[Colin] has put together an instructable for a solar power generator that uses the thermoelectric effect instead of the photovoltaic (PV) effect. We have seen Peltier devices used in cooling cans, solder paste, backs, and hacked hard drives. This is the first hack we have seen where a Peltier device is used to generate electricity from heat, essentially running the device backwards. The thermoelectric effect is the same principle that is used to generate electricity in radioisotope thermoelectric generators used in deep space probes such as Cassini. What applications can you come up with to use the thermoelectric effect as a power source?

We saw this pretty smooth solar tracker run by an Arduino. There aren’t many details, but we can see that it works well, and is in fact, run by an Arduino. We knew if we posted this that people would be commenting that the Arduino is overkill. We agree.  So this post is to ask, how would you do it? Give us links to the more efficient designs you have come up with. It doesn’t have to be a fully documented project, a schematic will do. We would probably go with something like a phototropic suspended bicore for simplicity and low power consumption.

[via littlebirceo]

Though not much info is readly available about it on the web, [Joe Carruth] is trying to build publicity (and venture capital) for his home-built solar electric generator. At its essence, it is a Stirling dish system with an adjustable composite mirror surface. This means that instead of having to rotate the entire contraption in order to follow the Sun, [Joe] only has to make  the mirror segments pivot. A Stirling steam engine at the tip converts the energy into the movement used to generate electricity. Solar power plants (or ‘farms’) that are emerging are beginning to consider the advantages of using more efficient Stirling dishes rather than less efficient solar panels. If anyone has an idea as to how [Joe] can automate sun tracking for the mirrors, please post it in the comments. A couple more videos on the topic (in general) are available below:

Reader [unangst] pointed out to us an article in the U.K.’s Daily Mail, where a teenager from Nepal had managed to create a 9v, 18W solar panel using human hair rather than the usual semiconductors (usually crystalline-silicon). The complex silicon in solar panels are what keep the prices out of reach of developing nations, and while there are a number of new technologies that are helping  bring down the cost, [Karki] managed to make his solar panel for only £23 (roughly $38). He also claims that when mass produced the price could drop substantially down to under $10 a panel, which would shatter the $1/watt sweet spot.

The melanin in hair acts as an organic-semiconductor, and while the hair does not have the longevity that silicon panels have (months rather than years), these panels can be made cheaply and serviced with little to no complex knowledge. Using melanin as an organic semiconductor seems to be a newer idea, because information seems hard to come by, but we managed to find a research paper from 2007 that explored the energy absorption attributes of melanin, as well as some good background info for the science types.

Research Paper (Warning: PDF)

So, Hack a Day readers, which one of you is going to make your home-brew solar panels first? Let us know when you do.

Thanks [unangst].

Strobit looks like it could be a project to keep an eye on. The entire project is open source, including the hardware. The aim is to build a low cost, low power, wireless enable arduino powered widget. This seems like it could really cut down on the development time of many projects we’ve seen here. Development is still ongoing but it looks like they’ve already implemented some mesh networking similar to the zigbee systems.

[via hackaday flickr pool]

Another Cornell final project, Weather Canvas aims to make watching the weather a little more pleasant. Data is captured via a thermometer, humidity sensor, anemometer, and a Hotwheels radar gun turned precipitation sensor. Once it’s captured, it’s transmitted to the LED matrix inside which displays pretty patterns to convey the weather conditions. They have set images, like icons, that mean different things.

[Aaron] a google employee came up with an idea that would be good for the environment, as well as fun. The Radish is a solar powered display, updated from a google calendar, with extremely low power consumption. They are building this to be an indicator of the conference room schedule. When we first read this, we wondered just how much greener it could possibly be than printing a few sheets of paper. Then we read that they were going through six reams per day. wow. The Radish gets its power through a solar panel, and preserves it through some creative power saving modes and the fact that it has an LCD that only requires power to update. Would this be a good place for some E paper? Data is transferred using IEEE 802.15.4, which is slow, but also more efficient in terms of power than normal WiFi. The system is so efficient, it can run for 3-4 days in low light conditions after a charge . Another cool fact is that [Aaron] got to design and build this on company time. Google allows people to spend 20% of their time on innovative new projects of their choice.

correction: the LCD goes into an extremely low power “sleep mode” when not being updated, and retains the last image loaded.

