NoPinky

in all kindness of this site, but the title is missleading and the resulting object is useless and not even nice to look at. Why did you even do this? °_°

Why would you need such a big box? It is all empty inside, isn't it? °_°

as mentioned above, use diode to prevent discharging over the panel. another thing is: your assumption of the charging current to be 60mA is way off. That tiny calculator solar cell won't even give you 1mA, it is actually only about 10uA. So you would need far more than 9 hours (54000 hours)