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

January 17, 2024 by Dan Maloney 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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How To Build A Small Solar Power System

December 30, 2023 by Jenny List 41 Comments

We live in an exciting time with respect to electrical power, one in which it has never been easier to break free from mains electricity, and low-frequency AC power in general. A confluence of lower-power appliances and devices using low-voltage external switch-mode supplies, readily available solar panels and electronic modules, and inexpensive high-capacity batteries, means that being your own power provider can be as simple as making an online order.

But which parts should you choose? Low Tech Magazine has the answer, in the form of a guide to building a small solar power system. The result is an extremely comprehensive guide, and though it’s written for a general audience there’s still plenty of information for the Hackaday reader.

Perhaps the most important part is that it’s demystifying the subject, there in front of us are a set of pretty straightforward recipes for personal power. The computer this is being written on spends a significant proportion of its time on the road with the ever-present company of a very hefty USB-C power pack for example, and the realization that a not-too-expensive solar panel and USB PD source could lessen the range anxiety and constant search for a train seat with a socket for a writer on the move is quite a powerful one.

Take a look and see whether your life could use bit of inexpensive off-grid power, meanwhile we’re quite pleased that the USB-C PD standard has eased some of the DC problems we expressed frustration at back in 2016.

Re-imagining The Water Supply

October 15, 2023 by Bryan Cockfield 49 Comments

Getting freshwater supplied across cities and towns in a reliable and safe way is no simple task. Not only is a natural freshwater reservoir or other supply needed, but making sure the water is safe to drink and then shipping it out over a dense network of pumps and pipes can cost a surprising amount of time and money. It also hinges on a reliable power grid, which is something Texas resident [Suburban Biology] doesn’t have. But since fresh water literally falls out of the sky for free, he decided to take this matter into his own hands.

The main strategy with a system like this is to keep the rainwater as clean as possible before storage so that expensive treatment systems are less necessary. That means no asphalt shingles, a way to divert the first bit of rain that washes dust and other contaminants off the roof away, and a safe tank. This install uses a 30,000 gallon tank placed above ground for storage, but that’s not the only thing that goes into a big rainwater catchment system like this. A system of PVC pipes are needed both for sending rainwater from the roofs of the buildings into the tank and for pumping it into the home for use. With all of that in place it’s both a hedge against climate change, unstable electric grids, and even separates the user from the local aquifer which may or may not have its own major issues depending on where you live.

While Texas legally protects the rights of citizens to collect and store rainwater, the same isn’t true for all areas. For example, Colorado only just passed a law allowing the collection and storage of a meager 110 gallons of rainwater and forbade it entirely beforehand. There are some other considerations for a project like this too, largely that above-ground systems generally won’t work in cold climates. On the other hand, large systems like these are really only needed where rainfall is infrequent; in more tropical areas like south Florida a much smaller storage system can be used

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A series of trapezoidal steel "buckets" attached together to form a metal water wheel. They are arranged around a square center frame that attaches to a hub for the wheel to spin about. The wheel is next to a stream and four people of various ages appear to be talking around it. A cinder block building with a metal roof is in the left background, and an older, yellow stone building is far off in the distance on the right of the image. The landscape is lush, green, and mountainous.

Open Source Waterwheel

August 20, 2023 by Navarre Bartz 28 Comments

Here in the West, power going out is an unusual event. But in more remote regions like the Himalayas, reliable electricity isn’t a given. A group of local craftspeople, researchers, and operators in Nepal have worked together to devise a modular waterwheel system.

Based on a 20-30 cm-wide bucket module consisting of only four galvanized steel components, the wheels can be easily built and deployed using resources and tools that are easy to find anywhere in the world. Current test devices generate between 120 and 1,400 Watts of power, depending on the device’s size.

A software tool was also developed that takes the head and flow rate of a location as inputs to calculate the dimensions of the optimal wheel and expected power output for an installation. This lets communities find ideal sites for power generation and calculate the expected costs.

We’ve covered a few other DIY hydropower setups, from repurposed washing machines to custom scratch builds.

