Cold water flows up to my roof through pipes and gets heated in the collector. The hot water flows down through other pipes into my house so I can take a hot shower or a bath. Most people use electricity or natural gas to make hot water. But if you live in a place where it's often sunny, you have probably seen solar collectors on people's roofs. The next time you go for a ride somewhere, look at the roofs as you pass houses and buildings to see if they have solar collectors on them.
Solar collectors collect the sun's heat.
You'll be seeing a lot more solar roofs as you get older. The President of the United States has promised to help put a million solar collectors and solar panels on roofs by the year 2010.