solar

308 Articles

PTPM Energy Scavenger Aims For Maintenance-Free Sensor Nodes

August 1, 2018 by 13 Comments

[Mile]’s PTPM Energy Scavenger takes the scavenging idea seriously and is designed to gather not only solar power but also energy from temperature differentials, vibrations, and magnetic induction. The idea is to make wireless sensor nodes that can be self-powered and require minimal maintenance. There’s more to the idea than simply doing away with batteries; if the devices are rugged and don’t need maintenance, they can be installed in locations that would otherwise be impractical or awkward. [Mile] says that goal is to reduce the most costly part of any supply chain: human labor.

The prototype is working well with solar energy and supercapacitors for energy storage, but [Mile] sees potential in harvesting other sources, such as piezoelectric energy by mounting the units to active machinery. With a selectable output voltage, optional battery for longer-term storage, and a reference design complete with enclosure, the PPTM Energy Scavenger aims to provide a robust power solution for wireless sensor platforms.

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High Efficiency, Open-Sourced MPPT Solar Charger

July 31, 2018 by 28 Comments

A few years ago, [Lukas Fässler] needed a solar charge controller and made his own, which he has been improving ever since. The design is now mature, and the High Efficiency MPPT Solar Charger is full of features like data logging, boasts a 97% efficiency over a range of 1 to 75 Watts, and can be used as a standalone unit or incorporated as a module into other systems. One thing that became clear to [Lukas] during the process was that a highly efficient, feature-rich, open-sourced hardware solution for charge controllers just didn’t exist, at least not with the features he had in mind.

Data logging and high efficiency are important for a charge controller, because batteries vary in their characteristics as they recharge and the power generated from things like solar panels varies under different conditions and loads. An MPPT (Maximum Point Power Tracking) charger is a smart unit optimized to handle all these changing conditions for maximum efficiency. We went into some detail on MPPT in the past, and after three years in development creating a modular and configurable design, [Lukas] hopes no one will have to re-invent the wheel when it comes to charge controllers.

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DIY solar panel vs. commercial solar panel

DIY Vs. Commercially Made Solar Panel

July 23, 2018 by 31 Comments

The price of commercially made solar panels on eBay is around $1 per watt and have been for a few years, but the price of individual solar cells are likewise at a low price per watt, around $0.48.  Looking at those prices, it’s tempting to say that it’d be cheaper to just buy the solar cells and put together your own panels. But is it? Simply adding up all the costs might seem like a good way to tell, but you’d need to make a panel to really see what works and what doesn’t.

Part US$ Euros €
solar cells 53 45
aluminum U-channel 20 17
plexiglass 43 37
adhesive 8 7
clear epoxy resin 40 34
Total $164 140€

And so [GreatScott] did just that, with his own side-by-side comparison. He made a 100-watt solar panel and mounted it on his roof beside his commercially produced 100-watt one and compared their output.

The cost of his DIY panel rose quickly. To make a somewhat comparable panel he needed to buy aluminum U-channels, clear epoxy resin, and more. Shown here is the breakdown of his costs.

His commercial 100 watt solar panel would cost him $103 today (87.90€). Compare that to his $164 DIY panel. Also, his DIY one likely won’t weather as well as the commercial one and may not handle high temperatures as well either. You can see the results of his testing in the video below, along with all his construction steps.

Another component open to DIYers in a solar system is the charge controller which takes the solar panel’s output and uses it to charge the battery, with added features like MPPT. Check out this DIY charge controller with MPPT and WiFi for data logging.

Continue reading “DIY Vs. Commercially Made Solar Panel” →

SPINES Design Makes For Modular Energy Harvesting

July 17, 2018 by 7 Comments

The SPINES (Self-Powered IoT Node for Environmental Sensing) Mote is a wireless IoT environmental sensor, but don’t let the neatly packed single PCB fool you into thinking it’s not hackable. [Macro Yau] specifically designed SPINES to be highly modular in order to make designing an energy harvesting sensor node an easier task. The way [Macro] sees it, there are two big hurdles to development: one is the energy harvesting itself, and the other is the software required to manage the use of every precious joule of that harvested energy.