Converting On-Grid Electronics To Off-Grid

May 11, 2023 by Dave Rowntree 54 Comments

Husband and wife team [Jason & Kara] hail from Canada, and in 2018, after building their own camper, sold up their remaining earthly goods and headed south. If you’re not aware of them, they documented their journey on their YouTube channel, showing many interesting skills and hacks along the way. The video we’re highlighting today shows a myriad of ways to power all the DC-consuming gadgets this they lug along with them.

LiFePO4 batteries are far superior to lead acid for mobile solar installations.

Their heavily modded F-550 truck houses 12kWh of LiFePO4 batteries and a 1.5kW retractable solar array, with a hefty inverter generating the needed AC power. They weren’t too happy with the conversion losses from piles of wall warts that all drained a little power, knowing that the inverter that fed them was also not 100% efficient. For example, a typical laptop power brick gets really hot in a short time, and that heat is waste. They decided to run as much as possible direct from the battery bank, through different DC-DC converter modules in an attempt to streamline the losses a little. Obviously, these are also not 100%

efficient, but keeping the load off the inverter (and thus reducing dependency upon it, in the event of another failure) should help stem the losses a little. After all as [Jason] says, Watts saved are Watts earned, and all the little lossy loads add up to a considerable parasitic drain.

One illustration of this is their Starlink satellite internet system consumes about 60W when running from the inverter, but only 28W when running direct from DC. Over the course of 24 hours, that’s not far off 1kWh of savings, and if the sun isn’t shining, then that 12kWh battery isn’t going to stretch as far.

There are far too many hacks, tips, and illustrations of neat space and power-saving solutions everywhere, to write here. Those interested in self-build campers or hacking a commercial unit may pick up a trick or two.

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Building A Communications Grid With LoRaType

March 13, 2023 by Bryan Cockfield 33 Comments

Almost all of modern society is built around various infrastructure, whether that’s for electricity, water and sewer, transportation, or even communication. These vast networks aren’t immune from failure though, and at least as far as communication goes, plenty will reach for a radio of some sort to communicate when Internet or phone services are lacking. It turns out that certain LoRa devices are excellent for local communication as well, and this system known as LoraType looks to create off-grid text-based communications networks wherever they might be needed.

The project is based around the ESP32 platform with an E22 LoRa module built-in to allow it to operate within its UHF bands. It also includes a USB-based battery charger for its small battery, an e-paper display module to display the text messages without consuming too much power, and a keyboard layout for quickly typing messages. The device firmware lets it be largely automated; it will seek out other devices on the local mesh network automatically and the user can immediately begin communicating with other devices on that network as soon as it connects.

There are a few other upsides of using a device like this. Since it doesn’t require any existing communications infrastructure to function, it can be used wherever there are no other easy options, such as in the wilderness, during civil unrest where the common infrastructure has been shut down, or simply for local groups which do not have access to cell networks or Internet. LoRa is a powerful tool for these use cases, and it’s even possible to network together larger base stations to extend the range of devices like these.

Off-Grid Van Build Uses 3D Scanning For Smarter Planning

January 22, 2023 by Donald Papp 44 Comments

Folks who refurbish and rebuild vans into off-grid campers (especially with the ability to work in them remotely) put a fantastic amount of planning and work into their projects. [Rob] meticulously documented his finished van conversion and while he does a ton of clever work, we especially liked how he shows modern tools like photogrammetry can improve the process.

Photogrammetry helped turn a bunch of photos from different angles into a textured 3D model with accurate dimensions.

[Rob] used a camera and photogrammetry software to 3D scan the van inside and out. The resulting model means that CAD tools can better assist with the layout and design phase. This is an immense help, because as [Rob] points out, an empty van is anything but a hollow box on wheels. Every surface is curved, none of the sides are identical, and there frankly isn’t a right angle to be found anywhere. When every little scrap of space counts, it’s important to have an accurate reference.

Of course, mapping the work are was just the beginning. It took six months, but he turned a Volkswagen Crafter cargo van into a slick off-grid camper capable of remote work. The full series of videos is on his site, but you can also watch the video highlights, embedded below.

The photogrammetry was done with Meshroom, and if you’d like to know more, we’ve previously explained different 3D scanning methods and how they can help with design work like this.

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