It’s clear that solar and battery storage can now provide affordable base load power, and can be deployed rapidly (this project is set to turn up in 2022).
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.
Like it or not tacking on the cost of climate change to power generation is so far from current reality that adding that hypothetical constraint is meaningless. The people making these decisions have real tangible costs that matter right now that they will prioritize in their comparison.
On the flipside, appliances (water heating, fridges, cold-rooms, space-heaters,e tc.) should be encouraged to talk back to the suppliers APIs to indicate likely near-future demand, current constraints and demands and so on, so informing the 'grid' with demand data at micro-scale.
I guess this is something like what people might mean when they speak of making the grid 'more intelligent'...
Guess that's the power of political donations