This somewhat limits the usefulness of the hardware anywhere you need to be insured, e.g. your house, boat or van.
ZephyrOS: 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
The battery stuff is more risky (bringing lithium cells into the picture) but I don't think anyone should be worried by the MPPTs.
(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.)
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.
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.
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.
They say right here: https://libre.solar/software/
I got solar installed by the local power company and while it's well done and was a great deal regarding the price, the inverter stats are locked behind a really terrible app. At least there isn't a subscription cost but I wouldn't be surprised if they add one someday.
Would gladly pay more for fully open and serviceable replacement.
Grid-connected is an entirely different ball game. You will not see any open source projects there, or at least not any that anyone will want to use.
Let's think about why not. Anything grid-connected, you REALLY want a licensed electrician to plan and install. And competent electricians will NOT go anywhere near a piece of equipment that is not UL certified. A company producing equipment is NOT going to go through the expense of getting UL certified and then just release their design, PCB, and schematics for free.
And I want to be clear that I am a strong proponent of open source hardware, there are just certain situations where the incentives in reality just don't line up. This is one of them.
The real reason this should give you pause is that you don't want your house to burn down regardless of an insurance payout. That is how your incentives remain aligned with the insurance company.
($3k would be for "unintentional radiator" device, i.e., not supposed to be a radio, $30k would be for "intentional radiator" device, i.e., supposed to be a radio)
A hobby BMS is usually a bad idea, as most kits from unknown origins prioritized cost over safety. Depending where you live, prior to roof installation there may be additional zoning and signed engineering drawing requirements.
It is not hard to find UL equipment, but expect to pay about another $600 for the BMS. Yet, it is better than a house burning down, and the insurance provider denying coverage.
Have a look at local certified installer companies, and make sure to get some real references in your town. Just like most HVAC companies... some installers are just over priced scams. Some folks claim https://www.pegasussolar.com/ was inexpensive, and might be worth a call. Best regards =3
Have you heard of balcony solar?
It's a solar panel, a microinverter, and a standard wall plug. It doesn't need an electrician to install any more than anything else, you just plug it in. Outlets work both ways.
LibreSolar doesn't seem to be working on any inverters, but a complete open source system like this would be great.
Competent electricians are licensed professionals who (1) stand to make money on selling gear and (2) have customers that hire them simply because they don't want the hassle or the liability. Obviously a licensed professional is not going to install your home brew inverter, but at the same time if you can design a homebrew inverter you probably don't need a licensed professional anyway.
I've rewired lots of homes and have never had an issue with any of this and designed my first inverter when I was 17 to power my room when my betters decided I should go to sleep and cut the power.
This stuff is not magic. If someone designs a modern open source inverter I'm definitely going to build and install it. Fortunately insurance companies here are reasonable: if your homebrew device wasn't the cause of the mishap then you are still insured.
The one thing they are very strict about is gas, because there is no such thing as a 'fuse for gas'. But if you've properly designed and fused your gear then it should be no less safe than any other grid connected device, even if the magic UL or TUV mark isn't there.
The big one is EMI, that can be hard to get right and you need some gear for this, which is why it pays off to pool the money for an open source design to be certified. And once certified of course the design is 'type approved' and frozen, so you can't change any of the hardware without going through recertification. This is expensive, but if you don't do it every other week should still be well within the means of a properly set up open source project.
Why the fearmongering? It's not as if we're 12 here.
Of course, there is a rising group of actually really high-quality native brands starting to come out of China - Anker were an early one of these, Xiaomi is a massive one, UGreen is really popular on Amazon etc. These kind of brands actually will be properly certified and are scary good for how cheap they are. So it's changing a lot.
Agreed - a lot of the inverters do some real BS moves around data management clearly a way to extract more value in a subscription mode. Its mind numbingly frustrating.
This project isn't being marketd to people who call up a company to white-glove the whole-home installation end-to-end. This is for DIYers who have enough knowledge to tinker with self-designed solar projects but not the EE degree required to engineer some of the more specialized equipment themselves.
I'll give a good example: I use solar to power a ham radio station for a weekend in the summer. However, nearly ALL of the equipment you can buy for the production and storage of solar power emits some degree of radio-frequency interference, which is bad when your whole goal is to power a very sensitive radio.
When it comes to charge controllers in particular, there are exactly two companies that claim to make RFI-quiet MPPT controllers. One has mixed reviews (some people say they work great, some say they are not any better than anything else), and one is very good but also very expensive for what you get. So, more open design and community feedback from people like me might get the cost of a reliable RFI-free charge controller down to where it should be.
- 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.
UL or other certification is a very good idea. They can't automatically deny coverage for lack of certification, but it becomes a much harder fight for you to prove the non-certified equipment wasn't at fault.
I would say that rules out about 80-95% of DYI users.
Also, it comes from French and Spanish [https://www.gnu.org/philosophy/free-sw.en.html], it's the same word and same grammar, subject before adjective.
Not a chance. Language is a tool, not some kind of holy house. If the meaning comes across that's already more than you could hope for.
The whole idea that language is something to be condensed and frozen is relatively new, it used to be much more fluid which made it harder to have a decisive set of words (sorry, Scrabblers (tm)) but language could adapt faster to circumstances. What we consider the 'final form' of all of these languages isn't final at all, it is just what we are used to and more of a convention than anything else.
Some countries (including mine, unfortunately) have groups that will go out of their way to harass people to use the 'correct form' ignoring that what those forms are is subject to change and that not everybody grew up with the currently agreed upon preferential way to spell things, and meaning is so much more complicated than spelling.
I think the easiest way to deal with these kind of frustrations is to see them as compliments: at least someone was aware enough of your language to name something in it, that's more than you could say for many other languages, if only because the scripts are different.
Also, there's no need for a transfer switch in any grid-tied system, whether plug-in or hard-wired. Grid-tied inverters shut off automatically if there's no grid frequency to sync to.