[Phillip] and the crew at Voltaic Systems took a look at the Sunnan solar powered desk lamp from IKEA a while back, and while they thought it was pretty useful, there were definitely some things they wanted to change.

First on their list of revisions was to increase the capacity of the stock battery pack. Taking the lamp apart and unscrewing the pack’s lid revealed a set of 3 AA cells, which they swapped out for higher-capacity models with more than double the watt-hour rating.

A beefed up battery is a good start, but the lamp’s tiny solar panel has no hope of topping off the batteries outside of Death Valley. To ensure that they get a nice full charge, a small jack was wired into to the battery pack, allowing the group to connect any size external solar panel they pleased.

Finally, [Phillip] and Co. wanted the ability to charge an iPad2 from the lamp’s battery pack. They hacked in a small USB connector and a slightly modified MintyBoost board to provide a little extra juice to their tablet.

While they are still testing the modifications, they say that everything is working nicely, citing that the extra battery capacity and charging abilities are a great addition.

Although we’ve featured many chicken-related hacks here, this chicken coop features a solar-powered door to save one from having to open up the coop in the morning.  As [chrisatronics] puts it “keeping chickens has one major drawback: You have to get up with them in the early morning and open the door at the coop. Everyday. Including Sundays and holidays.” This would help explain why so many people seem to be hacking their coops.

Solar power may be an interesting idea in itself, but when coupled with the fact that a chicken coop isn’t necessarily near a power supply, this becomes a very expedient solution. Controlling the setup is a MSP430 microcontroller (programming featured here for Linux) with a salvaged windshield wiper gearmotor. [Chrisatronics] did a great job writing this hack up, so if you want to try this yourself, make sure to check out the article.

Also, don’t forget to check out the video after the break for the ‘coop in action!

For another way to open your coop in the morning, check out this hack. Or combine it with a methane generator, and you’ll be on your way to energy independence in no time!

via [430h.com]

Make your next project solar-powered with this charging circuit. It’s completely through-hole, and there are no microcontrollers that need to be flashed. If you can source parts and are handy with a soldering iron building this will be a breeze.

Both the maximum system voltage and the low voltage drop out are configurable. After assembly, you just need to attach a regulated power supply to the load terminals. Tune the power supply to the max voltage and turn a potentiometer until an LED comes on, then repeat the process for the drop out voltage. Board artwork for the two-sided PCB and a schematic are available from the page linked at the top. If you’re not into etching your own circuit boards you can buy one for around $10.

[Thanks Murray]

[Frits] has been working on an solar panel heliostat (in Dutch, check out the translated page here).

The heliostat uses a small PICAXE to control the motor, along with an DS1307 real-time clock to make sure the motors start at dawn. Instead of using optical encoders or magnetic sensors, the angle of the heliostat is measure with a pot attached to the drive shaft. [Frits] did a lot of data collection to figure out that this method is accurate to about 1 degree – just fine for something that doesn’t need to be exact.

According to [Frits] this heliostat will put out 12 to 50 percent more electricity than a fixed panel. Although the build does seem a little bulky, putting it on a  house with a roof pitch of 23.5° would greatly reduce the horizontal profile.

A video of a solar panel rotating at 15 degrees/hour isn’t that interesting, so [Frits] posted a clip of 6 mirrors slewing around fairly fast to demonstrate his system. Check it out after the break.

[Markus Kayser] built an amazing solar powered SLS printer, but instead of using lasers and powdered plastics his machine uses the power of the sun to heat sand into complex shapes.

[Markus]‘ printer uses the same concept as his earlier solar cutter – burning things with a magnifying glass. Interestingly, the printer isn’t controlled with stepper motors and reprap electronics – it’s completely cam driven. The solar panels only power the motor attached to the frame moving on bearings made from skateboard wheels.

We’d guess that [Markus] is using a little more than 2 square meters of Fresnel lenses in his project. Since solar irradiance is about 120 W/m² (PDF warning), [Markus] is concentrating a lot of energy onto a point the size of a quarter, which would be necessary to heat up sand to its 1500° C melting point. The resolution isn’t what you could get with a laser, but [Markus] was able to print an amazing bowl along with other complex 3d shapes.

Check out [Markus]‘ video of the solar sinter printer after the break. There’s also a video of his previous experiment with the solar cutter.

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.