What I mean by scale is scale of production (units per year). Solar wasn’t even close to economical when the first nuclear reactors were coming online. Solar became viable over many decades of production, technological improvement, and supply chain development.

Solar panel costs have fallen 3 orders of magnitude since the 1970s [1]. SMRs wouldn’t need that dramatic of a production cost improvement to become viable for commercial energy production. The main barrier remains regulatory.

[1] https://ourworldindata.org/data-insights/solar-panel-prices-...