pv

9 Articles

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

January 17, 2024 by 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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ESP32 Makes Great MPPT Controller In Low-Cost Solar Installation

November 4, 2019 by 34 Comments

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.

Perovskites: Not Just For Solar Cells Anymore

June 13, 2019 by 21 Comments

If you’ve been around long enough, you’ll know there’s a long history of advances in materials science that get blown far out of proportion by both the technical and the popular media. Most of the recent ones seem to center on the chemistry of carbon, particularly graphene and nanotubes. Head back a little in time and superconductors were all the rage, and before that it was advanced ceramics, semiconductors, and synthetic diamonds. There’s always some new miracle material to be breathlessly and endlessly reported on by the media, with hopeful tales of how one or the other will be our salvation from <insert catastrophe du jour here>.

While there’s no denying that each of these materials has led to huge advancements in science, industry, and the quality of life for billions, the development cycle from lab to commercialization is generally a tad slower than the press would have one believe. And so when a new material starts to gain traction in the headlines, as perovskites have recently, we feel like it’s a good opportunity to take a close look, to try to smooth out the ups and downs of the hype curve and manage expectations.

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Solar Circuit Sculpture Pumms The Night Away

April 4, 2019 by 17 Comments

A word of warning: Google for the definition of the word “pummer” at your own risk. Rest assured that this beautiful solar-powered circuit sculpture fits the only definition of pummer that we care to deal with.

For the unfamiliar, a pummer is a device from the BEAM style of robotics, a sort of cyborg plant that absorbs solar energy during the day and turns it into a gently pulsating light that “pumms” away the dark hours.

[Mohit Bhoite]’s take on the pummer is an extraordinary model of a satellite executed mainly in brass rod. His attention to detail on the framework boggles our minds; we could work for days on a brass rod and never achieve the straight lines and perfect corners he did. The wings support two solar cells, while the hull of the satellite holds a dead-bugged 74HC240 octal buffer/line-driver chip and all the other pumm-enabling components. A one farad supercap – mounted to look like a dish antenna – is charged during the day and a single LED beacon blinks into the night.

No schematic is provided, but there are probably enough closeup shots to reverse engineer this, which actually sounds like a fun exercise. (Or you can cheat and fetch the PDF copy of the old Make magazine article that inspired him.)

Hats off to [Mohit] for a top-notch circuit sculpture. We’ve seen similarly detailed and well-executed sculptures from him before; something tells us this won’t be the last.

Thanks to [Varun Reddy] for the tip.

Self-Powered Sun Tracker Takes A Cue From NASA Solar Probe

November 18, 2018 by 32 Comments

Getting a solar array to track the sun has always been an interesting problem, and it has led to some complicated solutions. Controllers that use GPS and servos seem to be much in favor these days, but as this NASA-inspired sun tracker shows, the task needn’t be overly complex.

It’s pretty obvious from the video below that [NightHawkInLight]’s solar tracker is just a proof-of-concept for now, but it certainly shows promise. It’s based on NASA’s sun-skimming Parker Solar Probe, which uses sensors at the rear of the probe to maneuver the craft to keep sunlight from peeking around the sides of the shield. [NightHawkInLight]’s design simplifies that scheme even more, by using solar cells as the four sensors. The cells, mounted behind a solar shade, are directly connected to small gear motors that control azimuth and elevation. When a cell sees the sun, it powers the motor that moves the panel the right way to occlude the sun again, thereby cutting power to the motor.

[NightHawkInLight] mentions the obvious problem of what happens when the sun comes up and the array is pointing the complete opposite direction after the previous sunset, but we’re still not sure his solution – a larger array with tracking cells mounted further apart – will work. We’re also not sure how it will scale to larger arrays that need bigger motors to move. We’ve seen such arrays handled with more complicated trackers, of course, but we hope the simplicity of this design can be made practical for real-world use.

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Battery-Powered Watering Timer Converted To Solar On The Cheap

May 12, 2018 by 13 Comments

Watering the garden or the lawn is one of those springtime chores that is way more appealing early in the season than later. As the growing season grinds along, a chore that seemed life-giving and satisfying becomes, well, just another chore, and plants often suffer for it.

Automating the watering task can be as simple as buying a little electronic timer valve that turns on the flow at the appointed times. [A1ronzo] converted his water hose timer to solar power. Most such timers are very similar, with a solenoid-operated pilot valve in line with the water supply and an electronic timer of some sort. The whole thing is quite capable of running on a pair of AA batteries, but rather than wasting money on new batteries several times a season, he slipped a LiPo pack and a charge controller into the battery case slot and connected a small solar panel to the top of the controller.

The LiPo is a nominal 3.7-volt pack, so he did a little testing to make sure the timer would be OK with the higher voltage. The solar panel sits on top of the case, and the whole thing should last for years. And bonus points for never having to replace a timer that you put away at the end of the season with batteries still in it, only to have them leak. Ask us how we know.

Like the best of hacks, this one is quick, easy and cheap — $15 in parts, aside from the timer. There are more complicated irrigation solutions, of course, one of which even won the Hackaday Prize once upon a time. But this one has us ordering parts to build our own right now.

A Solar Freakin’ Walkway

October 13, 2017 by 22 Comments

Looking to add a little pizzazz to your back garden? Are those strings of lights hung in the trees looking a little dated? Why not try lighting your garden path with DIY solar-powered pavers?

If [jfarro]’s project looks like a miniature version of the much-touted solar freakin’ roadways concept, rest assured that there are huge differences. For one, these lighted pavers actually work — trust me on this; I live not far from the demo site for the Solar Roadways and the degree to which it underwhelms cannot be overstated. Granted, a garden path is a lot simpler to engineer than a road, but many of the challenges remain.

Using recycled glass blocks that are usually reserved for walls and windows, [jfarro] figured out how to attach Neopixel rings to the underside and waterproof them with a silicone conformal coating. The 12 lighted pavers he built draw considerable current, so a 45-watt solar array with charge controller and battery were installed to power the pavers. An Arduino and a motion sensor control the light show when someone approaches; more complicated programs are planned.

Hats off the [jfarro] for taking on a project like this. We don’t often see builds where electrical engineering meets civil engineering, and even on a small scale, dealing with dirt, stone, and water presents quite a few challenges. Here’s hoping his project lasts longer than the Solar Roadways project did.

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