Solar capacity in the UK could reach 18GW by 2020, and could soar to even higher levels if policy support for other technologies is diverted to solar in the wake of policy changes according to the latest Future Energy Scenarios report issued by the National Grid.

This year's edition of the study, published on Wednesday, predicts the deployment of energy generation technologies depending on various economic and policy factors and determines what the risks to the National Grid might be.

Both the ‘no progression’ and ‘slow progression’ scenarios paint a tale of minimal uptake all the way into the 2030s with little support from government and a tough economic climate, while ‘gone green’ and ‘consumer power’ scenarios include continued support for renewable technologies, accelerating their adoption.

Under the consumer power scenario solar PV capacity could reach as high as 18GW by 2020, slightly missing former energy and climate change secretary Greg Barker’s ambition of 20GW by 2020, however the difference between that and the bleakest scenario of no progression is stark, with National Grid projecting just 8.6GW – a minute increase over current expected capacity as of Q1 2015.

By 2030 the consumer power scenario predicts solar capacity could have topped 29GW, a substantial increase over other scenarios which the National Grid said would be typified by favourable economical conditions promoting research and development of new technologies, coupled with a strong decarbonisation effort in the UK.

If the consumer power scenario is to ring true National Grid forecast 46% of energy generation demand in the UK could be met by solar PV and wind by 2035, but again the no progress model forecasts that just 11.3GW of solar capacity could be installed in the UK by 2030 if conditions are unfavourable.

However the National Grid has also added a caveat to its own projections in the form of a ‘solar sensitivity’, which it said was included as the organisation acknowledged that its models are based on information available as of January 2015 and therefore “may not capture the true potential” of solar in the UK.

Since January the UK has witnessed an explosion in added capacity prior to the expiration of the RO deadline on 1 April, and Solar Intelligence recently disclosed its own market data that showed in excess of 2.5GW of capacity was added in the first quarter of this year – far exceeding Department for Energy and Climate Change forecasts.

The sensitivity includes projections to take into account potential change to support mechanisms for other technologies that could divert more funds to solar PV – a reference to future allocation of CfDs – to project as much as 21.2GW of solar by 2020 and 32.7GW by 2025.

Finaly Colville, head of Solar Intelligence, said that predicting solar deployment up until 2020 and 2030 was a “very hard task” given how quickly the reference solar data can become out of date.

“Another problem is that by the time any long-term report comes out, the current data at time of release may look on the low side, especially in the case of solar. Given that the UK is likely to have installed over 10GW before the end of FY’16, regardless almost of anything that may change in policy, an interesting forecast would have been to take this figure as fixed as of 31 March 2016, and then run the scenarios from 1 April 2016 using 10GW as the existing solar capacity then,” he added.

The report also states a number of trends it expects to record in solar over the coming years, most notably a geographic shift to the north of the country as developers look to move into areas with fewer grid constraints. A System Operability Framework document is to assess the implications that installing substantial volumes of solar PV will have on overall grid stability and is to be released in Q4 this year.

Energy storage is also covered extensively in the report given its propensity to solve some of the grid balancing issues referenced throughout, especially given the expected rise in distributed generation and microgrid networks in the country. The report states that the amount of energy demand for an average household met by a solar PV installation would increase from 30% to as much as 80% if a battery was added to the system, and suggested only one or two developments such as additional policy support or the introduction of time of use tariffs would unlock storage’s potential in the UK.