Who is installing renewable energy the fastest?

You may be interested in this, if you have not yet seen it. It was published in 2012. A few excerpts:

In 2000, IEA projected that there would be 30 gigawatts of wind power worldwide by 2010, but the estimate was off by a factor of 7. Wind power produced 200 gigawatts in 2010, an investment of approximately $400 billion.

In 2000, IEA estimated that China would have 2 gigawatts of wind power installed by 2010. China reached 45 gigawatts by the end of 2010. The IEA projected that China wind power in 2020 would be 3.7 gigawatts, but most projections now exceed 150 gigawatts, or 40 times more.

In 2002, a top industry analyst predicted an additional 1 gigawatt (solar) annual market by 2010. The annual market in 2010 was 17 times that at 17 gigawatts.

What do cell phones, energy efficiency, and renewable energy have in common? One, they are dynamic areas of technology development and market competition, which makes straight-line projections pretty useless. And two, they are distributed, with millions of loosely networked people and organizations working on them in parallel. Distributed, human-scale technologies come in small increments. They replicate quickly, so there’s more variation and competitive selection, and thus more evolution.

Nuclear power, in contrast, comes in gigantic increments only (at least for now). There’s a limited number of people doing the R&D, a limited number of entities capable of building or financing the power plants. It’s a little easier to know the potential.

When it comes to complex, parallel, loosely linked networks, the dynamics are more fluid and nonlinear changes more likely. They’re harder to quantify and predict. And so we consistently underestimate them. Something to keep in mind when pondering what today’s projections are going to look like in 2020.

Paul Krugman referred to the above in an editorial today.  He concludes:

So we couldn’t have counted on renewable energy getting so cheap so fast. But it did. Claims by conservatives that policies to reduce emissions would kill the economy never made much sense, but anyone making those claims now is living in a time warp, ignoring the way the energy landscape has changed.

Makes me want to stick around to see what 2030 brings.  

I'd say further-- you can't separate the issue of politics and costs. Falling renewable costs make it easier for more politicians to back it as a common sense solution, while in areas where the cost difference isn't dramatic you're going to be less likely to see politicians willing to plant the renewable flag

Three quarters of the global population lives in the sunbelt (+/- 35 deg of latitude) where there is high and consistent solar availability and no cold winters. 

This is a great data point-- do you have a citation for this? I'd love to keep it handy!

You're certainly correct that PV is a poor choice at high latitudes, where winter sun is lacking.  But that's not the only problem for PV.

Night-time hurts PV also, and the resulting need for batteries drives up cost, and creates more challenges with environmentally friendly production and disposal of the equipment. (And enforcement of environmental regulations is always difficult in developing nations.)

The dilute nature of solar energy means that PV systems will always result in a large environmental footprint for populations that rely on them.

And clouds are a severe hindrance because they result in PV systems being unreliable.  Clouds are a feature anywhere growing crops is viable; all large historical human settlements are located near food sources (California is an anomaly caused by the gold rush and fledgling film industry which depended on natural lighting).  Batteries may help with nightly outages that last for hours, mostly while demand is low, but batteries can't smooth out weather variations, which can last days.

Because of the inherent unreliability, PV and windpower systems will always be dependent on firm backup generation.  The offered green hydrogen solution is not suitable, since green hydrogen must cost more than the electricity from which it is made, whereas fossil fuel costs less than the electricity it is used to produce.

The need for a separate parallel fossil fuel system, and the fact that fossil fuel has fallen in cost over time, mean that PV and windpower are not really leading us away from fossil fuel, but are simply shifting the balance somewhat.

True enough.  I see your point.