OutdoorGearLab

The Goertek 25,000mAh battery pack is a high-capacity battery; it has three USB ports that deliver rapid charge to small electronics. We love that it has a large capacity and can fully charge a phone multiple times when the battery is topped off. Additionally, the small solar panel works well enough for the battery to replenish using solar, even if it takes a few hours. In addition to all these great features, the Goertek rings in as one of the most reasonably priced options for solar charger set-ups. 
Our issues with this battery pack are similar to the problems we've had with other battery pack/solar options &mdash; patience is required. This product does not work that well as a solar charger alone; if you're planning to fully charge the 25,000mAh battery off the sun, give yourself a few full days. That said, the panel will continue to trickle charge the battery pack, even when small electronics are plugged in, which is a feature that we appreciate. 

Solar Power Bank Comparison