The United States has significantly hiked tariffs on solar products from four Southeast Asian countries, Cambodia, Malaysia, Thailand, and Vietnam, in a move aimed at Chinese companies that have been funneling products through these countries to avoid tariffs and lower prices. The tariffs, which range from 34.4% to 3,521%, effectively make the products "unmarketable" in the US, according to the Wall Street Journal.

The decision comes after long-running Commerce Department investigations into whether Chinese companies were circumventing tariffs by routing their products through Southeast Asia. The move is seen as a escalation of Donald Trump's trade war with China, which has roiled global markets with drastic tariff proposals this month. The president recently called a 90-day pause on tariffs, excluding China.

The tariffs have sparked a mixed reaction from US solar companies. Domestic manufacturers, who petitioned the Commerce Department to investigate, welcome the move as a way to level the playing field. However, renewable energy project developers are concerned that the tariffs will raise costs for construction and the manufacturing of panels in the US using imported cells.

Cambodia, which refused to comply with the investigation, faces the highest tariffs at 3,521%. Duties for companies in Vietnam reach as high as 395.9%, 375.2% in Thailand, and 34.4% for Malaysia. The US International Trade Commission still needs to weigh in on the proposed tariffs in June to finalize them.

The impact of the tariffs is significant, as the four affected countries accounted for more than three-quarters of total module imports to the US last year, according to Bloomberg. The move is likely to have far-reaching implications for the global solar industry, which has been grappling with the trade tensions between the US and China.

The escalation of the trade war also raises concerns about the future of renewable energy development in the US. The solar industry has been a key driver of clean energy growth in the country, and any disruption to the supply chain could have significant consequences for the sector.

As the trade tensions continue to unfold, the solar industry will be closely watching the developments and assessing the impact on their businesses. The final decision on the tariffs is expected in June, and it remains to be seen how the industry will adapt to the new reality.