solar panel

47 Articles

Black and white photo of Evertop computer on desk

The Evertop: A Low-Power, Off-Grid Solar Gem

April 23, 2025 by 32 Comments

When was the last time you saw a computer actually outlast your weekend trip – and then some? Enter the Evertop, a portable IBM XT emulator powered by an ESP32 that doesn’t just flirt with low power; it basically lives off the grid. Designed by [ericjenott], hacker with a love for old-school computing and survivalist flair, this machine emulates 1980s PCs, runs DOS, Windows 3.0, and even MINIX, and stays powered for hundreds of hours. It has a built-in solar panel and 20,000mAh of battery, basically making it an old-school dream in a new-school shell.

What makes this build truly outstanding – besides the specs – is how it survives with no access to external power. It sports a 5.83-inch e-ink display that consumes zilch when static, hardware switches to cut off unused peripherals (because why waste power on a serial port you’re not using?), and a solar panel that pulls 700mA in full sun. And you guessed it – yes, it can hibernate to disk and resume where you left off. The Evertop is a tribute to 1980s computing, and a serious tool to gain some traction at remote hacker camps.

For the full breakdown, the original post has everything from firmware details to hibernation circuitry. Whether you’re a retro purist or an off-grid prepper, the Evertop deserves a place on your bench. Check out [ericjenott]’s project on Github here.

Hot Water Heater Hacked To Run On Solar Juice

September 6, 2024 by 41 Comments

It’s 2024, and there’s no getting around it. Grid energy is expensive. [Darrell] realized that a lot of his money was going on water heating, and he came up with a neat solution. What if he could hack in some solar power to slash his bills at a minimum of fuss? It worked so well for him, he’s whipped up a calculator to help others do the same.

[Darrell]’s idea was simple enough. He hooked up solar panels to just the bottom heating element of his hot water heater. This cut his power bill in half. His calculator is now up at pvh20.com, and it’s designed to help you figure out if it’s feasible for you. It takes into account your location, local power prices, and the amount of sun your area tends to get on a regular basis. It also takes into account the solar panels you intend to use and your water heater to determine how many panels you’ll need for properly hot water. Key all that in, and you’re well on your way to speccing a decent solar hot water setup. From there you’ll just need to buy the right stuff and wire it all up properly.

If you live in an area where the sun shines freely and the power is more expensive than printer ink, this could be a project well worth pursuing. Cheaper hot water is a grand thing, after all. [Darrell’s] calculator is really only the first step, and it doesn’t deal with the practicalities of installation, but that’s half the fun of a good project, right? Happy hacking!

The Sunchronizer Keeps Your Solar Panel Aligned

August 15, 2024 by 34 Comments

In the past few years, the price-per-watt for solar panels has dropped dramatically. This has led to a number of downstream effects beyond simple cost savings. For example, many commercial solar farms have found that it’s now cheaper to install a larger number of panels in fixed positions, rather than accepting the extra cost, maintenance, and complexity of a smaller number panels that use solar tracking to make up the difference. But although this practice is fading for large-scale power production, there are still some niche uses for solar tracking. Like [Fabian], if you need to maximize power production with a certain area or a small number of panels you’ll wan to to build a solar tracker.

[Fabian]’s system is based on a linear actuator which can tilt one to four panels (depending on size) in one axis only. This system is an elevation tracker, which is the orientation generally with respect to latitude, with a larger elevation angle needed in the winter and a lower angle in the summer. [Fabian] also designs these to be used in places like balconies where this axis can be more easily adjusted. The actuator is controlled with an ESP32 which, when paired with a GPS receiver, can automatically determine the sun’s position for a given time of day and adjust the orientation of the panel to provide an ideal elevation angle on a second-by-second basis. The ESP32 also allows seamless integration with home automation systems like SmartHome as well.

Although this system only tracks the sun in one axis right now, [Fabian] is working on support for a second axis which mounts the entire array on a rotating table similar to an automatic Lazy Susan. This version also includes a solar tracking sensor which measures solar irradiance in the direction the panel faces to verify that the orientation of the panel is maximizing power output for a given amount of sunlight. Tracking the sun in two axes can be a complicated problem to solve, but some solutions we’ve seen don’t involve any GPS, programming, or even control electronics at all.

