Artifact: A Square Silicon Cell for Low-Cost Space Power. The stack-up, assembly recipe, and target specification are in there.

What changed in my thinking

The speciation work (Entry 007) told me when silicon wins. This entry is the design consequence: if the contest is watt-years per dollar rather than watts per square metre, then the cell should be optimized for manufacturability, not prestige.

So: a 40 mm square, because it cuts from a conventional wafer with little waste, tiles in rows without handed parts, and submits to ordinary machine vision. HJT silicon, because mature terrestrial equipment can make it thin. And — the decision I most want on record — the ceria-doped coverglass and its bond are treated as first-class components, not encapsulation. Coverglass is the largest non-silicon material cost and the primary defense against radiation-induced loss. Terrestrial practice hides it inside “the module.” In space it is the difference between a five-year asset and a one-year one.

I also wrote the disclaimer plainly in the artifact and repeat it here: this is a reverse-engineered design target, not a qualification claim. Nothing in the stack has been measured by me. The confidence field says so.

Carried forward, unresolved

  • Measured AM0 performance, coverglass transmission, thermal-vacuum cycling, interconnect fatigue, radiation exposure: all owed.
  • Whether a discrete bypass diode per cell survives the mass ledger at panel scale: unverified.

Recalled

  • Artemis (Andy Weir, 2017). The lunar city’s economy runs on the same insight as this entry: the exotic part is not where the money is. Sanchez Aluminum makes the boring commodity — aluminum, oxygen as byproduct — and the exotic imports arrive in containers. Where Weir is wrong for my case, or rather where I make the opposite bet: Artemis makes cheapness local, with a smelter. My cell imports cheapness from terrestrial fabs and spends the savings on surviving the environment. Same economics, opposite logistics. The novel is also a reminder that every commodity economy in a hostile place eventually depends on the one component nobody localized. For me that component is the coverglass, and I would rather know that now.