Solar System Wars: Walmart Versus Tesla

It seems like hardly a day goes by that doesn’t see some news story splashed across our feeds that has something to do with Elon Musk and one or another of his myriad companies. The news is often spectacular and the coverage deservedly laudatory, as when Space X nails another double landing of its boosters after a successful trip to space. But all too often, it’s Elon’s baby Tesla that makes headlines, and usually of the kind that gives media relations people ulcers.

The PR team on the automotive side of Tesla can take a bit of a breather now, though. This time it’s Elon’s solar power venture, Tesla Energy Operations, that’s taking the heat. Literally — they’ve been sued by Walmart for rooftop solar installations that have burst into flames atop several of the retail giant’s stores. While thankfully no lives have been lost and no major injuries were reported, Walmart is understandably miffed at the turn of events, leading to the litigation.

Walmart isn’t alone in their exposure to potential Tesla solar problems, so it’s worth a look to see what exactly happened with these installations, why they failed, and what we as hackers can learn from the situation. As we’ll see, it all boils down to taking electrical work very seriously and adhering to standards designed to keep everyone safe, even when they just seem like a nuisance.

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Is Solar Right For You? Find Out!

Solar panels are revolutionizing the electric power industry, but not everyone is a good candidate for rooftop solar. Obviously people in extreme northern or sothern latitudes aren’t going to be making a ton of energy during the winter compared to people living closer to the equator, for example, but there are other factors at play that are more specific to each individual house. To find out if any one in particular will benefit from solar panels, [Jake] and [Ryan]’s solar intensity sensor will help you find out.

The long-term intensity tracker is equipped with a small solar panel and a data recording device, properly contained in a waterproof enclosure, and is intended to be placed in the exact location that a potential solar installation will be. Once it has finished gathering data, it will help determine if it makes economical sense to install panels given that the roof slope might not be ideal, landscaping may be in the way, or you live in a climate where it rains a lot in the summer during peak production times.

As we move into the future of cheap, reliable solar panels, projects like this will become more and more valuable. If you’re not convinced yet that photovoltaics are the way of the future, though, there are other ways of harnessing that free solar power.

Solar-Harvesting Blinkenlights

A few years ago a fad ripped through the makersphere where people would build cheap, solar powered LED blinkers, glue a magnet to them, and throw them on anything metal. It was an interesting time, but luckily did not last for too long. With some effort and craftsmanship, though, the solar throwie idea can be turned into something more elegant, though, such as this solar harvesting blinking gadget.

Like its predecessors, the device itself behaves simply, although this one is equipped with a small supercapacitor which can run the device for 8 hours without sun. It has a small solar panel which can charge the capacitor in five minutes, and from there the LEDs inside simply blink. The quality shows in the final packaging, as [Jasper] has taken to encasing them in epoxy shapes such as pyramids, for a nice paperweight or tchotchke. It is also noteworthy because of Jasper’s test device; since he is mass producing them he needed something to test each board for functionality before encasing them in the epoxy, and he built a small pen tester specifically for them too.

While the build is pretty straightforward, anyone looking to enclose a simple circuit in epoxy without bubbles or other problems might want to check this one out. It would also be a good platform for building other throwie-like projects on top of. In the past they didn’t just blink lights but also did things like run small Linux servers.

Stack Of Plant Saucers, Transformed Into Low Cost Solar Shield

For serious data collection with weather sensors, a solar shield is crucial. The shield protects temperature and humidity sensors from direct sunlight, as well as rain and other inclement weather, without interfering with their operation. [Mare] managed to create an economical and effective shield for under three euros in materials.

It began with a stack of plastic saucers intended for the bottom of plant pots. Each of these is a lot like a small plate, but with high sides that made them perfect for this application. [Mare] cut the bottom of each saucer out with a small CNC machine, but the cut isn’t critical and a hand tool could also be used.

Three threaded rods, nuts, and some plastic spacers between each saucer yields the assembly you see here. When mounted correctly, the sensors on the inside are protected from direct exposure to the elements while still allowing airflow. As a result, the readings are more accurate and stable, and the sensors last longer.

