The unit looks good - but as mentioned on a previous review, the minute I held it I knew something wasn't right. I have a similar Power Bank @ 8000mAh and it weighs nearly 3 times has heavy yet holds storage nearly a third less than this one advertised as 30,000mAh.
Once tried, it was clear - I was lucky to get one full phone charge (approx 2,000mAh) out of it when it was fully charged.
This is basically a tin box with a small rechargeable battery in - its not 30,000mAh - no way - unless the Chinese have invented a mass production light weight rechargeable battery capable of mass storage for a few quid.
Advice - steer clear and focus on similar ones which claim to be 5,000 - 10,000mAh... You stand a good chance of actually getting a product as described/labelled. Also - Remember - the size of the solar panel - the solar is for trickle charging the power bank only - don't expect to charge your phone or power bank by leaving it in the sun for a few hours. A few weeks, maybe :-) This applies to all products of this type.
Since it's suspiciously lightweight, I opened it up and there were only two thin LiPo cells inside. No markings, covered in sticky tape, and as bare LiPo batteries are soft and fragile, I didn't explore further. However, I estimate there's probably 5000 mAh in there, max.
The pack does work, though. Just not as advertised.
30000mAh is rubbish its only 6,000mAh iv opened it up my self. The solar cell is point less as the charging LED use more power that the solar cell can produce. You will be waiting about 60 day for the solar cell to charge the battery. Over all a bit crap