DIYers and enthusiasts should still worry about their house burning down because one of these boards started a fire. An insurance company would investigate and find any excuse they can to deny payment.
That's basically what most software Open Sorce projects state in their licenses as well: Use at your own risk. As someone who publishes design files openly you really don't want to be liable if someone uses the hardware in a wrong way.
That being said, the Libre Solar components are also meant to be used as the basis for customization (hence, called building blocks). Some of the devices are used with minor modifications in certified commercial products.
Apart from boats/caravans, DC systems are used a lot for rural electrification in the global south. This is also where the communication features of Zephyr RTOS are very important.
Not that this is accepted by insurers or AHJs ("authorities having jurisdiction"), but one can use UL-certified components in an (open-source) _assembly_ that itself isn't UL certified. This at least supports the argument that the overall product is safe if thoughtfully designed and assembled. An example is the OpenEVSE level-2 car charger (which I had a really good experience with).
If you're not selling them then there isn't really any certification requirements until you start to get into the mains voltages. This all seems to be 12/24V DC stuff on the battery side and 60V DC on the solar side which comes under 'extra-low voltage' in basically every jurisdiction which is usually not really regulated because it's difficult to shock someone.
The battery stuff is more risky (bringing lithium cells into the picture) but I don't think anyone should be worried by the MPPTs.
There's nothing stopping a company from creating products based on these, and having them certified, assuming they satisfy the requirements for certification (which if they don't you probably don't want to put it in your house anyway). I'm not familiar with the cern hardware license, but it appears to allow commercialization.
One component I haven't seen discussed here is that you also likely can't use them for anything but entirely off-grid setups. I've heard that in our locality, and I think this is pretty common around the US, that they won't permit you, and the utility won't allow grid tie of anything at all sketchy, including UL listed panels you buy used.
This is a very nice development, but it is tackling the easy stuff. I'd love to see an open source inverter that can operate in stand-alone mode or in grid connected mode. All of these grid connected devices with closed source are a massive risk, especially given how small and cheap a WiFi or cell modem is nowadays.
Glad to hear it - but cost of renewable energy isn't the software or hardware locked behind vendors. Its installers, wholesalers and permitting. Pricing is set to about where homeowners will be willing to pay and installers will make a good profit. If only it was a 5 year payback - we'd see it everywhere in NA.
In the US the cost of the red tape / bureaucracy is about 3-4x the cost of the total installation in places like Australia on a per kw basis. Including the Ozzy red tape. The US just has very inefficient bureaucracy.
In Australia you can go from the notion of "hmm I might want to put some solar on my roof" to having it, approved, installed and running in a couple of weeks. Safely and legally. In the US you lose months at best. Half a year is nothing. And everybody involved wants to make a profit so that's where all the cost goes. The crazy thing is that even with all that cost and bloat it's still worth doing. Imagine how good it would be if the US could figure out how to do stuff efficiently.
Both cost and complexity have to come down there. A lot of the friction in the system is a combination of the fossil fuel industry lobbying very successfully against anything to do with renewables, local energy monopolists resisting change and the notion of competition from their own customers (or any form of competition), and inept politicians coming up with ways to keep those happy.
And as an EU person, it's not that much better here. Better than the US. But we can do better.
A meta comment and really don't want to distract from the product but as a Spanish speaker, the word "libre" for open source projects really grids my gears. It's specially bad when used with "libre" before the subject (like LibreOffice or Libre Solar). It sounds a bit like Brad Pitt saying "bonjourno" in Inglourious Basterds.
Libre does mean free as in freedom, but it also means available and released from prison.
It's from French, not from Spanish, and besides, everybody knows what the intentions are here so I don't think you need to feel offended in any way, that's your choice.
Great use case for solar shed/offgrid/cabin... I think people underestimate how much you can do with a solar shed , batteries, and the sorta reduced risk aspect of a shed catching fire vs a house. That being said its really easy to follow safety precautions. I cant wait to try this out.
- dc motor conversions for air conditioners and voltage controllers that can adapt to multiple panel types to drive it. There's a lot to be gained without going all-in an inverter. What if I stayed on grid but heavily offset my heating / cooling bill by having a wall mount unit that was free to run during daylight hours on a completely separate circuit?
- conversion kit to make the wall mount unit a heater in the winter months
- a DC home system for select appliances such as lights, computers, or even refrigerators. This requires more precise voltage regulators because DC is more finicky when you add / remove loads. But you save some losses in efficiency.
- a thermal battery, so my window mount cooler can freeze a solid block of ice all day during the sun, and use it to cool me when I get home. It would be sealed of course. But condensation would still have to be managed. Maybe a hot water tank adapter that uses excess electricity and dumps it in the tank, but not so much to explode. Again, a form of offset, not a replacement for gas. Another thermal battery could be a sewage tank that aborbs heat from the AC unit before it goes down the drain. This would reduce the load of the fan.
