2022 Hackaday Prize: Get Your Planet-Friendly Power On!

Time flies! This weekend marks the end of the first stage of the 2022 Hackaday Prize, and your chance to enter your alternative-energy projects. There are ten $500 prizes up for grabs, and there’s still time to whip up a project page over on Hackaday.io to showcase it.

In this round, we’re looking for projects that harvest their own energy — solar, wind, heat, vibration, you name it — or projects that make it easier to collect, store, or use renewable energy. Whether this is microwatts or megawatts, the scale of the project is up to you! As long as it’s using or making it easier to use clean energy, we want to see it.

So far, we’ve seen some great projects, ranging from a optimizes the tilt angle of a home solar installation to a demonstration of using a new type of lithium-ion capacitor to add solar power to smaller projects. We really love [MartMet]’s simple Bluetooth thermometer hack, which adds a supercapacitor and solar cell to an outdoor thermometer, and then uses hacked firmware to log the charge status over a year of use! We’re suckers for good data.

The sun is not the only game in town, though. There are a surprising number of projects based on human energy production in emergency situations, from cranking to shaking. Thermionic converters were new to us, but we love explorations of fringe tech. Other traditional favorites like wind and water may make more sense for larger applications. And don’t forget how you’re going to store all this juice you’ve collected.

In short, we’ve got a bunch of great entries, but we’re still missing yours! There’s no minute like the last minute: if you’ve done some work in clean or renewable energy, set yourself up a Hackaday.io project page now. You’ll help make all our projects cleaner, and stand a good chance of taking home some real money to boot!

Once we’ve handled power, the next round is “Reuse, Recycle, Revamp” where any tech that uses recycled parts or facilitates reuse, repair, or recycling is fair game!

Tracking Maximum Power Point For Solar Efficiency

In days of yore when solar panels weren’t dirt cheap, many people (and even large energy companies) used solar trackers to ensure their panels were always physically pointed at the sun to make sure they harvested every watt of energy possible. Since the price of panels has plummeted, though, it’s not economical to install complex machines to track the sun anymore. But all solar farms still track something else, called the Maximum Power Point (MPP), which ensures that even stationary panels are optimized for power production.

While small MPP trackers (MPPT) are available in solar charge controllers in the $200 range that are quite capable for small off-grid setups, [ASCAS] aka [TechBuilder] decided to roll out an open source version with a much lower price tag since most of the costs of these units are in R&D rather than in the actual components themselves. To that end, the methods that he uses for his MPPT are essentially the same as any commercial unit, known as synchronous buck conversion. This uses a specially configured switch-mode power supply (SMPS) in order to match the power output of the panels to the best power point for any given set of conditions extremely rapidly. It even works on many different battery configurations and chemistries, all configurable in software.

This build is incredibly extensive and goes deep into electrical theory and design choices. One design choice of note is the use of an ESP32 over an Arduino due to the higher resolution available when doing analog to digital conversion. There’s even a lengthy lecture on inductor core designs, and of course everything on this project is open source. We have also seen the ESP32 put to work with MPPT before, although in a slightly less refined but still intriguing way.

Thanks to [Sofia] for the tip!

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The Cult Of Really Low-Power Circuits: Scrounging, Sipping, And Seeing Power

If you’ve ever tried to make a really low-power circuit — especially one that runs on harvested power — you have probably fallen into at least a few of the many traps that await the unwary in this particular realm of electronic design. Well, Dave Young has been there, seen the traps, and lived to tell about it. In these territories, even “simple” systems can exhibit very complex, and sometimes downright confusing behavior when all possible operating conditions are considered. In his 2019 Hackaday Superconference talk: Scrounging, Sipping, and Seeing Power — Techniques For Planning, Implementing, And Verifying Off-Grid Power Systems, Dave discusses a number of these issues, how they interplay with low-power designs, and tricks he’s collected over the years to design and, more importantly, test these deceptively simple systems.

Dave is an electrical engineer and his company, Young Circuit Designs, has worked in the test and measurement, energy, and low-power consumer industries. We were lucky to have him share some of his 15 years of experience on the Supercon stage this past November, specifically discussing devices powered from harvested energy, be it wave energy (think oceans not RF), thermal energy, or solar. The first lesson is that in these systems, architecture is key. Digging deeper, Dave considers three aspects of the architecture, as mentioned in the talk title: scrounging, sipping, and seeing power.

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ESP32 Makes Great MPPT Controller In Low-Cost Solar Installation

Solar power projects have become, in general, a matter of selecting components like panels and batteries, hooking them together with industry-standard connectors, and sitting back to watch the free electricity flow. As such, solar projects have become a bit boring, so it’s not often we see one that attracts our attention the way this dirt-cheap open-source solar project does.

