Project status

[pixelpoppul-zz]

Is this project still continued or forgotten?

[transistorgrab]

Hi, it's not forgotten but dormant.

I have other things currently taking up my time. But if you're interested in helping I would gladly support and wake it up again and switch my priorities. :) It's a bit boring to do all the things alone…

[pixelpoppul-zz]

Would be great to continue given there arent much open source systems on the internet and the solar market is kinda booming :) mention when you left off and we can continue it

[transistorgrab]

Take a look at the latest Kicad files (just uploaded my latest modifications). I think I have a lot of the electronics in a good state. However, power electronics like AC inverter bridge and drivers are still open. This is the part where I have not the deepest knowledge and need to learn most. Which is why it's the last to be finished.

Software is totally open. I figured it's not much use to start anything software as long as it's not defined what hardware will be there and what needs to be considered in software.

Also look into the wiki section here. I documented as much as possible there. Read it over and see if it helps to understand what I wanted to create here. I'm open to feedback so don't hold back.

[pixelpoppul-zz]

Its not THAT complicated as three basic things Sensing Driving the hbridge Output control

I have rough schematics to do all three along with the hbridge ill look at the kicads once i get time like 20mins from now

U have basically almost figured out what to use and how to use it just needs to go in place :)

[pixelpoppul-zz]

do you have a email i could send you a sample file to? it has almost all of the things required(almost) all already kinda made

[transistorgrab]

you can send me your file to ansc dot de at gmail dot com

looking forward to it :)

[pixelpoppul-zz]

I think i missed the page we were on the file i sent was for a microinverter as this project looks like a string inverter. I think it will be easier on you to build a microinverter as its easy to code and design and is also cost efficient :)

[Thorbijoern]

i'm happy to see that there is some new developments here, after i didn't receive an answer on #5 i worried this is dead.

i think the types of inverters (string, micro, etc.) are a bit confusing. Judging from OSSI-2002 from Requirements Page it seems like a micro inverter ist the goal, but it should also have a very high input voltage like string inverters OSSI-2003. I don't know how one can accieve input ranges from ~18V for single solar panels and ~12V or ~24V for batteries, up to 600V. But i also don't know how one designs such boost stages and https://github.com/transistorgrab/OSSI/wiki/Electronics-and-Electrical#power-supply also talks about problems with the input range and efficiency.

https://libre.solar is also cool, they have some open MPPT charge controller designs and they make documentation on the design princibles, controlling and other things which might be helpful here too.

[pixelpoppul-zz]

There are solar panels tjat output 24v and custom ones do as much as 50!. Boost stages are nothing but just the transformer stepping the sine wave made by the full h bridge system. Bssic but works SPWM gives a higher return range and increases efficiency but it is hsrd to code on a microcontroller as the timings need to ne near perfect for a grid level pure sine wave inverter.

[transistorgrab]

@Thorbijoern Sorry for missing your message on #5. With the current situation it's a bit stressful to keep everything monitored.

There are different design goals here because I want to be able to realize different devices with as few as possible changes to the overall design. It's not aimed towards making the cheapest inverter on the planet but as a learning experience. I hope to make a as good as possible documentation about all design decisions for others to see what it takes to make a working inverter.

String inverters have multiple panels in series. Microinverters connect to one or two panels in parallel. I think it is possible to have a small solution that only takes one panel and charges a 12 V battery. But also a solution that takes a panel string and charges a higher voltage battery. Or it runs off a battery instead of a solar panel.

It's great that there are so many different projects now. :)

Just take a look at what is already there and ask questions or propose some measures or changes. I still have hopes that some day there will be a prototype. :D

[casainho]

Hi. I would be interest in having a Telegram channel so the development could be discussed. I am on 2 channels doing real development for EBike and EScooter motor controllers, all OpenSource projects, from design the hardware to the firmware and some software. And I am for DIY, easy to repair and build (as also reuse the knowledge and firmware): https://opensourceebike.github.io/ or https://github.com/EBiCS/EBiCS_motor_FOC

@transistorgrab would you like to created a Telegram channel for developers on this project?

Congratulations on this project, Solar and Battery seems will be a BIG thing in next years!!

[Saphira8105]

Hi all Is someone of you still working on this project? Would be interested to contribute. My background is in the area of communication technology like router and switch development. I saw the last poste more than a year ago. Would be great to contribute here to a platform which make it possible to have a cheep solution to build balcon pv systems for everyone. This can be a solution for the power issues we are facing possible this winter in Europe.

[transistorgrab]

Hi @Saphira8105, This project is dormant at the moment. Due to real life happening I did not find much time for it. However, if someone joins I would gladly revive it. Main problem at the moment is the power electronics stuff. I'm not an expert at this and this is a blocker for the actual important part of "inverter". Some side-projects showed me that one may think it's OK but when actually operating the thing it can show unexpected behaviour and break if you do not know exacly what you are doing.

[transistorgrab]

This project is still open for development. However, I'm stuck at the power electronics part, where the actual "inverter" function is affected. I'm no expert on this and had some experiments done that showed if you don't know what you're doing it will not work (reliably). So if you know someone who has some experience with power electronics, that could give the project new life.

