Solar vehicles are getting more and more common as the price of solar panels comes down, and the availability of motors and controllers for all of these vehicles rises. Making a solar-electric bike from a kit is one thing, but this solar-powered boat is a master class in hacking at all levels, from the solar drive train to the pontoons, and even the anchor.
[J Mantzel] has many videos about his boat on his channel, and watching them all will likely leave you wanting to build your own. He builds almost everything on his boat from scratch from things he has lying around. For example, the anchor was hand-built from fiberglass and then filled with concrete, and his steering system is a semi-complex system of ropes, pulleys, and shafts. Most of the boat’s shell was hand-built from fiberglass as well, and everything that can be repurposed is saved for later use.
The ten panels, batteries, inverter, and other miscellaneous part of the system were about half of the cost of the whole vessel, but he reports that he also uses the boat as a backup power source for his house, and can use the system to run other things like an electric chainsaw for example. He also uses the boat for camping and construction, and without having to worry about fuel it has been very useful to him.
If you get into the videos on the channel, you’ll find that this isn’t his only solar-powered boat. He recently completed a solar speedboat as well with a custom-built propeller that can really move across the water. His videos are apparently very popular as well, since they have been linked to repeatedly by readers in some of the recentsolar vehicle write-ups we’ve published.
Kayaks are a some of the most versatile watercraft around. You can fish from them, go on backpacking trips, or just cruise around your local lake for a few hours. They’re inexpensive, lightweight, don’t require fuel, and typically don’t require a license or insurance to operate. They also make a great platform for a solar-powered boat like this one with only 150 watts of panels and a custom-built motor with parts from an RC airplane.
[William Frasier] built his solar-powered kayak using three solar panels, two mounted across the bow of the boat using pontoons to keep them from dipping into the water, and the other mounted aft. Separating the panels like this helps to prevent all three of them being shaded at once when passing under bridges. They’re all wired in parallel to a 12V custom-built motor which is an accomplishment in itself. It uses custom-turned parts from teak, a rot-resistant wood, is housed in an aluminum enclosure, and uses an RC airplane propeller for propulsion.
Without using the paddles and under full sun, the kayak can propel itself at about 4 knots (7 kmh) which is comparable to a kayak being propelled by a human with a paddle. With a battery, some of the shading problems could be eliminated, and adding an autopilot to it would make it almost 100% autonomous.
His write-up is a pretty fun read, walking through his process, including an oscilloscope measurement showing how the capacitors’ voltage drops from 5.26 V to 3.5 V when the trigger is pressed, and interestingly, slowly recovers until it’s released a second later, when it then rises back to 4.5 V. He’s even included how he worked out of the panel’s maximum power point (MPP), which is what he was doing when the kids were first lured away to blow soap bubbles. But we’re sure Hackaday readers aren’t as easily distracted.
The resulting Solar Powered Bubble Blaster works quite well. At a starting voltage of 5.23 V, it runs for 15 seconds and then takes only a minute to recharge. Charged batteries would have had a longer runtime but take longer to recharge, an important point when trying to keep kids interested. See it in action in the video below.
Every scrap of power is precious when it comes to power harvesting, and working with such designs usually means getting cozy with a microcontroller’s low-power tricks and sleep modes. But in the case of the Ultra Low Power Energy Harvester design by [bobricius], the attached microcontroller doesn’t need to worry about managing power at all — as long as it can finish its job fast enough.
The idea is to use solar energy to fill a capacitor, then turn on the microcontroller and let it run normally until the power runs out. As a result, a microcontroller may only have a runtime in the range of dozens of microseconds, but that’s just fine if it’s enough time to, for example, read a sensor and transmit a packet. In early tests, [bobricius] was able to reliably transmit a 16-bit value wirelessly every 30 minutes using a small array of photodiodes as the power supply. That’s the other interesting thing; [bobricius] uses an array of BPW34 photodiodes to gather solar power. The datasheet describes them as silicon photodiodes, but they can be effectively used as tiny plastic-enclosed solar cells. They are readily available and can be arranged in a variety of configurations, while also being fairly durable.
Charging a capacitor then running a load for a short amount of time is one of the simplest ways to manage solar energy, and it requires no unusual components or fancy charge controllers. As long as the load doesn’t mind a short runtime, it can be an effective way to turn even indoor light into a figuratively free power source.
Earlier, we had covered setting up an AS3935 lightning detector module. This detector picks up radio emissions, then analyzes them to determine if they are a lightning strike or some other radio source. After collecting some data, it outputs the estimated distance to the incoming storm front.
But that only gets you halfway there. The device detects many non-lightning events, and the bare circuit board is lacking in pizzazz. Today I fix that by digging into the detector’s datasheet, and taking a quick trip to the dollar store buy a suitable housing. The result? A plastic plant that dances when it’s going to rain! Continue reading “Storm Detector Modules: Dancing in the Rain”→
Last time, we covered storing and charging a 3000 Farad supercapacitor to build a solar-powered, portable spot welder. Since then, I’ve made some improvements to the charging circuit and gotten it running. To recap, the charger uses a DC-DC buck converter to convert a range of DC voltages down to 2.6 V. It can supply a maximum of 5 A though, and the supercapacitor will draw more than that if allowed to.
After some failed attempts, I had solved that by passing the buck converter output through a salvaged power MOSFET. A spare NodeMCU module provided pulse width modulated output that switched the MOSFET on for controlled periods of time to limit the charging current. That was fine, but a constant-voltage charger really isn’t the right way to load up a capacitor. Because the capacitor plates build up a voltage as it charges, the current output from a constant-voltage charger is high initially, but drops to a very low rate in the end.
Like many people who have a solar power setup at home, [Jeroen Boeye] was curious to see just how much energy his panels were putting out. But unlike most people, it just so happens that he’s a data scientist with a deep passion for programming and a flair for visualizations. In his latest blog post, [Jeroen] details how his efforts to explain some anomalous data ended with the discovery that his solar array was effectively acting as an extremely low-resolution camera.
It all started when he noticed that in some months, the energy produced by his panels was not following the expected curve. Generally speaking, the energy output of stationary solar panels should follow a clear bell curve: increasing output until the sun is in the ideal position, and then decreasing output as the sun moves away. Naturally cloud cover can impact this, but cloud cover should come and go, not show up repeatedly in the data.
[Jeroen] eventually came to realize that the dips in power generation were due to two large trees in his yard. This gave him the idea of seeing if he could turn his solar panels into a rudimentary camera. In theory, if he compared the actual versus expected output of his panels at any given time, the results could be used as “pixels” in an image.
He started by creating a model of the ideal energy output of his panels throughout the year, taking into account not only obvious variables such as the changing elevation of the sun, but also energy losses through atmospheric dispersion. This model was then compared with the actual power output of his solar panels, and periods of low efficiency were plotted as darker dots to represent an obstruction. Finally, the plotted data was placed over a panoramic image taken from the perspective of the solar panels. Sure enough, the periods of low panel efficiency lined up with the trees and buildings that are in view of the panels.