I’ve been looking closely at folding, portable solar USB chargers over the past few days. From what I can tell, units with these high-efficiency SunPower cells go for ~$2 or more per nameplate watt delivered to the US. So, $50, or $52.98, for a 28W unit is likely as good as it’ll get any time soon.
I ended up finding a 21w 3/panel on Amazon for ~$36 with same day delivery, so I snapped it up and wrote the first review. I only gave it three stars because the product description was self-contradictory and didn’t quite match what I received, but near as I can tell, it performs like most of the other products in its class that people reviewed. With good sun, good orientation, and no shadowing I could pull ~10W in the early afternoon using an adjustable load. Later in the afternoon, I could charge two USB powerbanks — a Jackery ThunderX 20,000 mAh and a thin Xiaomi 5,000 mAh (pouch sell) at about 2.4A combined, though I think it may have been capable of more.
Anyway, $52.99 for these BW-PW3 look like a good deal.
According to BlitzWolf site:
...If the device is not disconnected and reconnected, it can take up to 10 minutes for the BW-L3 to resume charging the device...
They tried to rush to launch during BG Anniversary period, but the design was not ready for mass production unfortunately. After 2 months of further testing and new material acquisition, they have finally announced that BW-L3 is ready to be released. By the way, $49.98 was pre-order price (closed) for public.