I can't offer a citation, but I can observe that electricity prices in wholesale markets regularly go negative during times when renewables are operating at peak output. Since people overprovision solar to have enough power at non-peak times, during peak generation times, there's too much energy.

This doesn't happen with fossil fuels, since the plant operator will of course reduce output as far as possible by reducing fuel consumption.

So it seems entirely reasonable that the bulk of bitcoin mining in the future is going to be done at times when the electricity price is exceptionally low (or negative), and mostly be powered by renewables. It's an economically rational thing to do and as a bonus it will provide some grid stability.