About 39GW of foreign-made solar panels flooded into the US through three quarters, a national record for the period, as the industry ramped inventory levels with looming expiration of a waiver on import duties on certain Chinese-branded products from Southeast Asia, according to S&P Global Market Intelligence.

While the surge in imports is helping drive this year’s solar development boom in the US, it is also stoking concern among some manufacturers who have announced new factories or expansion of existing ones in the US or aspire to do so.