This is for a science project, so make sure it is not too big or expensive.
Use a small satellite dish(18) cover surface with reflective mirror material, in place of LNB mount canister with inlet check valve, place thermostat valve rated 130 to 160 deg f on outlet. sun will heat water valve will open on temp. drain hot water to insulated tank, pump water back into focus can, repeat process.
Use a shiny, smooth, round shaped, steel dish, if you hold it against the sun it would consentrate the light into one point, and the heat would be consentrated in that point, arrange a way to put some water in there and it would be heated. You can contact me for more details but it really is a easy one.
Plastic tubing. Black. In Australia we use black plastic tubing on house roofs to heat pool water. A very shallow tray painted black to absorb heat. Stick to the top a clear piece of perspex with silicon sealant. Have a hose leave the end of the tray and loop around to the other end of the tray to the top of an ice cream bucket. From the bottom of the bucket (side) run a hose to the end of the tray. Place the tray in the sun on an angle with the ice bucket higher. Pour water in the ice cream bucket. Hope you tested for leaks. The cold water will fill the system The sun heats the tray, and the water. The hot water rises up the hose from the top of the tray to the top of the bucket. A cycle begins. Colder water at the bottom of the bucket flows down the hose to the bottom of the tray. Enters , gets hot and cycle continues. For use add tap to near bottom of bucket and top up via float if you want to get fancy. good luck on building your solar hot water system.
