a passive finned heat sink, simulated over the 8760 h of a PVGIS typical year at Ouagadougou (12.37° N), nights included. Sub-models are validated block by block: dVoc/dT within 1.5 % of Coventry (2004) at 30 suns, cell temperature within 3.26 K RMSE of Algareu (2017) at matched irradiance, ambient and wind.
Durability (T98 ≤ 70 °C) limits concentration to 6.1x, whereas the worst-hour criterion at 85 °C would admit 7.4x — 21 % too much. The worst-hour-to-T98 gap grows with concentration, from 4.7 K at 1.1x to 20.8 K at 16x, outside the 6–12 K reported for flat modules at both ends: the two criteria are not interchangeable. At the 10x design point, T98 reaches 83.6 °C for the mean cell and 109.6 °C at the line-focus hot spot, which misses the 70 °C level even at 4x. Compliance costs 32 % of annual energy but saves 39 % of mirror; IEC level 1 (80 °C) admits 8.9x for a 7.8 % loss. A receiver Ross coefficient (32.8–64.4 mK·m²/W) makes published global T98 maps usable for concentrators.
The heat sink is unmeasured, and transferring a flat-module criterion to a concentrator is declared, not validated.