Do-It-Yourself "Dude": Collecting Passive Solar Energy


Every day of an Israeli summer is a beach day. With rarely a cloud in sight, it doesn't rain for about half of the year. Faced with strong sunlight and desert climate, Israelis have found creative ways to make use of the Sun's potential over the years. Most homes today are equipped with a "dude shemesh" (sun water heater)- a simple contraption where water from a tank is pumped into pipes coated with a black collecting surface. It is cheap, simple and reliable. Is the "dude shemesh" an Israeli invention? Israelis seem to think so. The dude in Israeli cities and towns is as ubiquitous as pigeons and hot dog stands in New York. "American hot water heating is always on and is always wasting electricity or gas," says David from Israel on Survival Blog. "Passive solar is cheap and simple plus it can be supplemented with electrical on cold days. Being in the West Bank I also see that the Arab homes and mansions will always have at least one dud shemesh."

The simple black panels of the dude attract sunlight and become hot. The pipes transfer this heat over to the water, which runs back into the water tank. Unless your house has a "dude" you must be remember to turn the electric boiler on for hot water- or use a timer. Unlike in Canada, and the US the average Israeli house isn't equipped to keep hot water brewing all day. Over here we rely on the sun, or a half-hour pulse of electricity needed to heat the tank for a shower or doing the dishes. In the beginning it was really irritating to have to remember to turn the tank off, but now I appreciate using only what I need. My electricity bills stay low.

David suggests the basics for a D-I-Y dude:

"If a commercial model is too expensive, construction is simple and cheap: the collector is about 1.5 m x. 75 m; and a 7 to 8 cm deep panel placed at the lowest south facing part of the roof.

Hoses carry the water up to the "dude" or tank, which is as high as possible. Israeli tanks are insulated when situated on the roof, but some cheaper and simpler models can be found in Arab villages where they make use of a simple black plastic tank placed on stilts.


Convection carries colder water from the bottom of the tank into the collector and hot water rises to the upper intake on the tank. On cold winter days we set the timer to run the immersion heater built into the tank as on days near-freezing the heater barely produces luke-warm water. 
A wood framed glass-paned collector with black painted PVC pipe would likely make a great collector and a plastic barrel would probably make a good tank with a little Bondo work. 
Insulating the tank would make for warm water in the early morning.


If a tank were suspended above the chimney it might be able to grab a few more precious BTUs from the hot gasses during the winter.

Israeli water heaters will run near boiling. It is possibly easier to heat and insulate a small amount of very hot water than large tanks of less hot water." :: Commercial company Makor Hateva :: Energy Crises Now ::Survival Blog