I tested the BigBlue SolarPowa P25 25W solar charger for three days at around 30° latitude and 400m altitude in October under clear skies, and I’m quite disappointed with its performance. When charging my phone directly, it consistently overheated and stopped charging after only 12–15%, even when the phone was kept in the shade. Charging a 10,000mAh power bank gave similar results, barely reaching 20% after a full day in the sun. Despite its 25W rating, the panel never produced more than 5W output, with an average charging current below 1000mA before overheating cut off the charge. Overall, I regret buying it and find it underpowered for practical use at moderate altitudes, though I still plan to test it at higher elevations where cooler temperatures and stronger sunlight might yield better results.
