I'm puzzled by this. According to the Guardian article, the ban will affect 3b land, which (according to the government website) is:
"Subgrade 3b – moderate quality agricultural land
Land capable of producing moderate yields of a narrow range of crops, principally:
cereals and grass
lower yields of a wider range of crops
high yields of grass which can be grazed or harvested over most of the year"
So it affects mainly grazing land, not land used for crops for human consumption. My understanding is that fields with solar panels can still for animal grazing.
I must admit I find it contradictory. I thought Truss' idea was to leave everything to the market and encourage growth, so why is she apparently introducing more- red tape and restrictions and restricting growth of renewable energy? If farmers want to make more money from their land by installing solar panels, shouldn't the free market economy allow them to do so? After all, farmers haven't exactly been treated well post-Brexit.