open source mppt's

[sun walker]

In my search for an mppt I've come across 2 open source mppt's that I like,(unfortunately they can only handle <1000w, a bit small unless I use a lot of copper, but I prefer open source, being a Linux user, I find it superior to corporate), the 1st is a self build, a bit out of my depth, but this guy is extraordinary, well worth a listen.

DIY 1kW Arduino MPPT Solar Charge Controller (WiFi ESP32)​

TechBuilder

open source mppt at DuckDuckGo

DuckDuckGo. Privacy, Simplified.

duckduckgo.com

The other I'm tempted to invest in copper for, from Canada.

ElectroDacus

Also see/search post here

Open Source Microconverter​

Simple home made analog MPPT contoller​

I'm interested in any feedback +,-

 

[curiouscarbon]

watching thread, interested in learning about open source MPPT design and implementation.

for now i cowardly use the blue mppt ?

 

[AlpineJoe]

Very cool! Though I wonder how good the hall effect measurement works, but I guess he just needs relative measurement. Also 16 gauge wire for the inductor for 30A output? Seems small.

 

[octal_ip]

I made the TechBuilder 1kW MPPT board. It worked well for some tests, but the MPPT algorithm is somewhat simple and can get stuck on a false maximum power point. The author seems to have abandoned the project too, so it's only worth picking it up if you're able to troubleshoot any issues yourself.

Still, it makes for a cheap high power MPPT (if you value your time at $0 per hour).

 

[Warpspeed]

Just found this thread.
A super simple cheap no frills mppt controller is fairly easy to make, but there are those pedantics that are never happy with a simple solution.

Basically what we must do is control the electrical loading on the panels, so that the voltage at the panel stays pretty much at the maximum power voltage printed on the rating plate. So at dawn, at first, the voltage is allowed to rise with no load at all.
As the sun gains some strength, we can apply some load, and increase the current output into the battery, but never overload it enough to cause the voltage to fall below the optimum maximum power voltage.

If a cloud obscures the sun, we need to throttle back the loading a bit, and increase it again when the cloud has passed. Its as simple as that.

The usual way this is done is with some fancy software that starts out knowing nothing about the system, but by trial and error (perturb and observe) gradually adjusts solar panel loading to find the power peak. There is a much simpler way to do it than that, without requiring a microcontroller or any software !

Its just a case of monitoring the solar voltage and regulating that voltage with a simple voltage regulator.
In other words classic shunt voltage regulation.
We pull enough power from the solar panel to hold the voltage at the panel constant, no more, and no less. Its as simple as that.

Likewise, with a lithium battery, we keep feeding all of the available current from our shunt voltage regulator into the battery, until it reaches full rated battery voltage. We then must throttle back the current to hold a fixed battery voltage. The battery charging current then gradually ramps down to zero, and the solar panel voltage is then free to rise above the maximum power voltage.

These two functions can both be easily performed by a single ordinary high frequency pwm control chip driving a buck converter.

Its a bit like your standard bench power supply that has a fixed regulated output voltage, and an adjustable current limit.
Two distinct modes of operation that cross over.

In this case, its a constant solar panel voltage regulator, and constant battery voltage regulator. These two parameters cross over when the battery reaches its full rated voltage. Its not difficult or complicated, and it works very well.

Now the cynics will say Ah! but what about changes in temperature or solar insolation, the peak power voltage is not a precise fixed figure.
Your cheap crappy NON mppt controller idea cannot follow that !!!

True, but the actual peak power voltage does not change all that much from what is on the rating plate. And if you build it my way, its possible to tweak the solar panel voltage potentiometer up and down under load, and watch the change in bulk charging current.

You might be surprised that the power "peak" is not a peak at all, but a very broad low hump. The solar voltage is surprisingly non critical.

What DOES change is insolation. At night there is nothing. At mid day, in a clear blue sky its at maximum. Between those two extremes we have a very wide range of solar output power to track, and a simple constant voltage circuit will do that very well, and be very fast acting too.
So my idea definitely works, and is proven to work very well.

Sure, a software mppt might beat it by a very low single digit percentages, but it would not be by much more than that.
Perturb and observe algorithms can be slow to respond, and sometimes lock onto false peaks. My system is very fast and cannot be fooled.

