Polysilicon, the base material for silicon solar cells, just returned to its very low price level of a few years ago. A big driver behind the solar panel/module price, resuming its long downward development with record low prices these days.
Via @barnettenergy on the birdsite.
@Sustainable2050 panel production has been greatly expanded, but not inverters. They’re still pretty much sold out. So no wonder that panels are in oversupply and prices are falling. Really hoping inverter production will catch up to demand soon, so all these panels can be put to work.

@Sustainable2050

What is the cause behind the fall?

@MaryPot @Sustainable2050
Probably a combination of supply & demand along with China's attempt to blunt the impact of Biden's domestic energy security policies trying to spur manufacturing to come back home to the USA.