As you say, it is not practicable to use solar for major loads at present, but there is some progress.
Catepillar have an electric excavator: https://electrek.co/2019/01/29/caterpillar-electric-excavator-giant-battery-pack/ Much too small for mining, but a step in the right direction. For continuous operation, 2 or 3 interchangeable batteries could be used.
Large power needs large solar collectors. Average insolation is 1.36 kW per sq m. https://earthobservatory.nasa.gov/features/EnergyBalance/page2.php So at 70% efficiency, that is about 1 kW/m2. For each MW, that's 1000 m2. For 24 hrs, need about 3 * 1 kW/m2 -> 3000 m2, plus battery storage for about 12 to 15 hrs, say 15 MWhrs.
The VSun CellCube is discussed in this link: http://vsunenergy.com.au/wp-content/uploads/2016/11/Utility-Flyer.pdf
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