[pixelpoppul-zz]

I'll surely take a look at it but can you brief what's not working reliably? Is the bridge not timed right or what is it?On Oct 5, 2022 9:37 PM, "André S." @.***> wrote: This project is still open for development. However, I'm stuck at the power electronics part, where the actual "inverter" function is affected. I'm no expert on this and had some experiments done that showed if you don't know what you're doing it will not work (reliably). So if you know someone who has some experience with power electronics, that could give the project new life.

—Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you authored the thread.Message ID: @.***>

[transistorgrab]

Currently there is still no actual hardware. The schematics shows the latest version. To summarize: on the DC input there still needs to be decided what is the right IGBT for the boost converter. There is only a generic part in the schematics. The inverter bridge is completely blank. There is input required what are the right components for the desired power class. For the Bridge drivers there is a first suggestion but the circuit is not designed. But this is just a minor issue.

Adding to that the component selection needs to be documented in a way that makes it clear without doubt why a certain component or ciruit was chosen to make it easier for later contributors if a change is required.

Additionally I will need to port the design to the latest version of Kicad to make it easier for interested persons to check the data. This will be the next step and should not take too long (hopefully ;) )

[pixelpoppul-zz]

We can decide what IGBT to use depends on power level we aim for and the inverter bridge itself should be not too difficult as spam circuits are widely available

[transistorgrab]

Well I think a first shot for power class could be the "balcony power plant" with 600 W output power. This would bring the general platform to life and most parts could be tested. At 600 W for 120 V this would put the current rating at 5 A for the worst case requirement. On the DC side with two 300 W panels in series the input current would be at about 10 Amps max. with current modules. But there are already 660 W modules that deliver up to 19 A… wow!

[pixelpoppul-zz]

What's the plan for MPPT? :)

[transistorgrab]

MPPT is "just software" ;) Yes MPPT is a must. I have no idea how to put this in control software but it sits above the low level stuff like current protection, voltage protection, general control for intermediate voltage, balancing output power to input power. So it must be planned from the start but requires other stuff before.

[pixelpoppul-zz]

Looks like we have a solid plan, let's just hope we don't get the magic smoke XD. 600w is doable and the spwm may need some tuning because sine waves made by the inverter will be absolutely distorted due to the loads

[HyGy]

Is there now a board/parts list to build?

It will be good if this thing is supported by ESPHome, and then we can integrate it for example to homeassistant.

I think what is required:

• battery charging (Settable parameters)
• solar input
• if there is not enough power in the batteries/solar then add suplement from the grid
• serial output/input to control/monitor the device parameters/consumption/voltages

What is a really usable a 5KV system I think. Bot for start about 700VA is good.

What is the state now?

[transistorgrab]

Hi @HyGy,

There is still no fixed parts list. Some parts of the circuit are still not finally designed yet. Additional problem that came up in the last few days when I reviewed the design is that the chosen microcontroller is currently not available anywhere. If anyone has an idea what a good and available second source is, I'm open for suggestions. I found some AVR32 based parts, PIC32 based parts even a Renesas part on digikey but I cannot say how feasable they are for this application.

Regarding ESPHome I don't think this should be integrated into the controller software. I'm more thinking about an open protocoll where an external interface-converter then implements the required protocoll for home automation. e.g. an ESP32 that talks on one end to the inverter (via wired interface) and provides the desired protocoll via WiFi. This would also solve the problem of isolation of the communication interface because the ESP32 could be connected to the hot potential of the inverter.

[Waynedejager1]

I have a vested interest in this space and would like to help where possible. My main area of interest would be in the 100KW range of product and would be willing to assist with the project. Areas where I can offer assistance :- 1) Current commercial unit damaged samples 2) Development funding once the core dev team is established 3) Procuring samples and testing in real life application.

If this appeals to you Andre @transistorgrab then please keep me informed. Wayne

[transistorgrab]

Hi @Waynedejager1,

thanks for your offer.

Currently I'm back on square 1 regarding the main controller of the device.

The one I picked when starting the project looked like the perfect candidate. However, currently it's nowhere available and I'm not a big expert on controllers to know which of the currently available parts would fit the bill. Also prices for components available now seem to be much higher than a few years ago. So, research on this is slow until I find a part that looks OK or someone comes up with a suggestion. If you know of someone who can suggest a part I gladly look into it. 😄

[vkylamba]

@transistorgrab Is it still active? I would be interested to contribute.

[transistorgrab]

Hi @vkylamba,

this project is not abandoned, thanks for your interest. :)

Current status is, that I need to find a replacement for the currently planned controller of the inverter (it's not available right now). Since I'm not familiar with many controllers I'm open for suggestions. Currently I think about changing the design so that the controller sits on a separate board so that it's easier to only change the controller depending on availability and not to have to change the whole board.

[vkylamba]

@transistorgrab thank you for the response. Based on the current controller specified in the schematics. usedMaybe one of the STM32F0x0 series microcontroller can be used, e.g. stm32f030cc. If you can list the features, I can look up the available controllers.