Solar MPPT charge controller using ESP32

Thread Starter

Dikxita

Joined Apr 22, 2024
27
I want to design a Solar MPPT charge controller using ESP32. Input voltage from the solar is 1.5V to 3V and 15A of current. Using MPPT technique i want to charge DC loads having 5V ,5A or 5V ,3A.
I'm struggling with the implementation particularly in integrating the MPPT algorithm with the ESP32 and designing the circuitry to control the power conversion efficiency.

I would greatly appreciate any advice, resources or references you could provide to help me to move forward with this project. Whether its suggesting specific MPPT algorithm suitable for the esp32 or sharing insights on circuit design considerations, any input would be immensely valuable.
 

ericgibbs

Joined Jan 29, 2010
19,119
Hi D,
I would suggest you download the posted firmware for that ESP32 MPPT, then modify the measured voltage/current parameters to suit your project.

E
 

Thread Starter

Dikxita

Joined Apr 22, 2024
27
Hi D,
I would suggest you download the posted firmware for that ESP32 MPPT, then modify the measured voltage/current parameters to suit your project.

E
Hi Eric I went through the code, but what about the circuit changes? what are the components I will be required to change to use for my application? as in my case input voltage from the solar is 1.5V to 3V and 15A of current whereas in DIY ESP32 based dual phase interleaved MPPT it is for 100V and 30A. Please help me to understand.
 
Last edited:

fourtytwo

Joined May 16, 2022
18
I wouldn't bother with that circuit as it is a buck converter meaning vi>vo but in your case vi<vo so you need a boost converter.
MPPT is a doddle to implement in firmware, simply a task called periodically (several seconds perhaps) that uses input current & voltage plus those same values stored from the last run to adjust duty cycle accordingly. Often in noisy switching converter environments you also need some filtering of the ADC results for stable operation.

It is unfortunate your solar array voltage is so low as this will lead to inefficiencies in the converter, is there any hope of increasing your solar source voltage ?
 

Thread Starter

Dikxita

Joined Apr 22, 2024
27
I wouldn't bother with that circuit as it is a buck converter meaning vi>vo but in your case vi<vo so you need a boost converter.
MPPT is a doddle to implement in firmware, simply a task called periodically (several seconds perhaps) that uses input current & voltage plus those same values stored from the last run to adjust duty cycle accordingly. Often in noisy switching converter environments you also need some filtering of the ADC results for stable operation.

It is unfortunate your solar array voltage is so low as this will lead to inefficiencies in the converter, is there any hope of increasing your solar source voltage ?
My solar panel can give max voltage of 3V but not more than that. Could you please suggest me to build circuit for MPPT as i have already built circuit for boost controller and Battery management circuit and both are working fine. But I'm stuck at MPPT configuration. How can I merge my boost controller circuit , battery management circuit with MPPT? I haven't worked on MPPT yet. Please suggest.
 

fourtytwo

Joined May 16, 2022
18
My solar panel can give max voltage of 3V but not more than that. Could you please suggest me to build circuit for MPPT as i have already built circuit for boost controller and Battery management circuit and both are working fine. But I'm stuck at MPPT configuration. How can I merge my boost controller circuit , battery management circuit with MPPT? I haven't worked on MPPT yet. Please suggest.
It really depends upon what level of design you are capable of. You would need to replace your present boost controller with an MCU having a PWM capable of driving the output device and sufficient ADC channels to measure input voltage/current for MPPT and output voltage/current for battery charge.

Off the shelf solutions are called "solar charge controllers".
Alternatively TI have some semi-integrated solutions in there BCMxxxx series of chips (check out there website).
 

Thread Starter

Dikxita

Joined Apr 22, 2024
27
It really depends upon what level of design you are capable of. You would need to replace your present boost controller with an MCU having a PWM capable of driving the output device and sufficient ADC channels to measure input voltage/current for MPPT and output voltage/current for battery charge.

Off the shelf solutions are called "solar charge controllers".
Alternatively TI have some semi-integrated solutions in there BCMxxxx series of chips (check out there website).
I cant go ahead with my boost circuit and battery management circuit? Actually using this boards charging of loads(mobile, camera) were working. Yes off course I will be using ESp32 but cant i also use this boards for implementing MPPT ?
 

fourtytwo

Joined May 16, 2022
18
I cant go ahead with my boost circuit and battery management circuit? Actually using this boards charging of loads(mobile, camera) were working. Yes off course I will be using ESp32 but cant i also use this boards for implementing MPPT ?
Unfortunately no. The way MPPT works is to vary the load impedance to match the panels best operating point along the PV curve, to do this it would normally directly control the duty cycle of a converter.

You have not said what this existing boost converter is ?
 

Thread Starter

Dikxita

Joined Apr 22, 2024
27
Unfortunately no. The way MPPT works is to vary the load impedance to match the panels best operating point along the PV curve, to do this it would normally directly control the duty cycle of a converter.

You have not said what this existing boost converter is ?
Below is the circuit of boost convertor(TPS61088) for boosting low voltage to 5V. but it has a limitation input voltage has to be minimum 2.6V, then only it can boost to 5V.
1716467113399.png

Below is the Battery management board(IP5328P).

1716467341073.png

Combining this both boards Camera(EK700) and mobile(oppo F17 pro) are getting charged. But since input voltage is variable in this project i have to use MPPT to keep a constant input voltage. Please suggest me a way to take this project ahead.
 

fourtytwo

Joined May 16, 2022
18
Some information (spec) about your solar panel would be helpful.
If you forget about MPPT some people use 80% VOC as a suitable operating point BUT,
you would have to modify your boost converter to maintain a constant input voltage.
Some further info at a lower power level can be found here for example.
You have a very weird panel generating 15A at just a few volts, tell me more ?
 
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