With current battery and hydro storage prices, their cheaper than natural gas with with the cost of the buffer, and absurdly cheap for any industrial application that doesn’t.
Also there are bulk industrial processes to make steel, concrete, fertilizer, and glass with little to no carbon emissions, they just require more electricity and so aren’t cost effective if your electricity comes from fossil fuels, hence why most such plants only started construction once the cost for electricity in general dropped below the cost for fossil electricity.
Moreover while mining and shipping are only starting decarbonization, the required fossil fuel extraction is already far, far smaller than what’s continually required to run the generation they are replacing, and that’s only going to continue to drop as more and more primary energy is electrified with renewables.
I just installed a sol ark system, and can confirm that they work just as well with a pi and Solar Assistant. Not open source, but integrates well with homeassistant and no need for network connecting the actual electrical equipment, just usb.