The Trina assessment is realistic, given the need for module manufacturers to restore some profitability. Until this happens they will be unable to attract investment in any significant new more efficient capacity. Long periods of price stability have been a feature of the PV module business. The most recent was the 2000 to 2008 period annotated as "Silicon Feedstock Supply" when a cartel kept polysilicon prices stable at around $400/kg and made huge profits. Polysilicon is now under $20/kg.
There are still optimistic PV module price reduction forecasts from Bloomberg, Citibank and PV analysts like NPD Solarbuzz and EPRI, but there seems to be no basis for these assessments other than projecting short term trends foreword without regard for underlying industry fundamentals. Manufacturing costs are continuing to slowly reduce, but the benefits will go to restoring realistic margins from today's unsustainable zero margins. This margin restoration is being enabled by the restoration of a balance between supply and demand as companies like Suntech go under and the Chinese government has stepped in to back stop the industry and cover for the massive reduction in European demand.
System costs have room to reduce, especially in residential and commercial markets where soft costs are high. Utility scale PV in the US is below $2/Wp, but with modules firming up at around $0.70/Wp, total utility system costs won't make it below $1.50/Wp for a long time. This is still not competitive without subsidy in the sunniest markets. This means that the market size will still be determined by the scale of subsidies which will have to grow substantially by 2020 to match the projected 30%/year growth rate and 1TWp cumulative installed capacity implied by Trina's graph.
All this means that Solar PV is not going to be a significant contributor to global energy for a long time. If this were understood it might encourage investigation of alternatives rather than continued wishful thinking.
By Edmund Kelly