Garden Light Turned Mesh Network Node

January 21, 2024 by Danie Conradie 11 Comments

We love a good deal, especially when it comes to scavenging parts for projects. Cheap outdoor solar lights are more than just garden accessories; they’re a handy source of waterproof enclosures, solar panels and batteries. This is demonstrated by [Tavis], who turned one such light into a Meshtastic LoRa communication node.

Solar Light With Meshtastic node inside — Where there’s an antenna, there’s a radio

A nice feature on this specific $15 Harbor Breeze Solar LED is the roomy solar panel enclosure with integrated 18650 battery holder, allowing for easy battery swaps. [Tavis] was able to easily fit the RAKwireless modular dev board, and wire it into the light’s charging circuit. The cheap circuit is likely not the most efficient, but will probably get the job done. It’s always possible to just swap it out with a better charging board. [Tavis] also added an external antenna by using a panel-mount SMA pigtail connector.

The Meshtastic project is all about enabling text-only communications through LoRa-based mesh networks, built using off-the-shelf devices and development boards that won’t break the bank. The project has seen some incredible growth, with people all over the world setting up their own networks.

It’s not the first time we’ve seen garden lights get used in project. We’ve seen MQTT added to a PIR solar light with some clever power saving circuitry, and as a power source for Attiny85-based projects.

Sun On The Run: Diving Into Solar With A Mobile PV System

January 17, 2024 by Dan Maloney 36 Comments

For obvious reasons, there has been a lot of interest in small-scale residential solar power systems lately. Even in my neck of the woods, where the sun doesn’t shine much from October to April, solar arrays are sprouting up on rooftops in a lot of local neighborhoods. And it’s not just here in suburbia; drive a little way out into the country or spend some time looking around in Google maps and it won’t take long to spy a sizable array of PV panels sitting in a field next to someone’s ranch house or barn.

Solar has gotten to the point where the expense of an installation is no longer a serious barrier to entry, at least if you’re willing to put in a little sweat equity and not farm the project out to a contractor. Doing it yourself requires some specialized tools and knowledge, though, over and above your standard suite of DIY skills. So, in the spirit of sharing hard-won knowledge, I decided to take the somewhat unusual step of writing up one of my personal projects, which has been in progress for a couple of years now and resulted in a solar power system that isn’t on a rooftop or a ground-mounted array at all, but rather is completely mobile: my solar trailer.

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Solar Chimneys: Viable Energy Solution Or A Lot Of Hot Air?

January 15, 2024 by Lewin Day 90 Comments

We think of the power we generate as coming from all these different kinds of sources. Oil, gas, coal, nuclear, wind… so varied! And yet they all fundamentally come down to moving a gas through a turbine to actually spin up a generator and make some juice. Even some solar plants worked this way, using the sun’s energy to heat water into steam to spin some blades and keep the lights on.

A solar updraft tower works along these basic principles, too, but in a rather unique configuration. It’s not since the dawn of the Industrial Age that humanity went around building lots of big chimneys, and if this technology makes good sense, we could be due again. Let’s find out how it works and if it’s worth all the bluster, or if it’s just a bunch of hot air.

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A series of plates and tubes sits in a tank of water. The plates are square with what looks to be a white coating.

Desalinating Water With The Sun

December 21, 2023 by Navarre Bartz 12 Comments

Getting fresh water from salt water can be difficult to do at any kind of scale. Researchers have developed a new method of desalinating water that significantly reduces its cost. [via Electrek]

By mimicking the thermohaline circulation of the ocean, the researchers from MIT and Shanghai Jiao Tong University were able to solve one of the primary issues with desalination systems, salt fouling. Using a series of evaporator/condenser stages, the seawater is separated into freshwater and salt using heat from the sun.

Evaporating water to separate it from salt isn’t new, but the researchers took it a step further by tilting the whole contraption and introducing a series of tubes to help move the water along and create eddy currents. These currents help the denser, saltier water move off of the apparatus and down deeper into the fluid where the salt doesn’t cause an issue with the device’s operation. The device should have a relatively long lifetime since it has no moving parts and doesn’t require any electricity to operate.