[Macro] designed the single board SPINES Mote in a way that the energy harvesting portion can be used independently, and easily integrated into other designs. In addition, an Arduino library is being developed to make it easy for the power management to be done behind the scenes, allowing a developer to concentrate on the application itself. A solar-powered wireless sensor node is one thing, but helping people get their ideas up and running faster in the process is wonderful to see.

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Row Your Bike To China

July 16, 2018 by 11 Comments

If you’re a fan of endurance racing motor vehicles, there’s one that puts the 24 Hours of Le Mans, the Dakar Rally, and the Baja 1000 to shame, and the race doesn’t even involve cars. Indeed, the vehicles used for this massive trek from France to China are electric bicycles, powered only by solar panels. This is the epic Sun Trip endurance race, and one of its competitors built a unique tandem bike that is powered both by pedaling, rowing, and the solar panels.

The tandem bike is interesting on its own since the atypical design uses a back-to-back layout which means one person is facing backward, but the storage space is dramatically increased over the normal forward-facing layout. The person in the rear doesn’t pedal, though. [Justin_le] built an upper-body-powered rowing station for that spot so that the person riding back there can rest their legs but still help propel the vehicle. Of course, there’s also a solar panel roof so the two riders can pedal and row in the shade, which includes MPPT and solar tracking which drives a small electric motor on board as well.

This race started in June but is still going on. There’s a live GPS feed so you can keep up with the teams, and if you get really inspired you can go ahead and sign up for the 2019 race as well. This particular bike was also featured on Radio Canada as well if you’d like to learn more about it.

Thanks to [Arthur] for the tip!

IoT Solar Pool Heating

July 14, 2018 by 10 Comments

A backyard swimming pool can be a great place to take a refreshing dip on a summer’s day. It can also be a place to freeze your giblets off if the sun has been hiding for even a few hours. That can make pools an iffy proposition unless they’re heated, and that starts to get really expensive in terms of upfront costs and ongoing charges for fuel or power. Unless you put the sun and the IoT to work for pool-heating needs.

Preferences vary, of course, but [Martin Harizanov] and his family clearly like their swims on the warm side. With nobody using the pool when it was below 25°C (77°F), [Martin] picked up a few bits to harness the sun to warm the water. Loops of PVC lawn irrigation tubing were tossed onto a shed roof with a favorable solar aspect and connected to the pool with a length of garden hose. The black thin-wall tubing is perfect for capturing the sun’s energy, and 200 meters of the stuff can really heat things up fast. A small pump is controlled by a microcontroller — it’s not explicitly stated but we suspect it’s a Raspberry Pi — with a pair of temperature sensors to sample the water in the pool and in the heating loop. Metrics are gathered and logged by Emoncms, an open source energy monitoring app. [Martin] says he’s harvesting about 10 kW from the sun on a good day, and that the pool water in the heating loop has gotten up to a steamy 55°C (131°F) without any other energy inputs other than the pump.

Plenty of others have made the leap to solar for pool season extension, with designs from the simple to the more complex. And if you live where the sun doesn’t shine, there’s always a compost water heater.

Ultra-Low Power, Energy Harvesting Battery Charger

July 8, 2018 by 10 Comments

This half-inch square ultra-low power energy harvesting LiPo cell charger by [Kris Winer] uses a low voltage solar panel to top up a small lithium-polymer cell, which together can be used as the sole power source for projects. It’s handy enough that [Kris] uses them for his own projects and offers them for sale to fellow hackers. It’s also his entry into the Power Harvesting Challenge of the Hackaday Prize.

The board is essentially a breakout board for the Texas Instrument BQ25504, configured to charge and maintain a single lithium-polymer cell. The BQ25504 is an integrated part that takes care of most of the heavy lifting and has nifty features like battery health monitoring and undervoltage protection. [Kris] has been using the board along with a small 2.2 Volt solar panel and a 150 mAh LiPo cell to power another project of his: the SensorTile environmental data logger.

It’s a practical and useful way to test things; he says that an average of 6 hours of direct sunlight daily is just enough to keep the 1.8 mA SensorTile running indefinitely. These are small amounts of power, to be sure, but it’s free and self-sustaining which is just what a remote sensing unit needs.

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