Google and the IEEE are giving away a million dollar prize to an individual or team, that can build the most efficient and compact DC to AC inverter. The goal is to design and build a 2kW inverter with a power density greater than 50W per cubic inch. To put that in perspective, conventional solar string inverters have power densities around 0.5-3W per cubic Inch, and microinverters around 5W per cubic Inch. So in other words, an order of magnitude more efficient than what we have now.
For the challenge, the inverter needs to convert 450VDC, with a 10 ohm series resistor simulating a solar array, to 240VAC @ 60Hz. Testing will consist of powering various resistive, inductive and capacitive loads ranging from 0-2kVA. The inverter is expected to regulate voltage within 5%, and frequency within 0.05%, while keeping the enclosure below 60 degrees C, and conforming to FCC Part 15 B (Unintentional radiators).
If you and/or your team can figure out the most efficient topology, switching frequency, novel use of high power wide bandgap (WBG) semiconductors, physically reduce the size of the input and output filters, and keep the whole thing running cool. Then get registered before the September 30, 2014 deadline. Inverters need to be functional and the results of this test procedure (PDF warning) sent in before July 22, 2015, then 18 finalists will be chosen to bring their inverters in person to a testing facility in the United States by October 21, 2015. The grand prize winner will be announced sometime in January, 2016
[Thanks for the tip Dmytro]
This Arduino power inverter would need a serious upgrade to enter. And speaking of entering challenges, it’s still not too late to enter our very own Hackaday Prize!
A looming, torturous summer is preparing to bear down on many of us, making this dirt-cheap swamp cooler build an attractive hack to fend off the heat.
Though this is a pretty standard evaporative cooler, the design comes together in a tidy and transportable finished product. The base is a ~$3, 5-gallon bucket from a local hardware store with its accompanying Styrofoam liner. Three 2 1/8″ holes carved into the side of both the bucket and liner will snugly fit some inch-and-a-half PVC pipe with no need for glue.
One last cut into the lid to seat a small desk fan rounds off this build—or you can chop into the styrofoam liner’s lid if you prefer. The video demonstrates using a 15W solar panel to run the fan, and we have to admit that the cooler seems to be an excellent low-cost build. It does, however, require a frozen gallon jug inside to pump out the chilled air for around 5-6 hours per jug. Maybe one of our frugal and mathematically-inclined readers can throw out some guesstimations for the cost of stocking the bucket with a jug of frozen water a couple times a day? Video after the jump.
Continue reading “A Low Cost, Solar-Powered Swamp Cooler”
If you’re looking for a last-minute Christmas present, you probably won’t have enough time to reproduce [Helmar’s] candle-powered Christmas card. He’s been working on it for a few years now, since his first prototype in 2010. Though he pieced together the original card with parts lying around his workshop, the most recent iteration looks like it belongs on the shelf in a store.
We last saw [Helmar’s] work two years ago, when he shared his Full Color Laser TV. This project is a bit more compact: the circuitry was printed with conductive ink on the cardstock, and all the required components are held together by conductive adhesive. To power the electronics, he decided against a battery and instead chose to embed a solar cell on the inside of the card. Placing a lit candle inside the open card provides enough juice for the exterior of the card to shine.
You can see a video of both the current and prototype versions of [Helmar’s] cards after the break.
Continue reading “CartoLucci: A Candle-Powered Christmas Card”
The folks at Manifold created their version of a tweeting bird feeder, and [Chad] wrote up a behind-the-scenes of their design. The goal is something we’ve seen before: When the bird lands to eat, take a picture and tweet it. In this case, they had some corporate money behind the project, and that allowed them to buy a nice solar panel and battery pack to keep the whole thing running.
The write-up is full of the experimentation that we all enjoy: They found that detecting motion through the camera feed wasn’t reliable, so they switched over to a PIR sensor. The PIR sensor was too sensitive to heat changes during the day, so they went with an ultrasonic rangefinder, but wind caused issues there. They finally came up with a solution which involves using two sensors to confirm motion. This seems a bit more complicated than it needs to be, but it works well for them.
We think it is nice to see companies getting behind quirky projects. All told, they spent dozens of hours on this, and they chose to give all of their findings back to the community in the form of thorough explanations and project diagrams. It would be nice to see more of this.
The weather in Colorado hasn’t been the best lately, so the birdhouse hasn’t been tweeting for a while. In our experience, a project that’s turned off is in the dangerous position of being scavenged for parts. Hopefully that isn’t the case here, and we will see it back in action when Spring starts.
While browsing through his local dollar store, [Taylor] came across a suspicious looking rock that, upon closer inspection, turned out to be a solar garden light. He scooped it up, took it home and cracked it open, modding it to function as a handheld solar flashlight.
Inside was a pathetically small 40mAh rechargeable battery, which he upgraded to a more standard rechargeable AA. The garden rock came pre-built with its own boost converter to kick up the voltage for the LED, but it was fairly dim. We’re guessing [Taylor] didn’t bother reverse engineering the converter and instead simply did some trial and error, but he managed to increase the LED’s brightness by slapping on a different value inductor.
As fun as it may be to have a rock for a flashlight, [Taylor] decided to cobble together a custom case out of a spare USB charger, making a battery holder and adding a pushbutton. The result is a handy solar flashlight that takes around five hours to charge. Check out some other custom lights: a lithium-powered PVC flashlight or one with a snazzier aluminum body and interchangeable heads.
Making keys is an amazing art with a lot of skill and technique involved. For those of you living in a post-apocalyptic world, [Dan] has a much simpler solution to the problems of having one too few keys for your locks and deadbolts – just cast them out of scrap with the power of the sun.
To make the mold of the key, [Dan] is using a two-piece plaster of paris mold. First, a thick layer of plaster is laid down in a small container and the key floated on the surface. After drying, sprues are put in with clay and the key embedded in a curing plaster block. After a few hours, a proper mold is created ready to receive molten metal.
The casting material is zinc – not as hard as the original steel key, but more than strong enough to turn a lock. This zinc is melted in a steel and plaster crucible with a gigantic fresnel lens.
As for the utility of this method of copying keys after the apocalypse, we’ll have to wonder how practical this method is. A giant fresnel lens isn’t just something you randomly find unless you’re going house to house looking for projection TVs, and finding a can of mold release after the end of the world is beyond credulity. That said, it’s a cool demonstration of metal casting that can be easily accomplished at home or at any hackerspace.
Continue reading “Making keys after the apocalypse”
If you have the space, and can build a tracking rig cheaply you’ll be able to get a lot more out of your solar panels. That’s because they work best when the sun’s rays are hitting them perpendicular to the surface and not at an angle. [Michael Davis] hit both of those stipulations with this mbed powered solar tracker.
At a garage sale he picked up an antenna motor for just $15. The thing was very old, but still wrapped in the original plastic. It’s beefy enough to move his panels, but he first needed a way to mount everything. After checking his angles he built a base out of wood and used galvanized water pipe as an axle. Cable clamps mate his aluminum angle bracket frame to the pipe. This frame holds the panels securely.
To track the sun he used two smaller cells which aren’t easy to pick out in this image. They are monitored by the mbed microcontroller which measures their output in order to point the assembly in the direction which has the most intense light. A couple of limit switches are included to stop the assembly when it reaches either side.
This technique of using small solar cells as the tracking sensors seems to work well. Here’s another project that took that approach.
Continue reading “Hardware store goods and an mbed combine help solar panels track the sun”