This is one of those areas where an technology neutral law should be applied. Rather than have the government pay for insurance, move that to a tax on the consumer based on how much energy is consumed and the cost of accidents and environmental impact. For energy produced by fossil fuels that would be any costs associated with global warming (including any accidents and extreme weather), for hydro it would be flooding, and for nuclear it would be nuclear accidents. Base the insurance cost on the historical accident rate and the predicted rate in the future.

That would make renewable energy even cheaper in optimal weather, energy produced from fossil fuel a few order of magnitudes more expensive for every watt consumed, and nuclear and hydro would increase by a modest sum.