The backstory on [Tim O’Brien]’s DIY off-grid PV system starts with his desire to charge his eWheel, which amounts to a battery-powered standing unicycle. They look like a fun option for getting around an urban environment if you have the requisite degree of coordination, which we clearly lack. But charging something like that or an eBike is a great use case for solar, especially since [Tim] happened upon a 450W PV panel on the cheap. Sadly, the panel was a commercial unit, and compatible off-the-shelf MPPT, or maximum power-point tracking, controllers are expensive.

His solution was to build his own controller using a cheap DC-DC converter that just so happens to have serial remote control. An ESP32 monitors the panel voltage and controls the buck converter to run whatever he wants. When he’s not charging his eWheel, the system runs his laptop and router. As a bonus, the ESP32 talks to IoT services like Adafruit.io and Thingspeak, allowing him to track MPPT data without shipping it off to parts unknown.

While we appreciate a DIY MPPT controller and like [Tim]’s build, we feel like the documentation needs a bit of fleshing out. With solar installations, the devil is in the details, and not addressing seemingly mundane issues like cable routing and connector installation can lead to disaster.

Soaring With The Sun: 4 Years Of Solar RC Planes

Many of us have projects that end up spanning multiple years and multiple iterations, and gets revisited every time inspiration strikes and you’ve forgotten just how much work and frustration the previous round was. For [Daniel Riley] AKA [rctestflight] that project is a solar powered RC plane which to date spans 4 years, 4 versions and 13 videos. It is a treasure trove of information collected through hard experience, covering carbon fibre construction techniques, solar power management and the challenges of testing in the real world, among others.

Solar Plane V1 had a 9.5 ft / 2.9 m carbon fibre skeleton wing, covered with transparent film, with the fragile monocrystaline solar cells mounted inside the wing. V1 experienced multiple crashes which shattered all the solar cells, until [Daniel] discovered that the wing flexed under aileron input. It also did not have any form of solar charge control. V2 added a second wing spar to a slightly longer 9.83 ft / 3 m wing, which allowed for more solar cells.

Solar Plane V3 was upgraded to use a single hexagonal spar to save weight while still keeping stiff, and the solar cells were more durable and efficient. [Daniel] did a lot of testing to find an optimal solar charging set-up and found that using the solar array to charge the batteries directly in a well-balanced system actually works equally well or better than an MPPT charge controller.

V4 is a departure from the complicated carbon fibre design, and uses a simple foam board flying wing with a stepped KF airfoil instead. The craft is much smaller with only a 6 ft / 1.83 m wingspan. It performed exceptionally well, keeping the battery fully charged during the entire flight, which unfortunately ended in a crash after adjusting the autopilot. [Daniel] suspects the main reasons for the improved performance are higher quality solar panels and the fact that there is no longer film covering the cells.

We look forward to seeing where this project goes! Check out Solar Plane V4 after the break.

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Tacking Against The Sun: Flying A Batteryless Solar RC Plane Is Almost Like Sailing

Flying on the power of the sun is definitely not a new idea, but it usually involves a battery between the solar panels and the propulsion system. [ukanduit] decided to lose the battery completely and control the speed of the motor with the output of the solar panels. This leads to some interesting flying characteristics, almost akin to sailing.

When a load tries to draw more current than a solar panel can provide, its output falls dramatically, so [ukanduit] had to take this into account. Using a ATTiny85, he built a MPPT (Maximum Power Point Tracker) unit that connects between the RC receiver and the motor speed controller. It monitors the output of the panels and modulates the speed of the motor accordingly, while ensuring that there is always enough power to run the servos and receiver. The airframe (named the Solar Bear) is a small lightweight flying wing, with a balsa and carbon fibre frame covered with clear film, with the solar cells housed inside the wing. Since the thrust of the motor is directly proportional to how much sunlight hits the top of wings, it requires the pilot to “tack” against the sun and use momentum to quickly get through turns before orienting into the sun again.

If you want to build your own controller, the schematics and software is up on RC Groups. Check out the Solar Bear in action, flown here by [AJWoods].

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High Efficiency, Open-Sourced MPPT Solar Charger

A few years ago, [Lukas Fässler] needed a solar charge controller and made his own, which he has been improving ever since. The design is now mature, and the High Efficiency MPPT Solar Charger is full of features like data logging, boasts a 97% efficiency over a range of 1 to 75 Watts, and can be used as a standalone unit or incorporated as a module into other systems. One thing that became clear to [Lukas] during the process was that a highly efficient, feature-rich, open-sourced hardware solution for charge controllers just didn’t exist, at least not with the features he had in mind.

Data logging and high efficiency are important for a charge controller, because batteries vary in their characteristics as they recharge and the power generated from things like solar panels varies under different conditions and loads. An MPPT (Maximum Point Power Tracking) charger is a smart unit optimized to handle all these changing conditions for maximum efficiency. We went into some detail on MPPT in the past, and after three years in development creating a modular and configurable design, [Lukas] hopes no one will have to re-invent the wheel when it comes to charge controllers.