Using The Sun To Beat The Heat

Hackaday Solar Hacks -

It’s practically May, and that means the sweltering heat of summer is nearly upon us. Soon you’ll be sitting outside somewhere, perhaps by a lake, or fishing from a canoe, or atop a blanket spread out on the grass at a music festival, all the while wishing you had built yourself a solar-powered personal air conditioner.

[Nords] created his from a large insulated beverage vessel. The imbibing spout offers a pre-made path to the depths of said vessel and the heart of this build, the ice water refrigerant. [Nords] fashioned a coil out of copper tubing to use as a heat exchanger and strapped it to the fan that performed best in a noise-benefit analysis.

A small USB-powered submersible pump moves the ice water up through the copper tubing. Both the pump and the fan run off of a 5V solar panel and are connected with a USB Y cable, eliminating the need for soldering. Even if you spend the summer inside, you could still find yourself uncomfortably warm. Provided you have access to ice, you could make this really cool desktop air conditioner.

[via Embedded Lab]

Filed under: lifehacks, solar hacks

Modern Spin on an Old Technology

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It seems that the longer a technology has been around, the more likely it is that all of the ideas and uses for that technology will be fleshed out. For something that’s been around for around 5500 years it must be especially rare to teach an old dog new tricks, but [Sebastian] has built a sundial that’s different from any we’ve ever seen.

Once done with all of the math for the sundial to compute its angles and true north based on his latitude and longitude, [Sebastian] used Autodesk Inventor to create a model. From there it was 3D printed, but the interesting part here is that the 3D printer allowed for him to leave recesses for numbers in the sundial. The numbers are arranged at such angles inside the sundial so that when it’s a particular hour, the number of the hour shines through the shadow of the sundial which creates a very unique effect. This would be pretty difficult to do with any machine tools but is easily accomplished via 3D printing.

[Sebastian] wanted a way to appreciate the beauty of time, and he’s certainly accomplished that with this new take on  the sundial! He also wonders what it would be like if there was a giant one in a park. This may also be the first actual sundial build we’ve featured. What does that mean? Check out this non-pv, sun-powered clock that isn’t a sundial.

Thanks to [Todd] for the tip!

Filed under: solar hacks

Solar Charge Controller Improves Efficiency of Solar Panels

Hackaday Solar Hacks -

The simplest and easiest way to charge a battery with a solar panel is to connect the panel directly to the battery. Assuming the panel has a diode to prevent energy from flowing through it from the battery when there’s no sunlight. This is fairly common but not very efficient. [Debasish Dutta] has built a charge controller that addresses the inefficiencies of such a system though, and was able to implement maximum power point tracking using an Arduino.

Maximum power point tracking (MPPT) is a method that uses PWM and a special DC-DC converter to match the impedance of the solar panel to the battery. This means that more energy can be harvested from the panel than would otherwise be available. The circuit is placed in between the panel and the battery and regulates the output voltage of the panel so it matches the voltage on the battery more closely. [Debasish] reports that an efficiency gain of 30-40% can be made with this particular design.

This device has a few bells and whistles as well, including the ability to log data over WiFi, an LCD display to report the status of the panel, battery, and controller, and can charge USB devices. This would be a great addition to any solar installation, especially if you’ve built one into your truck.

This is [Debasish]’s second entry to The Hackaday Prize. We covered his first one a few days ago. That means only one thing: start a project and start documenting it on

Filed under: solar hacks, The Hackaday Prize

Nocturnal Solar Light Bulb Saves Your Lungs

Hackaday Solar Hacks -

India has a bit of a problem with electricity. In fact, over 74 million rural households live without power altogether. Instead they rely on burning fuel for light — and coincidentally, inhaling harmful smoke. Not to mention fuel isn’t cheap. [Debasish Dutta] wants to change this — so he came up with yet another solar powered light that is a low-cost alternative.

It’s a very simple light made out of a cheap Tupperware container, a 2V solar panel, a white LED, a rechargeable AA or AAA battery, a photo diode and a Joule thief (voltage boosting IC). One day of charging can provide approximately 20-22 lumens for the entire night of operation. While it doesn’t seem like much, a typical kerosene lamp puts out less than half that brightness.

And with the photo diode, it automatically turns on at night, and off during the day. A coat hanger doubles as both a stand for charging, and a hook for hanging it at night.

[Dabasish] says this is just the beginning and has a website dedicated to creating green energy and sharing it with the world. Video below.

Filed under: solar hacks, The Hackaday Prize

Hippie-Redneck Solar-Heated Swimming Pool Slash Hot Tub

Hackaday Solar Hacks -

In need of a jacuzzi to complete your backyard but just don’t have the cash? Need a swimming pool for the little ones but tired of the cheap plastic ones popping and leaking all over the place? Look no further than [inexplorata]’s self-explanatory “Hippie-Redneck Solar-Heated Kiddo Swimmin’ Pool And Hot Tub“.

The pool uses a six-foot-diameter metal stock tank, provided by a neighbor. After some liberal use of JB Weld, the tank functions as a makeshift pool on the cheap, but the magic doesn’t end there. [inexplorata] found a solar thermal water heater that someone was getting rid of and snagged it to heat up the water, which is almost a necessity for most parts of the Northern Hemisphere right now.

A sump pump in a bucket handles water circulation, and [inexplorata] points out that the single water heater is more than enough to keep the water nice and warm (“hot enough to poach a rhino” is the scientific term used on the project page) so if you’ve got the means, this might be a welcome addition to the backyard! The build was posted on Reddit, the users of which had some helpful suggestions for improving the pool if you want to tackle this yourself. If you don’t have a solar thermal water heater, you could always make one of those too.

Filed under: solar hacks
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