The contest underdog – who has spoken of how his young daughters urge him to act on the climate emergency – nevertheless pledged to put preserving farmland first.
“On my watch, we will not lose swathes of our best farmland to solar farms. Instead, we should be making sure that solar panels are installed on commercial buildings, on sheds and on properties,” Mr Sunak said.
But the stance was attacked by an author of the Conservative election manifesto, who said even the government’s target of a five-fold increase in solar farms would cover only 0.5 per cent of available land.
“I see Rishi has joined Liz in highlighting the scourge of solar panels on our precious farmland,” Robert Colvile posted on Twitter.
“You can tell this is about Nimbyism not preserving arable land for food supply because we currently devote way more land than solar would need to growing biofuels to thin out our petrol.”
Mr Colville said the UK had 23 million acres of farmland, adding of putting solar panels on it: “Also you can usually still farm on the land!”
The foreign secretary has been accused of selling out farmers in the post-Brexit trade deals she struck with Australia and New Zealand, as trade secretary.
Until now, all Conservative ministers have pointed to the trade deals as a Brexit success, despite the tiny economic benefits from them.
But Mr Sunak told The Daily Telegraph: “In any trade negotiations I would fight for the interests of our farmers rather than trading away their interests for the sake of meeting self-imposed deadlines.”
He promised to reduce burdens on farmers by slashing remaining Brussels rules, replacing fines with warning letters and merging a number of government quangos into one new “Agriculture Agency”.
A new target would ensure more crops are grown in Britain, with a particular focus on tomatoes and cucumbers, so that salads no longer have to be imported.
“We have flexibility now – something we certainly didn’t have as members of the European Union,” Mr Sunak said.