Advances in technology mean today’s solar panels are smaller, lighter and more efficient than ever. case or hang from the back of your pack while hiking. So long as you’ve got enough sunlight, the best solar chargers can indefinitely extend the life of your power pack.

Solar panels are also used to keep the batteries of cars, motorhomes and boats from going flat when they’re not being used, as most panels will start working automatically as soon as sunlight hits them, meaning you can set them and forget them.