Solar Hot Water Kettle From Plastic Bottles (and Glass)

Step 5 Add reflector foil tape

Attach foil tape to the outside of the 2-liter, just go half way around the bottle. This becomes somewhat of a parabolic reflector and lets the sun shine a little brighter on the backside of the center bottle.

Comments

[scubagal]

What about using old CD's or DVD's to reflect the sunlight?

[robbtoberfest]

That would do it, just not as easy as foil tape :)
Check this one out http://www.instructables.com/id/Parabolic-solar-ray-gun-a.k.a-solar-death-ray/