In the great scheme of things, it has certainly proven itself here, and its ideal for a simple do it yourself project for any tinkerers here.

If you build it yourself, its also not going to cost a fortune for multiple controllers, and be repairable, something that the commercial solar controllers very rarely are.

 

[fat_old_sun]

In my search for an mppt I've come across 2 open source mppt's that I like,(unfortunately they can only handle <1000w, a bit small unless I use a lot of copper, but I prefer open source, being a Linux user, I find it superior to corporate), the 1st is a self build, a bit out of my depth, but this guy is extraordinary, well worth a listen.

​

The other I'm tempted to invest in copper for, from Canada.

ElectroDacus

I'm interested in any feedback +,-

Electrodacus is not a MPPT controller. It uses a relay to connect the panels to the batteries like a PWM but fully disconnects at absorption voltage, unlike a PWM which adjust the duty cycle to maintain the absorption voltage for a specified period.

 

[octal_ip]

Just found this thread.
A super simple cheap no frills mppt controller is fairly easy to make, but there are those pedantics that are never happy with a simple solution.

Basically what we must do is control the electrical loading on the panels, so that the voltage at the panel stays pretty much at the maximum power voltage printed on the rating plate. So at dawn, at first, the voltage is allowed to rise with no load at all.
As the sun gains some strength, we can apply some load, and increase the current output into the battery, but never overload it enough to cause the voltage to fall below the optimum maximum power voltage.

If a cloud obscures the sun, we need to throttle back the loading a bit, and increase it again when the cloud has passed. Its as simple as that.

The usual way this is done is with some fancy software that starts out knowing nothing about the system, but by trial and error (perturb and observe) gradually adjusts solar panel loading to find the power peak. There is a much simpler way to do it than that, without requiring a microcontroller or any software !

Its just a case of monitoring the solar voltage and regulating that voltage with a simple voltage regulator.
In other words classic shunt voltage regulation.
We pull enough power from the solar panel to hold the voltage at the panel constant, no more, and no less. Its as simple as that.

Likewise, with a lithium battery, we keep feeding all of the available current from our shunt voltage regulator into the battery, until it reaches full rated battery voltage. We then must throttle back the current to hold a fixed battery voltage. The battery charging current then gradually ramps down to zero, and the solar panel voltage is then free to rise above the maximum power voltage.

These two functions can both be easily performed by a single ordinary high frequency pwm control chip driving a buck converter.

Its a bit like your standard bench power supply that has a fixed regulated output voltage, and an adjustable current limit.
Two distinct modes of operation that cross over.

In this case, its a constant solar panel voltage regulator, and constant battery voltage regulator. These two parameters cross over when the battery reaches its full rated voltage. Its not difficult or complicated, and it works very well.

Now the cynics will say Ah! but what about changes in temperature or solar insolation, the peak power voltage is not a precise fixed figure.
Your cheap crappy NON mppt controller idea cannot follow that !!!

True, but the actual peak power voltage does not change all that much from what is on the rating plate. And if you build it my way, its possible to tweak the solar panel voltage potentiometer up and down under load, and watch the change in bulk charging current.

You might be surprised that the power "peak" is not a peak at all, but a very broad low hump. The solar voltage is surprisingly non critical.

What DOES change is insolation. At night there is nothing. At mid day, in a clear blue sky its at maximum. Between those two extremes we have a very wide range of solar output power to track, and a simple constant voltage circuit will do that very well, and be very fast acting too.
So my idea definitely works, and is proven to work very well.

Sure, a software mppt might beat it by a very low single digit percentages, but it would not be by much more than that.
Perturb and observe algorithms can be slow to respond, and sometimes lock onto false peaks. My system is very fast and cannot be fooled.

In the great scheme of things, it has certainly proven itself here, and its ideal for a simple do it yourself project for any tinkerers here.

If you build it yourself, its also not going to cost a fortune for multiple controllers, and be repairable, something that the commercial solar controllers very rarely are.

