JBL is currently crowdfunding for their project of creating a solar/light powered headphone. The JBL REFLECT Eternal: Self-Charging Headphones is marketed as wireless headphones with virtually unlimited playtime. So according to the company, under the certain conditions it’s possible that the headphone will never need to be plugged into an electrical outlet. The product is sustainable, eco-friendly, and convenient.
Based on a figure of 3.5 hours of listening daily, 1.5 hrs outside per day adds up to 68 hours of playtime, and 2 hrs outside daily adds up to 168 hours of playtime. Therefore, supposedly 2.5 hrs outside per day would add up to become unlimited playtime. JBL offers many power source alternatives to the product. So with their technology, the headphones can be charged using indoor artificial light or USB charging as well.
However, you can potentially receive the headphones for $99 for a 40% off discount by supporting now. The estimated time frame for backers to receive products is October 2020. You can find more information about the JBL Reflect Eternal headphone through their online campaign.