Long version: First; the diode all the other reviewers are arguing about. No, it doesn't, and that's a good thing. While you certainly can, you really shouldn't just hook this up to a battery. You will need to use a specially selected minimum quality charge controller, which will almost certainly have its own. If you're wondering why not have both; The reason is that each diode drops the voltage by 0.6 volts. Doesn't sound like much, but if you're using this in an area with little sun it could make a difference. In my usage I had a rarely used machine that had a badly drained battery. I paired this with a homemade MPPT controller bought here at Revain for about $13. Since my car's cigarette lighter port is only plugged in when the car is on, I connected the battery through an "Add Circuit" fuse, also purchased here at Revain for about $7. This didn't work at first because I placed it on the dashboard so that it was slightly tilted towards the sun. Once I put it as close to the sun as possible, everything worked perfectly.