When buying a solar charger, it is important to check some key features. The first feature is power capacity. Different devices need different amounts of power. For example, a smartphone needs less power compared to a laptop. Make sure the solar charger has enough power output to charge your devices properly. The second feature is charging speed. Some solar chargers are slow, especially in cloudy weather. Look for models with fast-charging technology. These chargers can charge your devices quickly, even when the sunlight is not very strong.