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Autonomous Boat Plots Lake Beds

August 14, 2024 by 5 Comments

Although the types of drones currently dominating headlines tend to be airborne, whether it’s hobbyist quadcopters, autonomous delivery vehicles, or military craft, autonomous vehicles can take nearly any transportation method we can think of. [Clay Builds] has been hard at work on his drone which is actually an autonomous boat, which he uses to map the underwater topography of various lakes. In this video he takes us through the design and build process of this particular vehicle and then demonstrates it in action.

The boat itself takes inspiration from sailing catamarans, which have two hulls of equal size connected above the waterline, allowing for more stability and less drag than a standard single-hulled boat. This is [Clay]’s second autonomous boat, essentially a larger, more powerful version of one we featured before. Like the previous version, the hulls are connected with a solar panel and its support structure, which also provides the boat with electrical power and charges lithium-iron phosphate batteries in the hull. Steering is handled by two rudders with one on each hull, but it also employs differential steering for situations where more precise turning is required. The boat carries a sonar-type device for measuring the water depth, which is housed in a more hydrodynamic 3d-printed enclosure to reduce its drag in the water, and it can follow a waypoint mission using a combination of GPS and compass readings.

Like any project of this sort, there was a lot of testing and design iteration that had to go into this build before it was truly seaworthy. The original steering mechanism was the weak point, with the initial design based on a belt connecting the two rudders that would occasionally skip. But after a bit of testing and ironing out these kinks, the solar boat is on its way to measure the water’s depths. The project’s code as well as some of the data can be found on the project’s GitHub page, and if you’re looking for something more human-sized take a look at this solar-powered kayak instead.

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The PhotonPower Zero board laying on a desk surface

PhotonPower Zero For Effortless Solar Pi Zero Projects

April 2, 2024 by 2 Comments

A Pi Zero doesn’t need much to sustain itself, and it’s projects like the PhotonPower Zero that remind us of it its low appetite when we need this reminder most. The PhotonPower Zero board lets you power a Pi Zero board from a solar cell, with a LiIon backup, and a microcontroller for power management. Created by [David Murray], this board’s been a perfect solution for quite a few projects of his, and now he is sharing the design so that we can create outdoor-suited devices as easily as he’s been able to.

Tested for months in Australian summer and winter conditions alike, the design pulls no punches and has everything you might need. Like any self-respecting power addon, it has a management microcontroller for going as low-power as you’d like, communicating the battery data to the Pi Zero, and being able to safely shut it down when needed. If you fancy what this board does, [David Murray] tells you all, both in the video and in the associated posts!

One of the best parts about this board is that it’s fully open-source – schematics, KiCad PCB source files, and even 3D designs are available in the GitHub repo. You could source all the parts right now and build a fleet of solar-powered Zeros, and if you want the hard parts to be done for you, there’s a Kickstarter campaign that lets you get a PhotonPower Zero board without self-assembly. We’ve covered similar boards before – powering a Pi Zero isn’t lost art, and, there’s a lot to learn from this project specifically. Such boards are especially tempting, given that the latest Pi Zero W 2 is the most efficient Pi Zero to date – outdoor-capable 24/7 powered devices with a fair bit of CPU have never been this close!

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Folding Solar Panel Is Underpowered

March 15, 2024 by 29 Comments

If you hang out on certain kinds of sites, you can find huge-capacity USB drives and high-power yet tiny solar panels, all at shockingly low prices. Of course, the USB drives just think they are huge, and the solar panels don’t deliver the kind of power they claim. That seems to be the case with [Big Clive’s] latest folding solar panel purchase. The nice thing about the Internet is you can satisfy your urge to tear things open to see what’s inside of them vicariously instead of having to buy a lot of junk yourself. Thanks [Clive]!

The picture on the website didn’t match the actual product, which was the first sign, of course. The panel’s output in full sun was around 2.5 watts instead of the claimed 10 watts. He’s also seen sellers claim they are between 20 and 80-watt panels. But the interesting bits are when [Clive] decides to rip the panel into pieces and analyze the controller board.

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Stacking Solar Cells Is A Neat Trick To Maximise Efficiency

March 7, 2024 by 51 Comments

Solar power is already cheap and effective, and it’s taking on a larger role in supplying energy needs all over the world. The thing about humanity, though, is that we always want more! Too much, you say? It’s never enough!

The problem is that the sun only outputs so much energy per unit of area on Earth, and solar cells can only be so efficient thanks to some fundamental physical limits. However, there’s a way to get around that—with the magic of tandem solar cells!

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