I recently bought a "Chinese one from ebay. It was cheap, works perfectly, and likely has exactly the same innards as any non-Chinese PWM one that has some other branding.
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Β£15.59 for a 20amp one.
The biggest concerns I have about buying Chinese branded products is whilst they may look very similar to well respected brands, and in some cases they may even be the actual manufacturer for the respected brand, and adhere to good practice and consistent quality for that brand, but that does not guarantee what's inside their own branded product is the same.
What is also a problem with some Chinese branded products, is their not always consistent inside from batch to batch. There is one YouTube creator who often (and deliberately) reviews cheap Chinese electronic products and finds despite outwardly looking the same, it's pot luck with what's inside, and it's very worrying how many items have significant design or manufacturing flaws that render some of them very dangerous to the point of being lethal in normal use. What's also disturbing, is how many of these products show fake safety approval marks leading buyers into a false sense of security. (Edit) in addition it's also quite amazing how some products fail entirely to do what they claim to do, clearly by design, rather than error.
It's a real shame, because there are some real gems out there, that genuinely do work well, and do meet our safety standards, but they are often difficult to identify amongst the offender's which look near if not identical.
For equipment that will often not be supervised for long periods such as solar chargers, I'd recommend avoiding products with suspiciously low prices, or other "to good to be true" deals from the plethora of sources selling unrecognised brands.