What would make it clear whether solar + battery at this proportion is a viable source of baseload power is output volatility figures for a few years of operation (though one year would probably give a reasonable indication).

Tangent: The industry has a metric, availability factor, to describe what proportion of the time a plant can supply energy - but conventionally it only considers maintenance-related downtime and ignores periods where no energy is produced because of lack of 'fuel', giving figures of 99 and 100% availability for wind and solar respectively. That needs to change if we're going to measure whether renewables can provide suitable baseload power. The alternative, capacity factor, doesn't ignore periods of no generation in the same way, but it penalises dispatchable sources for having excess capacity so it's not great either.