I've always wanted to try this approach. Anyone who monitors their MPPT closely will see that the voltage it determines to be the maximum power point doesn't vary much throughout the day - about 10% even with changing angle of the sun, cloud cover, etc. So the approach of holding a fixed array voltage (after initial calibration to determine the Vmp for your particular hardware) should work perfectly well.

The I-V curves on a typical solar panel datasheet also support this - a 10% voltage variation around the Vmp makes very little difference in actual power production, as long as you're reasonably centered on the peak.

What I have found, though, is that the largest cost of either DIY setup is usually in the inductor and capacitors, as at the end of the day they're both basically just variable buck converters. The micro-controller and current sensing hardware for the "true" MPPT doesn't add much to the BOM, so the real savings come from the DIY aspect.

 

[Warpspeed]

You are quite right.

This alternative approach fascinated me for years too, and eventually I just had to try it, and it worked better than I ever imagined it would.

I did a lot of back to back testing with two identical sets of panels (my main system split in half) and a Make Sky Blue MPPT controller connected to a pair of Turnigy power meters, both charging the same battery.
Swapping around panels and power meters in various combinations, the results were always within a very few percent either way.
Neither system was significantly superior to the other.

In the end, it came down to the power components, the mosfets and series inductor in the buck converter.
The improvement in power conversion efficiency with larger power components rapidly gets into diminishing returns.
There is no great difference between the two very different algorithms, and exactly as you say, a microcontroller costs no more these days than a direct simple PWM control chip.

I think it comes down to the microcontroller potentially being able to have more features, versus the more basic approach being a much simpler to build and repair controller, especially for those that are software challenged. The commercial units are difficult if not impossible to repair, as no circuits are available.
A further advantage of building your own controller would be a controller for higher voltages.
Higher voltage commercial mppt controllers seem to be pretty thin on the ground.

There is a thread here somewhere about all this, including schematics and some pictures of my controller, and the testing results.
I could not find it earlier.
Ah just found it !
https://diysolarforum.com/threads/simple-home-made-analog-mppt-contoller.47057/

 

[sun walker]

You are quite right.

This alternative approach fascinated me for years too, and eventually I just had to try it, and it worked better than I ever imagined it would.

I did a lot of back to back testing with two identical sets of panels (my main system split in half) and a Make Sky Blue MPPT controller connected to a pair of Turnigy power meters, both charging the same battery.
Swapping around panels and power meters in various combinations, the results were always within a very few percent either way.
Neither system was significantly superior to the other.

In the end, it came down to the power components, the mosfets and series inductor in the buck converter.
The improvement in power conversion efficiency with larger power components rapidly gets into diminishing returns.
There is no great difference between the two very different algorithms, and exactly as you say, a microcontroller costs no more these days than a direct simple PWM control chip.

I think it comes down to the microcontroller potentially being able to have more features, versus the more basic approach being a much simpler to build and repair controller, especially for those that are software challenged. The commercial units are difficult if not impossible to repair, as no circuits are available.
A further advantage of building your own controller would be a controller for higher voltages.
Higher voltage commercial mppt controllers seem to be pretty thin on the ground.

There is a thread here somewhere about all this, including schematics and some pictures of my controller, and the testing results.
I could not find it earlier.
Ah just found it !
https://diysolarforum.com/threads/simple-home-made-analog-mppt-contoller.47057/

Thanks so much, this may be what I'm looking for, but circuitry is new to me, so diffidently a challenge.
It's going to take a while to digest.
I'm upgrading a small, simple, reliable pwd system to 7.5 kw.
I've come stuck over the last several months on the mppt's purchase. The cheap ones are unreliable & the expensive ones seem over priced, either way they all seem problematic, non repairable, periodic software updates, loads of extra's etc which cobbles up all your time.
I can see the attraction of mid-high priced mppt's, you can spend your life watching all the parameters, a personal weather station & then you can watch your mates in a distant land. But Why?
I just want to set up a basic reliable larger system & then forget about it for 10 years till I need to replace my batteries.
I'd rather be surfing.

 

[Warpspeed]

Some people feel they need a solar controller with wi-fi, and full data logging and full control over the internet, with a high resolution touch screen and sexy graphics.
All I wanted was something pretty basic to efficiently track changing solar conditions, and charge my battery......
Something cheap enough to build several of them and have some spares on hand.