I don't know if I agree with the GP, but the existence of the energy is all but irrelevant. You almost might as well quote the amount of power the sun produces

I don't know if I agree with the GP, but the existence of the energy is all but irrelevant. You almost might as well quote the amount of power the sun produces from fusion, the amount of wind, the amount of uranium, whatever. For everyone to have a hot shower, you need indoor plumbing, clean water, water heater, etc, all of which implies a standard of living which I think is the point. While there might be a weak rebuttal about outdoor showers, that would be "begging the question" - the point is that equality in standard of living is not possible (not agreeing or disagreeing, just pointing out that incident solar energy on the earth is irrelevant)