In the Carbon Plan, DECC published a range of possible scenarios (based on modelling by Redpoint Energy) for electricity generation from renewables in 2030 (see here: http://www.decc.gov.uk/assets/decc/11/tackling-climate-change/carbon-plan/3702-the-carbon-plan-delivering-our-low-carbon-future.pdf, page 73). The analysis considered a range of decarbonisation scenarios consistent with meeting carbon budgets and the 2050 goal. The analysis showed that renewable electricity could provide 35 to 50 GW by 2030, with the upper end assuming either high electricity demand or significant cost reductions. It is important to stress that these are not projections, but some of the possible scenarios to meet our carbon budgets and 2050 target.
In addition, the Carbon Plan sets out four plausible pathways towards 2050. Details of these pathways are set out in annexe A of the Carbon Plan: http://www.decc.gov.uk/en/content/cms/emissions/carbon_budgets/carbon_budgets.aspx.
These were produced using the 2050 pathways calculator tool, which supports users in exploring these and other pathways in great detail. It is available at: http://2050-calculator-tool.decc.gov.uk/.
Based on the four plausible pathways set out in the Carbon Plan, solar photovoltaic panels and solar thermal could together produce between 0 and 27.4 TWh of electricity and heat in 2050.
However, the calculator explores the boundaries of what would be physically possible for each technology, representing level 1 as little or no effort to reduce emissions, to level 4 as extremely ambitious changes that push towards the physical or technical limits of what can be achieved. Level 4 for solar PV is an extremely ambitious level of deployment without precedent anywhere else in the world, equivalent to 10m2 per person, or covering all south-facing roofs of domestic properties. Level 4 for solar PV would yield 140 TWh of electricity by 2050, as set out in the answer given by my honourable friend the Minister of State for Climate Change to the honourable Member for Stockton North on