Guides
Since 2026, US storage projects lose their tax credit if too much of their equipment comes from companies tied to China, Russia, Iran or North Korea. These guides explain the rules, the lists behind them, and how the directory traces a supplier's owners.
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What is a prohibited foreign entity?
The 2025 tax law's test for Chinese, Russian, Iranian and North Korean ties: specified foreign entities, the 25% and 40% ownership tests, debt, and control.
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The material assistance cost ratio for battery storage
How the material assistance cost ratio works for energy storage under section 48E, the thresholds from 55% in 2026 to 75% from 2030, and a worked example.
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The US restricted lists that matter for batteries
Which US government lists make a supplier a specified foreign entity, which are only warning signs, who publishes each, and how often they change.
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How we trace a supplier's owners
The method behind the directory: which filings we read, how shares multiply up a chain, how covered owners are added up, and what we cannot see yet.