The Department of Energy and Climate Change is standing by its forecast for solar capacity out to 2020/21, showing minimal growth for the sector over the next five years.

The news comes from a written answer issued by energy minister Andrea Leadsom last week to a question from Coventry South MP Jim Cunningham, who asked the minister what estimate the department had attached to solar PV energy production in each of the next five years.

Leadsom referred to projections published in August which placed UK solar capacity at 9.55GW by 2021, equivalent to roughly 9.1TWh of generation or 2.8% of the UK’s total.

The dataset also clarifies how the figure is expected to grow from next year out to 2020/21, stating that solar generation as a percentage of the UK’s total will stay at 2.6% over the next two years before rising to 2.7% over 2018/19 and 2019/20. Solar is then forecasted to climb to 2.8% in 2020/21.

While Leadsom did qualify the estimates by stating them to be subject to change owing to legislation, DECC’s forecasted generation of 9.55GW should be of concern for the industry given that the department placed total solar capacity at around 8.2GW just last week.

This would equate to DECC forecasting there to be just over 1.3GW of new solar PV capacity added to the grid over the next five years – little more than half what was added in Q1 2015 alone.

The figures would also seemingly contradict previous comments made by energy secretary Amber Rudd which sought to allay fears that cuts to government subsidies would cause the industry to shrink substantially.

During a DECC oral and topical questions session in parliament on 17 September, Rudd shrugged off questions relating to job losses in the industry. “Solar is a great opportunity for consumers and for business, and I believe it will continue to flourish,” Rudd said at the time.

But there are also concerns over the accuracy and relevance of DECC’s data. The department has frequently struggled to keep up to date with strong levels of deployment under the Renewables Obligation scheme and forecasts made by Solar Intelligence indicate the same is happening with installations made under ROO-FiT.

Last week Solar Intelligence reported that UK solar was to breach the 9GW capacity carrier just days after DECC released its own 8.2GW estimations. Finlay Colville, head of intelligence at Solar Intelligence, said that if DECC’s 2020/21 forecasts are to be believed then the government is estimating just 550MW of new solar installed in the UK over the next five years.

“It is highly unlikely this forecast from DECC will come true, and is likely to be met by the end of the current fiscal year, ending 31 March 2016, some five years earlier than DECC's current estimate. Once again, it flags the problem policy makers are having in both keeping up to date with a rapidly moving sector, and also in forecasting future deployment levels,” Colville added.

The Department of Energy and Climate Change had yet to respond to requests for comment at the time of publication.