Solar powered lanterns are a rensponsible way to make your garden look great, without affecting the earth. Most outdoor lanterns are connected directly to a mains sourse of power, burning coal, and using up the earths resources, for a little bit of light. Some can even be powered by alkaline batteries, which are harmful to the envoronment. Most solar powered hanging lanterns are water and weather proof so they can be left outside all the time, and will always be on at night when you need them most.
Each solar powered lantern has a solar collector panel to convert sunlight into electrical energy. Just remember that a solar lantern will only work based on how much sunlight it gets during the day, so try to find somewhere sunny during the day, but that will offset a great feature of your garden at night. A popular location is along garden paths , or even the entrance to your house, to make it easier for your visitors. Just remember, solar powered hanging lanterns aren't the best choice for all your lighting needs, and they need to be less bright that traditional lanterns. However i think most people agree this is a reasonable trade of for the environental offset.
You may intitally be offput by the idea of solar powered lanterns, however these days they use very efficient, longlife batteries, which are only recharged by the sun, and the latest in LED technology to cut energy use, which are also very reliable compared to traditional bulbs. They tend to last longer, and be much brighter than the older solar powered lanterns you may have seen in the past