The Solar Trade Association (STA) said that estimates published by National Grid in its future energy scenarios on Thursday fall “far below” other estimates and “need to be revised”.
Paul Barwell, chief executive of the STA, said: “It is frustrating that both the Government and the National Grid are basing important decisions on out of date data.
“This undermines what the solar industry has achieved so far and risks holding back solar’s potential.”
He added: “We forecast that solar will become cheap enough to compete without public subsidy by the end of the decade, but only if it has a stable policy framework. Using accurate data is an essential part of that.”
National Grid’s two green scenarios predicted only 7.5GW and 8.5GW of installed solar capacity by 2020, whereas even the Department for Energy and Climate Change (Decc) estimated 12GW, and climate change minister Greg Barker has an ambition for 20GW.