Charging times between your solar panel and power pack will vary based on weather and the type of product used
You'll collect the most power from the sun on bright, clear days. That being said, solar panels utilize IR, UV, and visible rays from the sun that can penetrate through clouds. Although the efficiency of the solar panel will decrease in cloudy conditions, you'll still be collecting valuable power from the sun. Also, keeping your solar panel angled toward the sun can dramatically increase efficiency. Set it up and let Mother Nature do the rest.
Most USB and 12V devices can charge directly from solar panels, if the weather conditions are good enough.
Small USB devices like cameras of MP3 players require 1-2.5W of constant power to charge. Our panels can easily provide this amount of power even in sub-ideal conditions. Smartphones and tablets have a higher power requirement, usually around 5W of constant power. A 7W rated solar panel will only produce 5W in perfect sun conditions, and because smartphones are quite picky about their power requirements, they can "give up" charging if there is ever an interruption in constant power - like when a cloud passes by overhead.
For the best experience, we recommend using a Goal Zero battery pack as a buffer, instead of charging directly from the sun, for the following reasons:
Heat and batteries are enemies. Precision electronics don't like heat either. When charging directly from solar, care should be taken to keep the device with the battery in the shade. The shade of the angled panel is a good option. Do not store devices next to the panels when charging. The heat will lower the life of the battery.
Weather uncertainty. Your phone may not be weather durable. Keep it protected.
If clouds pass by or weather changes, the charging can become interrupted. Phones will often reject the charge in cases like these. This means your phone could be sitting out there and not charging. Batteries give you a constant charge no matter the weather conditions. Goal Zero Rechargers/Power Pack charge well with solar regardless of the conditions – they never reject a charge opportunity.
You might not want to sit out in the heat of the sun, if you need to use your phone while it charges. Battery lets you move anywhere.
You use your phone during the day and charge at night. Solar doesn't work at night, but batteries work anytime.