- a wind generator that works best in storms. It could dump straight to a heating element and fan indoors. Who wouldn't love free heat during violent storms? Maybe it could have a clutch (mechanical or electric) to tune the load to the wind gusts.
- a solar cooker, maybe with a molten fluid or superheated steam. The latter can go well above 500F so plenty hot enough for cooking. But of course very dangerous so would need a professional device, if it's even possible. But this would allow e.g. restaurants in the summer to offset or replace heating for their kitchens. It pains me to think of how much energy is wasted in a hot desert city to pay for a gas grill and then pay again to pump to he excess heat outside.
22 comments
[ 3.2 ms ] story [ 56.9 ms ] threadZephyrOS: https://github.com/zephyrproject-rtos/zephyr
Would there be value in modeling this system with TLA+?
Why build another open product?
There are a few GitHub topics for solar electricity:
solar: https://github.com/topics/solar
photovoltaic: https://github.com/topics/photovoltaic
pv: https://github.com/topics/pv
battery-management: https://github.com/topics/battery-management
ups-management: https://github.com/topics/ups-management
inverter: https://github.com/topics/inverter
Photovoltaic system: https://en.wikipedia.org/wiki/Photovoltaic_system
They say right here: https://libre.solar/software/
This somewhat limits the usefulness of the hardware anywhere you need to be insured, e.g. your house, boat or van.
(Also, Amazon is where most people get their solar equipment these days and you would be amazed how much of it is not UL certified either.)
That being said, the Libre Solar components are also meant to be used as the basis for customization (hence, called building blocks). Some of the devices are used with minor modifications in certified commercial products.
Apart from boats/caravans, DC systems are used a lot for rural electrification in the global south. This is also where the communication features of Zephyr RTOS are very important.
Same goes for all the random Chinese inverters people are buying and installing in their Homes, Boats and Vans. Doesn't seem to stop them.
The battery stuff is more risky (bringing lithium cells into the picture) but I don't think anyone should be worried by the MPPTs.
In Australia you can go from the notion of "hmm I might want to put some solar on my roof" to having it, approved, installed and running in a couple of weeks. Safely and legally. In the US you lose months at best. Half a year is nothing. And everybody involved wants to make a profit so that's where all the cost goes. The crazy thing is that even with all that cost and bloat it's still worth doing. Imagine how good it would be if the US could figure out how to do stuff efficiently.
Both cost and complexity have to come down there. A lot of the friction in the system is a combination of the fossil fuel industry lobbying very successfully against anything to do with renewables, local energy monopolists resisting change and the notion of competition from their own customers (or any form of competition), and inept politicians coming up with ways to keep those happy.
And as an EU person, it's not that much better here. Better than the US. But we can do better.
https://fosdem.org/2026/schedule/event/7Q9HMF-open-solar-pow...
2025 for archive:
https://archive.fosdem.org/2025/schedule/event/fosdem-2025-6...
Libre does mean free as in freedom, but it also means available and released from prison.
If anything it makes it more apt.
- dc motor conversions for air conditioners and voltage controllers that can adapt to multiple panel types to drive it. There's a lot to be gained without going all-in an inverter. What if I stayed on grid but heavily offset my heating / cooling bill by having a wall mount unit that was free to run during daylight hours on a completely separate circuit?
- conversion kit to make the wall mount unit a heater in the winter months
- a DC home system for select appliances such as lights, computers, or even refrigerators. This requires more precise voltage regulators because DC is more finicky when you add / remove loads. But you save some losses in efficiency.
- a thermal battery, so my window mount cooler can freeze a solid block of ice all day during the sun, and use it to cool me when I get home. It would be sealed of course. But condensation would still have to be managed. Maybe a hot water tank adapter that uses excess electricity and dumps it in the tank, but not so much to explode. Again, a form of offset, not a replacement for gas. Another thermal battery could be a sewage tank that aborbs heat from the AC unit before it goes down the drain. This would reduce the load of the fan.
- a wind generator that works best in storms. It could dump straight to a heating element and fan indoors. Who wouldn't love free heat during violent storms? Maybe it could have a clutch (mechanical or electric) to tune the load to the wind gusts.
- a solar cooker, maybe with a molten fluid or superheated steam. The latter can go well above 500F so plenty hot enough for cooking. But of course very dangerous so would need a professional device, if it's even possible. But this would allow e.g. restaurants in the summer to offset or replace heating for their kitchens. It pains me to think of how much energy is wasted in a hot desert city to pay for a gas grill and then pay again to pump to he excess heat outside.