It sounds unbelievable, but it is true. You can harvest most of what you need for a simple solar cell from powdered donuts and tea. Powdered donuts have nanoparticles of titanium dioxide which is a “high band gap semi conductor”.  This means that it can be used to make solar cells. The tea is simply used to dye the material so it can pick up the visible spectrum. The process is a bit too involved to be something you would just toss together in the field, but it’s cute nonetheless.

[Knut Karlsen] put together a prototype set of solar rechargeable batteries. He always seemed to have batteries laying around on his worktable and figured they might as well be charging. The flexible solar cells were given to him by researchers at the IFE and are rated at 1.8V. He used superglue to secure them to the C cells. A silver conductive pen plus flat wires from a Canon lens connect the solar cells to the battery terminals. The batteries just trickle charge for now, but he’s going to try to build cells with built in charge controllers in the future.

The 25th Chaos Communication Congress is underway in Berlin. One of the first talks we dropped in on was [script]’s Solar-powering your Geek Gear. While there are quite a few portable solar products on the market, we haven’t seen much in the way of real world experience until now.

[script] selected a four segment folding solar panel after some research. He pointed out that solar is currently more of a necessity technology than money saving since the panels can be very expensive. For connectors, he recommended ones that were safe, polarized, and difficult to short, like the RIA connect 230 series he used. Most of the device plugs were easily purchasable, but some had to be salvaged from old AC adapters. A key component of his setup was the adjustable voltage regulator. It’s based on the LTC3780 buck-boost controller which is 98% efficient and can be adjusted from 4V to 25V.

[script] covered some of the problems he ran into in use. The first was an Nokia that refused to charge until a resistor was added to reduce the current delivered. Less sensitive devices like portable peltier fridges will work without any issue. For laptop use, he ran into problems with demand spikes killing the power delivery. He added a large cap normally used in car audio systems to make power delivery more consistent. Laptops can consume as little as 15W during normal use, but when they’re charging the battery, the draw can jump to 50W. On his ThinkPad, he was able to turn off charging to prevent this. He monitored the performance of the panel by building a Kill A Watt style device using an ATmega8 to measure current and voltage and log it to EEPROM.

In conclusion, [script] stated that he was happy with his experience, but that it was still impractical to use the portable panel in anything other than direct sunlight.

[Erik Knutzen] and [Kelly Coyne], authors of The Urban Homestead, are really into all things green and sustainable. In their blog, Homegrown Evolution, they discuss building their own solar dehydrator using plans from the February/March 1997 issue of Home Power Magazine. The dehydrator is designed by Appalachian State University’s Appropriate Technology Program. If interested, you can check out or buy other solar dehydrator designs. This seems like a great, cheap alternative to buying an expensive electric dehydrator, and you get some great advantages, like low-cost dehydrating, solar energy, and beef jerky whenever you want it. Plus, the authors point out, for most of these designs, if you remove the top box and you stick it next to a window, you’ve got a solar heater. It’s now a dual-purpose device.

Producing ice without electricity just got a lot easier thanks to these engineering students from San Jose State University. Their system uses solar heat to facilitate evaporation of a coolant. When the sun goes down and the coolant turns back to liquid, its temperature drops drastically due to extreme pressure differences. The unit can produce 14 pounds of ice per day with zero carbon footprint. It has no moving parts and an entirely sealed system, this should mean that the only maintenance necessary would be keeping the unit clean.
[via DVICE]

MIT researchers have devised something they call the Solar Concentrator which is to be placed on top of existing solar cells. Its purpose is to separate the visible and infrared spectra of light by absorbing the visible spectrum and routing the energy to specialized cells. They claim this could lead to doubling the panel’s efficiency and greatly reducing costs.

We have seen many promising advances to solar panel efficiency in the past few years, but what is special about this one is the amazingly simple and cheap technique. Essentially, all the team has done is coat a piece of glass with simple organic dyes. After the organic molecules absorb the visible light, they remit the energy to the sides of the glass where it can be routed to their specific cells. The process is more efficient because the dye absorbs the light rather than something expensive like silicon. That means less silicon, and thus a better price range. Also, the fact that this material is just a piece of glass also opens up the possibility of solar windows.