A new solar thermoelectric device is in the offing- and what’s cool is that it can be retrofit into existing solar water heaters to gain the benefits. This means the payback for adding the device is amplified. Dr. Gang Chen and ZhiFeng Ren and twelve colleagues and doctoral students (MIT, Boston College, GMZ Energy (founded by the primary authors), and Masdar Institute of Abu Dhabi), published these results in Nature Materials.
There are currently two big processes used in converting sunlight to electricity. The primary device that comes to mind are the vast arrays of movable mirrors; computer systems are used to move the track the sun, move the arrays, and have that energy focused on a small area. Another approach (solar thermal power plants) involve heating a fluid inside of tubes that is used to boil water and drive a conventional steam turbine generator. But, by far, the most prevalent use of solar power are the roof-top gadgets that convert solar energy into hot water for direct home and commercial use (albeit producing smaller amounts of converted energy).
The new concept described in the publication is based upon the principle that temperature differences across a solid material generate a voltage. (In other words, if one side of the solid is hotter than the other, electrical current is generated.) This is called the Seebeck effect. (When two metals joined in two places have a temperature differential between the junctions, there is a different response for each of the metals (due to differing thermal conductivity). This creates a current loop (and a magnetic field). This was termed “thermoelecticity” by Hans Christian Oersted. One such combination, copper-constantan, can produce 41 microvolts per degree (C or K) of temperature differential.)
Current solar water systems typically use a black absorber that collects the heat and transfers that heat to water flowing through a copper pipe. The current research involved coating copper with a nanostructured material and placing that flat object (the heat absorber) into a vacuum. Instead of directly attaching the absorber to the copper pipe, two “legs” are attached, which lets the electricity flow, as well as heating the water in the copper pipe. But, this concept also differs by placing the solar thermal electrical generator (STEG) in a vacuum. As such, the heat that is absorbed is “captured” (not released or reflected via convection, as would be true with conventional solar absorbers.). The hot water that is produced reaches some 60 C (140 F), hot enough for use in showers and dishwashing. The concept still lets the rest of the energy to afford the absorber to develop a temperature differential of some 200 C (almost 400F) from the ambient conditions. This temperature differential is what drives the electrical current.
One should note that the photovoltaic efficiency of solar panels are much higher than this device. This improvement is strictly aimed at improving the efficiency of solar water heaters.
That is a very informative article but hot water heating still seems more reliable to me.
Solar hot water would STILL occur with this system. It’s an add-on, to let you generate electricity at the same time. In other words, it’s a means to augment the collection of the solar irradiation to obtain more benefit. That’s the key point. Sorry I failed to make that clear.
Roy
I am a big admirer of environmentally friendly gadgets and equipments. However, since this technology is quite expensive, I am still not ready to invest in one. I know it will pay for itself in the long run, but it’s still not yet time to change my storage tank water heater. Maybe in 3-5 years time.
Jonathan Sparco@TopWaterHeaters.com recently posted..Tips in Choosing On Demand Tankless Gas Water Heaters
Jonathan:
Thanks for dropping in! And, you are right- there is no need to change one’s current technology unless and until the new technology can pay for itself in less than 3 years or so. Since yours is functional and paid for (presumably), there is no need to replace it- unless it ceases working or fails to supply a new requirement.
I am NOT for conspicuous consumption, either.
Please visit soon!
Roy
It is good thing I think if you want to go forward there is need to be search new thing !! Solar hot water will save our electricity !! Hope your thought will get positively by public !!