Stacking Solar Cells Is A Neat Trick To Maximise Efficiency

March 7, 2024 by Lewin Day 52 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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Making A Dye-Sensitized Solar Cell Is Almost DIY-able

February 28, 2024 by Lewin Day 9 Comments

We see plenty of solar projects here on Hackaday, but they primarily consist of projects that use an off-the-shelf solar panel to power something else. We see very few projects where people actually create their own solar panels. And yet, that’s precisely what [Shih Wei Chieh] has done!

The project consists of a large dye-sensitized solar panel. These are a type of solar panel that can easily be created by the DIY builder, though their efficiency leaves something to be desired versus the best commercial types available. However, you can build them in any way you like to suit your application, which can have some potential benefits.

It consists of two pieces of FTO glass that is etched and prepared to become the electrodes for a string of solar cells. The cells have to be treated with titanium dioxide and then laced with silver traces, before being assembled with liquid electrolyte squirted in between. It’s finicky stuff, but the video almost makes it look easy… if you’re familiar with working in a chemistry lab, that is.

While it’s DIY-able, it’s at the outer edge of what some of us would be comfortable with. It does involve some steps with semi-obscure chemicals and the use of a kiln to produce the cells. The design shown here outputs around 5.8 volts and 51 milliamps. It’s not heaps, but it’s enough to run a low-power project for some time in an area with decent sun.

We’ve seen some other great solar projects over the years, too! Video after the break.

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A Smarter Solar Water Heater

February 25, 2024 by Bryan Cockfield 81 Comments

Installing solar power at a home is a great way to reduce electricity bills, especially as the cost of solar panels and their associated electronics continue to plummet. Not every utility allows selling solar back to the grid, though, so if you’re like [Rogan] who lives in South Africa you’ll need to come up with some clever tricks to use the solar energy each day while it’s available to keep from wasting any. He’s devised this system for his water heater that takes care of some of this excess incoming energy.

A normal water heater, at least one based on electric resistive heaters, attempts to maintain a small range of temperatures within the insulated tank. If the temperature drops due to use or loss to the environment, the heaters turn on to bring the temperature back up. This automation system does essentially the same thing, but allows a much wider range of temperatures depending on the time of day. Essentially, it allows the water heater to get much hotter during times when solar energy is available, and lets it drop to lower values before running the heater on utility electricity during times when it isn’t. Using a combination ESP32 and ATtiny to both control the heater and report its temperature, all that’s left is to program Home Assistant to get the new system to interact with the solar system’s battery charge state and available incoming solar energy.

While it’s an elegantly simple system that also affords ample hot water for morning showers, large efficiency gains like this can be low-hanging fruit to even more home energy savings than solar alone provides on paper. Effectively the water heater becomes another type of battery in [Rogan]’s home, capable of storing energy at least for the day in the form of hot water. There are a few other ways of storing excess renewable energy as well, although they might require more resources than are typically available at home.

Solar E-Ink Weather Station Works On Dark Days, Too

February 22, 2024 by Kristina Panos 11 Comments

One way to get through the winter doldrums is to take notice of the minuscule positive changes in weather as spring approaches. Although much of the US is experiencing a particularly warm month, that’s not the case in Germany where [rsappiawf] resides. Even so, they are having a good time charting the weather on their new solar-powered E-ink weather station.

And in spite of the dark winter days, the device has been delivering weather updates for over a week on solar power alone. The brains of this operation is an ESP32 S3 Mini, which [rsappiawf] operated on a little bit. For starters, they removed the integrated RGB LED in order to save precious milliamps. Then they upgraded the voltage regulator to a TPS73733DCQR.

[rsappiawf] also has a TPL5110 power timer breakout module in the mix, which saves even more power by only turning on every once in a while according to the potentiometer setting, and only then turning on the project’s power. Check out the brief demo after the break, including the cool sliding action into the 3D-printed holder.

There’s a lot you can do to lower power consumption in a project like this. Here’s one that will go 60 days on a charge.

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Open-Source Solar Modules

February 5, 2024 by Bryan Cockfield 13 Comments

As the price of solar panels continues to fall, more and more places find it economical to build solar farms that might not have been able to at higher prices. High latitude locations, places with more clouds than sun, and other challenging build sites all are seeing increased green energy development. The modules being used have one main downside, though, which is that they’re essentially a black box encased in resin and plastic, so if one of the small cells fails a large percentage of the panel may be rendered useless with no way to repair it. A solar development kit like this one from a group called Biosphere Solar is looking to create repairable, DIY modules that are completely open source, to help solve this issue.

The modular solar panel is made from a 3D printed holster which can hold a number of individual solar cells. With the cells placed in the layout and soldered together, they are then sandwiched between a few layers of a clear material like acrylic or glass with a seal around the exterior to prevent water intrusion. Since the project is open-source any number of materials can be used for the solar cell casing, and with the STL file available it’s not strictly necessary to 3D print the case as other manufacturing methods could be used. The only thing left is to hook up a DC/DC converter if you need one, and perhaps also a number of bypass and/or blocking diodes depending on your panel’s electrical layout.

The project is still in active development, and some more information can be found at the project’s website. While the “recyclability” of large-scale solar farms is indeed a problem, it’s arguably one which has been overblown by various interests who are trying to cast doubt on green energy. A small build like this won’t solve either problem anytime soon, so the real utility here would be for home users with small off-grid needs who want an open-source, repairable panel. It’s a great method to make sure solar technology is accessible and repairable for anyone that wants it, and in a way this approach to building hardware reminds us a lot of the Framework laptops.

Garden Light Turned Mesh Network Node

January 21, 2024 by Danie Conradie 11 Comments

We love a good deal, especially when it comes to scavenging parts for projects. Cheap outdoor solar lights are more than just garden accessories; they’re a handy source of waterproof enclosures, solar panels and batteries. This is demonstrated by [Tavis], who turned one such light into a Meshtastic LoRa communication node.

Solar Light With Meshtastic node inside — Where there’s an antenna, there’s a radio

A nice feature on this specific $15 Harbor Breeze Solar LED is the roomy solar panel enclosure with integrated 18650 battery holder, allowing for easy battery swaps. [Tavis] was able to easily fit the RAKwireless modular dev board, and wire it into the light’s charging circuit. The cheap circuit is likely not the most efficient, but will probably get the job done. It’s always possible to just swap it out with a better charging board. [Tavis] also added an external antenna by using a panel-mount SMA pigtail connector.

The Meshtastic project is all about enabling text-only communications through LoRa-based mesh networks, built using off-the-shelf devices and development boards that won’t break the bank. The project has seen some incredible growth, with people all over the world setting up their own networks.

It’s not the first time we’ve seen garden lights get used in project. We’ve seen MQTT added to a PIR solar light with some clever power saving circuitry, and as a power source for Attiny85-based projects.

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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