The Ray has a built-in solar cell that harvests energy from both indoor and outdoor light.
How much light does it need?
Just 1 minute of direct sunlight per day is enough to keep the Ray running indefinitely. Indoor light works too — it just takes a bit longer to top up.
What if I don't get any light at all?
The Ray has a 60-day "cave mode" — even in total darkness, it will keep tracking for two months on a full charge.
Do I ever need to plug it in?
No. There's no charging port on the Ray. It's completely self-sustaining.