I don't think anyone is predicting that installation curves will continue to accelerate. There are physical and financial limits. As the annual installation amounts reach practical limits acceleration will slow and most likely settle into somewhat constant year to year installation amounts.
I actually expect worldwide installation rates to continue to accelerate for five or more years. Installations are starting to occur in more and more countries. Some haven't really gotten started yet.
Perhaps you don't understand what has happened to the cost of renewables.
If one wants to add capacity to the grid there is no cheaper way to do that than building a wind farm. Natural gas is a slight bit cheaper but prices are artificially low (in the US) and rising. No one (except those who hype the gas business) is predicting natural gas to remain as cheap as it is now. If fact, the price of gas is up more than 30% from its low of June, 2012. The EIA is predicting that gas will rise to a level in 2014 which will cause a small increase in coal use.
If one wants to bring more peak hour capacity on the grid solar has become a major choice. The price of solar is cheaper than running a gas peaker and installing solar locks in the price of electricity for 3-4 decades.
This is not government money. This is utility company money. Government money has pretty much played the role it needed to play. Like many emerging technologies, prices are quite high at first until the technology begins to mature, efficiencies discovered, and economies of scale kick in.
US subsidies for residential solar are designed to scale back. They are based on a percentage of system costs. They cut the cost by 30%. There's a point at which the 30% discount will not be necessary to make putting solar on your roof cheaper than buying electricity from the grid.
Right now rooftop solar is being installed in Germany and Australia for $2/watt. No subsidies, no government money.
Solar on ones roof in Southern California at $2/watt and financed at 5% generates electricity for about 8 cents per kWh. The average cost of electricity in SoCal is something like 18 cents per kWh. No government money is needed to make that math work.
The UK just installed a large solar array for $1.60/watt. A large array in SoCal installed at $1.60/watt and financed at 5% would mean that the utility could lock in electricity at 6.5 cents per kWh for the next 20 years. And for another 10 to 20+ years they would get electricity to sell for the cost of about 0 cents per kWh. Right now they may be paying over 30 cents per kWh for peak hour supply.
You can't build a new coal or nuclear plant and produce electricity for even 10 cents per kWh, try 15+. If a utility needs more capacity then what makes sense is a mix of wind and solar then to use your existing gas and hydro to fill in around.
Then, there's something else happening, I think. I think the world's governments have decided that they must do something to curtail climate change. When you have China rushing to the front of the parade to help lead it you know things have changed.
I don't know how people think in the UK. Here in the US we value having solar on houses. A rather large scale study found that people paid more for a house with solar installed. In fact, the premium they paid often exceeded the cost of the system.
"All those homeowners who have been installing residential solar panels over the last decade may find it was a more practical decision than they thought. The electricity generated may have cost more than that coming from the local power company (half of which, nationwide, comes from burning coal), but if they choose to sell their homes, the price premium they will get for the solar system should let them recoup much of their original capital investment.
That is the conclusion of three researchers at the Lawrence Berkeley National Laboratory, who looked at home sales — both homes with photovoltaic systems and homes without — in California over an eight-and-a-half-year period ending in mid-2009. The abstract of their study states, “the analysis finds strong evidence that California homes with PV systems have sold for a premium over comparable homes without PV systems.”
The premium ranged from $3.90 to $6.40 per watt of capacity, but tended most often to be about $5.50 per watt. This, the study said, “corresponds to a home sales price premium of approximately $17,000 for a relatively new 3,100-watt PV system (the average size of PV systems in the study).”
And the bottom line: “These average sales price premiums appear to be comparable to the investment that homeowners have made to install PV systems in California, which from 2001 through 2009 averaged approximately $5/watt.”http://green.blogs.nytimes.com/2011/04/21/study-finds-solar-panels-increase-home-values/