The other issue is that solar cells have a guanteed life expectancy of about 25 years, with average efficiency losses of 0.5% per year. If replacement begins after 25 years, time is running out for all the panels that were installed during the early 2000s boom. The International Renewable Energy Agency (IREA) projects that by 2050, we’ll be looking at 78 million metric tons of bulky e-waste. The IREA also believe that we’ll be generating six million metric tons of new solar e-waste every year by then, too. Unfortunately, there are hardly any measures in place to recycle solar panels, at least in the US.
How are solar panels made, anyway? And why is it so hard to recycle them? Let’s shed some light on the subject.
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].
When featuring cool hacks repurposing one thing for something else, we prefer to focus on what we could get our hands on and replicate for ourselves. Not this one, though, as nobody else has the misfortune of being responsible for 2,000 square kilometers (772 square miles) of radioactive contaminated land like the government of Ukraine. Trying to make the best of what they have, they’ve just launched a pilot program working to put up solar power farms inside the Chernobyl Exclusion Zone.
This is sure to invite some jokes in the comments section, but the idea has merit. Thirty years of weather has eroded the worst aftermath of the Chernobyl explosion. That area is no longer immediately lethal and people have been making short visits. Spanning from safety inspectors, to scientists, to curious adventurers with questionable judgement making television shows. Supposedly, by following rules on what not to do, it’s possible to keep radiation exposure of a short visit down to the level experienced by frequent fliers. But that’s still too much radiation for long-term stay. That means no homes, office parks, or factories. No agriculture either, as plants and animals grown in the area should not be eaten.
Well, next to the defunct power plant is the electric distribution infrastructure it used to feed into, and photovoltaic power generation requires little human oversight. Some maintenance will be required, but hopefully someone has worked out how to keep maintenance workers’ cumulative exposure to a minimum. And if this idea pans out, clean renewable energy would start flowing from the site of one of the worst ecological disasters of our era. That makes it a worthwhile hack on a grand scale.
Invariably when we write about living on Mars, some ask why not go to the Moon instead? It’s much closer and has a generous selection of minerals. But its lack of an atmosphere adds to or exacerbates the problems we’d experience on Mars. Here, therefore, is a fun thought experiment about that age-old dream of living on the Moon.
Inhabiting Lava Tubes
The Moon has even less radiation protection than Mars, having practically no atmosphere. The lack of atmosphere also means that more micrometeorites make it to ground level. One way to handle these issues is to bury structures under meters of lunar regolith — loose soil. Another is to build the structures in lava tubes.
A lava tube is a tunnel created by lava. As the lava flows, the outer crust cools, forming a tube for more lava to flow through. After the lava has been exhausted, a tunnel is left behind. Visual evidence on the Moon can be a long bulge, sometimes punctuated by holes where the roof has collapsed, as is shown here of a lava tube northwest from Gruithuisen crater. If the tube is far enough underground, there may be no visible bulge, just a large circular hole in the ground. Some tubes are known to be more than 300 meters (980 feet) in diameter.
Lava tubes as much as 40 meters (130 feet) underground can also provide thermal stability with a temperature of around -20°C (-4°F). Having this stable, relatively warm temperature makes building structures and equipment easier. A single lunar day is on average 29.5 Earth days long, meaning that we’ll get around 2 weeks with sunlight followed by 2 weeks without. During those times the average temperatures on the surface at the equator range from 106°C (224°F) to -183°C (-298°F), which makes it difficult to find materials to withstand that range for those lengths of time.
In The Martian we saw what kind of hacking was needed to stay alive for a relatively short while on Mars, but what if you were trying to live there permanently? Mars’ hostile environment would affect your house, your transportation, even how you communicate. So here’s a fun thought experiment about how you’d live on Mars as part of a larger community.
Not Your Normal House
Radiation on Mars comes from solar particle events (SPE) and galactic cosmic radiation (GCR). Mars One, the organization planning one-way trips to Mars talks about covering their habitats in several meters of regolith, a fancy word for the miscellaneous rocky material covering the bedrock. Five meters provides the same protection as the Earth’s atmosphere — around 1,000 g/cm2 of shielding. A paper from the NASA Langley Research Center says that the largest reduction comes from the top 15 to 20 cm of regolith. And so our Mars house will have an underlying structure but the radiation protection will come from somewhere between 20 cm to a few meters of regolith. Effectively, people will be living underground.
On Earth, producing water and air for your house is not something you think of doing, let alone disposing of exhaled CO2. But Mars houses will need systems for this and more.
There are two types of people: ones with green thumbs, and ones that kill their cacti because they forgot to water them for over a year. Sadly, we are of the latter group. We currently have a resilient spider plant that looks like it could use more sun. Now there’s a way for it to catch those rays wherever they may shine, thanks to [Dot Matrix] of Instructables. She made a mobile planter that actively seeks out sunlight.
The planter’s base was made of plywood, topped with fake grass and a watering can to hold the plant. Anything above the planter base can be modified to whatever desired aesthetic. A CRT planter may be too heavy, but there are countless ways to personalize it. [Dot] used an Afinia 3D printer to make various mounts and brackets with ABS plastic. The planter was controlled by an Arduino Micro and used a pair of 0.5W solar panels and Parallax PING))) sensors to decide how it should move from its current position. If the planter would fall or hit an object moving forward, it would reverse and turn on wheels powered by Parallax continuous rotation servos. It would evaluate its new position, repeating the process if it was in danger. Once the planter was safe, it used the solar panels to detect the most sunlight: the sum of the panels determines the area’s brightness while the individual panels’ readings were used to move the planter towards a brighter area. The sun-seeking continued until the sunniest spot was found (defined in the code). Here, the planter remained idle for 10 minutes before restarting the process.
We think [Dot’s] planter is a fun way to keep plants happy and healthy in spite of us. See a video of the planter after the break.
Solar panels are a great, sustainable addition to your home’s energy scheme. They’re bound to get dirty, but they can’t withstand harsh chemicals and still be effective. While there are companies that will come out and clean your installation a few times a year, the service is a recurring cost that adds up quickly. With Scrobby, his entry into The Hackaday Prize, [Stefan] sought to build a highly affordable and sustainable solution that, after installation, requires no dangerous trips back up to the roof.
Scrobby is solar-powered and cleans using rainwater. The user can set and alter the cleaning schedule over Bluetooth from their phone. [Stefan]’s prototype was built around a Teensy 3.0, but he will ultimately use custom boards based on the Freescale KL26. In addition to the Bluetooth module, there are six ultrasonic sensors, rain and temperature sensors, and motor-driven spools for tethered movement.
Make the jump to see Scrobby get his prototype bristles installed and show off his abilities in [Stefan]’s demo video. To register for updates, check out Scrobby’s website. If you hurry, you can donate to Scrobby’s Kickstarter campaign. The question is, who will clean Scrobby’s solar panels?