Rankine cycle efficiency can be up to 45%; monocrystalline solar panels ~25%? I suppose you aren't paying for the sunshine, but if cloudy days affected coal power, James Watt wouldn't be famous.

Luckily solar panels work for 30+ years while coal works for only as long as you burn it. You can also recycle solar panels, but try reversing entropy to get your coal back and you’ll see what’s up. Cloudy days are solved by wind, ocean energy, geothermal, storage, etc.

"Cloudy days are solved by wind, ocean energy, geothermal, storage,"

Or, as Homer Simpson famously put it..."I dunno; Internet?"

But seriously, there's no significant recycling of solar panels, coal extraction is a known process, and good luck running an industrial economy exclusively on renewables.

> storage

There’s the direct answer to your question, cost of installed grid battery storage are getting cheaper by the user and it’s completely viable option at present. It’s not some vague fantasy idea like power plants in space or something, just look at California’s energy mix during peaks that in just a few years has become dominated by solar+batteries.

For longer periods of low-sun in a climate like Ireland see the other renewable options he mentioned. Plus a couple natural gas plants for fallback that can comfortably sit idle until needed.

If some combo of renewables are used 90% of the time when possible, no one is going to be mad about modern clean-burning LNG plants compared to a toxic, expensive relic of the past like coal.

Current trends make it clear the future will be renewables, grid battery storage, and however many natural gas plants are needed for reliability based on local climate (plus keeping nuclear online if you already have it). And that “future” is pretty much here already in places like California.

I wonder how cheap one would have to make electricity to make up for CA's silly regulatory environment and confiscatory taxes.

Places like California, which is right up there w/ Tunisia as the best-case scenario for solar, will have so much surplus electricity that USX and Tata are rushing to build steel mills there to take advantage.

Any day now, for sure.

If you're going to make that comparison, you need to compare apples-to-apples and include solar efficiency in the coal too. After all coal's energy originally came from the sun. Plants converted the sunlight into energy at an efficiency of about 1%. A miniscule fraction of that energy went into the plant growth, and then a miniscule fraction of that energy was captured when the plant was converted into coal.