Depending on the season, the weather condition (fog, clouds), the altitude, the dust in the atmosphere, the distance from the equator and other variables, it can be more or less difficult to fully charge the WakaWaka with solar power. For example, an hour of sun in the winter gives less UV-light than an hour of sun in the summer.
The further you are from the equator, the longer it will take to fully charge the WakaWaka via the sun.
It takes approximately 18 hours of direct sunlight to fully charge your WakaWaka Power+, 5 to 10 hours to fully charge your WakaWaka Light, 4 to 8 hours for your Power5 and 6 to 12 hours for your Power10.
When your WakaWaka is almost completely out of charge, it can take a lot of time to charge the first 25% (from 0 to 1 light). This is also the case for the last 25% of charge (from 3 to 4 lights). This is to protect the battery of your WakaWaka. In short, charging between 25% and 75% is relatively quicker than charging to 25% or beyond 75%. Therefore, we advise you to not let your WakaWaka drain completely before recharging.