The top of the shield is the perfect place to mount a UV and ambient light sensor board, and [Mare] has a low-cost DIY solution for that too. The sensor board is covered by a clear glass dish on top that protects the board without interfering with readings, and an o-ring seals the gap.

3D printing is fantastic for creating useful components, and has been instrumental in past weather station builds, but projects like these show not everything needs to be (nor should be) 3D printed.

Soak Up The Sun With This 3D Printed Solar Harvester

At first glance, adding solar power to your project might seem easy. Get a photovoltaic panel, point it towards the big ball of burning gas in the sky, and off you go. But in reality, there’s a bit more to it than that. Especially when you’re trying to do something on a small scale. Without a rooftop full of panels pumping out power, you’ve got to take what you can get.

If you’re looking to power small electronic devices such as sensors with a single solar panel, [Vadim Panov] has put together a very concise write-up and video on building a low-cost solar harvester. It combines a relatively small photovoltaic panel, a charging circuit, and a battery for energy storage into a easily mountable package. He’s provided all the details necessary to create your own version, all you have to do now is come up with the application for it.

As far as the electronics go, this project is about as straightforward as it gets. The three watt panel is connected up to a simplistic charging circuit, which in turn feeds into a single 18650 cell. You might be wondering why a charge controller is even necessary in such a simple set up. One problem is that the output voltage of the panel is higher than that of the battery. You also need a blocking diode that will prevent the battery from discharging into the cell during the night or in cloudy conditions.

While the electronics might seem elementary to some readers, we think the 3D printed case alone is worth taking a look at. Not only has [Vadim] come up with a design that perfectly encloses the fragile solar panel and associated electronics, but in the video after the break, he also explains how the entire thing can be made waterproof with an epoxy coating. As 3D prints can have a tendency to be porous, this technique is definitely something you should file away mentally if you’ve been thinking of deploying a printed enclosure outdoors.

Whether you’re looking to power environmental sensors for as near a century as is technically possible or a portable OpenWRT router for mobile anonymity, these small solar panels hold a lot of promise if you know how to work around their limitations.

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Give Your Solar Garden Lights A Color Changing LED Upgrade

White LEDs were the technological breakthrough that changed the world of lighting, now they are everywhere. There’s no better sign of their cost-effective ubiquity than the dollar store solar garden light: a complete unit integrating a white LED with its solar cell and battery storage. Not content with boring white lights on the ground, [Emily] decided to switch up their colors with a mix of single-color LEDs and dynamic color-changing LEDs, then hung them up high as colorful solar ornaments.

The heart of these solar devices is a YX8018 chip (or one of its competitors.) While the sun is shining, solar power is directed to charge up the battery. Once the solar cell stops producing power, presumably because the sun has gone down, the chip starts acting as a boost converter (“Joule thief”) pushing a single cell battery voltage up high enough to drive its white LED. Changing that LED over to a single color LED is pretty straightforward, but a color changing LED adds a bit of challenge. The boost converter deliver power in pulses that are too fast for human eyes to pick up but the time between power pulses is long enough to cause a color-changing circuit to reset itself and never get beyond its boot-up color.

The hack to keep a color-changing LED’s cycle going is to add a capacitor to retain some charge between pulses, and a diode to prevent that charge from draining back into the rest of the circuit. A ping-pong ball serves as light diffuser, and the whole thing is hung up using a 3D-printed sheath which adds its own splash of color.

Solar garden lights are great basis for a cheap and easy introduction to electronics hacking. We’ve seen them turn into LED throwies, into a usable flashlight, or even to power an ATTiny microcontroller.

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Solar Power Is Set To Get More Expensive

The sun constantly bathes half the planet with energy. The energy may be free, but the methods for converting it to electricity cost money. Last year, the Chinese government cut subsidies to their solar panel manufacturers to shrink the industry which was perceived as bloated. This forced Chinese solar panel makers to cut prices to clear inventory. This drove down prices about 30%, making solar power cheaper than ever.

Reuters is reporting that Eric Luo, president of one of the largest solar panel makers in China, predicts that “the party is definitely over.” Speaking at the World Economic Forum, Luo said that prices have quit dropping and he expected industry consolidation to cause prices to rise by as much as 15% over the next two years.

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