How efficent are solar water heaters, how do they work?

Answer 1

It depends on a variety of factors. Are we talking photo-voltaic cells or are we talking black-painted pipe-grids?

Are they lagged? Are they sited in a high-sunshine area? What are they used for?

How solar power works to heat water:

Photo-voltaics (those shiny black "chip") is converting solar energy into proper electricity which can be used to power all manner of systems- from lights to heaters. Commonly they are smaller units mounted on roofs (either fixed panels or movable units to follow the path of sun) to convert rays to power and send them to be stored in a battery. The battery then powers whatever.

The simpler system (and commonly used in high sunlight regions of the world such as India, where I came across them as a child) is where you pipe your tank water via a long pipe which snakes up and down over a black panel and are, themselves, black coated. Black colour absorbs light and heats up (if you ever had a black car and sat on its black seat in the summer you KNOW what I mean!) so that the water which is lying in the pipe is heated. Notably the water is only heated in the pipes so flow has to be slow or it has to be over a large area. It is possible to paint the roof mounted water tank black too and so that the water rises (as it heats) into that tank and is further "warmed" to provide you with ever pleasant shower water.

Other systems exist but the subject is a minefield.

It really depends on what you are talking about- ie what application and why, where, how much etc!

Answer 2

Solar water heaters—also called solar domestic hot water systems—can be a cost-effective way to generate hot water for your home. They can be used in any climate, and the fuel they use—sunshine—is free.

Solar water heating systems include storage tanks and solar collectors. There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don't.

Most solar water heaters require a well-insulated storage tank. Solar storage tanks have an additional outlet and inlet connected to and from the collector. In two-tank systems, the solar water heater preheats water before it enters the conventional water heater. In one-tank systems, the back-up heater is combined with the solar storage in one tank.

Answer 3

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Answer 4

thy are pretty effective because they store they heat from the sun and they make hot water they are really cheap to use I recommend it for ever body. When you get one you will have to put the solar panel on your roof faceing south to get the most energy out of it.
I hope this help ya

Answer 5

If the sunlight is good, the temperature of water in tank can increase about 30-40 ℃.
When the sunshine irradiate on the collector and converted into heat energy, then the water in collector is heated, the heated water transfer the heat to water in tank through the convection.

Answer 6

Sunlight is absorbed by the selective absorbing coating on the outer side of the inner tube when sun is on the vacuum tube and converted to heat energy, Finally heat energy is conveyed to heat water in the inner tube. The density of water decrease with the rising of water temperature, and then form convection of the water in the tank, making water temperature rise inside the water tank.

Answer 7

In Ariz it worked great. In Mich not so good.Usually anti freeze is pumped through a system.It gets hot and transfers it to the water.

Answer 8

they are great if you live in a sunny area. a solar panel is connected to them that powers the battery to it

Answer 9

in the south and west they are very good. if you want to know how they work just pick up your garden hose after it has been in the sun for few hours. that should answer your question

Answer 10

http://en.wikipedia.org/wiki/Solar_water_heater
hope this will help