The researchers believe a small, suitcase-sized device could produce water for a family for less than the cost of tap water in the US. The (paywalled) paper is available from Joule.

If you’re curious about other drinking water hacks, check out this post on Re-Imagining the Water Supply or this previous work by the same researchers.

A dark brown bench suspended between two white and grey rectangular pillars. They are capped in the same brown HDPE material. Aluminum uprights go to a curved solar panel roof that looks somewhat similar to a paragliding chute. The bench is inside a clean-looking workshop with two large toolboxes against a plywood half wall.

Public Power, WiFi, And Shelter

December 13, 2023 by Navarre Bartz 39 Comments

In the US, we’re starting to see some pushback against hostile architecture, and in this vein, [benhobby] built a swanky public power and Wi-Fi access point.

This beautiful piece of infrastructure has 400 watts of solar plugged into 1.2 kWh of battery storage, and can dispense those electrons through any of its 120 VAC, USB-C, or USB-A plugs. The uprights are 3″ aluminum tubing attached to a base consisting of cinder blocks and HDPE panels. Power receptacles are housed in 3D printed enclosures with laser cut acrylic fronts. Three outdoor lights illuminate the stop at night, triggered by a photosensor.

The electronics and battery for the system, including the networking hardware, are in a weatherproof box on each side that can be quickly disconnected allowing field swaps of the hardware. Troubleshooting can then take place back at a workshop. One of the units has already been deployed and has been well-received. [benhobby] reports “There’s one in the wild right now, and it gets plenty of visitors but no permanent tenants.”

Want to see some more interesting hacks for public infrastructure? Check out this self-cooling bus stop, this bus bloom filter, or this public transit display.

Radio Emissions Over Sunspots Challenge Models Of Stellar Magnetism

December 1, 2023 by Donald Papp 1 Comment

Sustained radio emissions originating from high over a sunspot are getting researchers thinking in new directions. Unlike solar radio bursts — which typically last only minutes or hours — these have persisted for over a week. They resemble auroral radio emissions observed in planetary magnetospheres and some stars, but seeing them from about 40,000 km above a sunspot is something new. They don’t seem tied to solar flare activity, either.

The signals are thought to be the result of electron cyclotron maser (ECM) emissions, which involves how electrons act in converging geometries of magnetic fields. These prolonged emissions challenge existing models and ideas about how solar and stellar magnetic processes unfold, and understanding it better could lead to a re-evaluation of existing astrophysical models. Perhaps even leading to new insights into the behavior of magnetic fields and energetic particles.

This phenomenon was observed from our very own sun, but it has implications for better understanding distant stellar bodies. Speaking of our sun, did you know it is currently in it’s 25th Solar Cycle? Check out that link for a reminder of the things the awesome power of our local star is actually capable of under the right circumstances.

Solar Camera Built From Raspberry Pi

October 17, 2023 by Richard Baguley 29 Comments

Ever since an impromptu build completed during a two-week COVID-19 quarantine back in 2020, [Will Whang] has been steadily improving his Raspberry Pi solar photography setup. It integrates a lot of cool stuff: multiple sensors, high bandwidth storage, and some serious hardware. This is no junk drawer build either, the current version uses a $2000 USD solar telescope (an LS60M with 200mm lens) and a commercial AZ-GTi mount.

He also moved up somewhat with the imaging devices from the Raspberry Pi camera module he started with to two imaging sensors of his own: the OneInchEye and the StarlightEye, both fully open source. These two sensors feed data into the Raspberry Pi 4 Compute Module, which dumps the raw images into storage.

Because solar imaging is all about capturing a larger number of images, and then processing and picking the sharpest ones, you need speed. Far more than writing to an SD Card. So, the solution [Will] came up with was to build a rather complex system that uses a CF Express to NVME adapter that can keep up, but can be quickly swapped out.

Unfortunately, all of this hard work proved to be in vain when the eclipse came, and it was cloudy in [Wills] area. But there is always another interesting solar event around the corner, and it isn’t going anywhere for a few million years. [Will] is already looking at how to upgrade the system again with the new possibilities the Raspberry Pi 5 offers.

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