It still has the same problem that you can't "turn them up" to cope with higher demand over longish periods, which makes dealing with them tricky. They are a good step though.
As someone who lives in a country where half the year it's -10℃ with 2 hours of sunlight (zero hours if it's cloudy), I'd have to say it's not quite viable.
Most of the world's population is in more sunny areas.