I got the one last year from Aldi, 1500mAh battery though.
It sits on top of the rail for the vertical blinds in the conservatory very close to sunlight and it's here it's at it's most effective, right next to a clear roof. On a kitchen window say, with no direct sun, it's bollocks
Even so, takes several days to charge up, not hours! maybe 3-5 days
BUT you can charge it from USB also - often just needs a little top up as has some charge from Solar.
To take on trips, it's been a life saver, to say's it's a Solar charger, it's pants!
Jeff