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Arduino based MPPT solar charge controller

ronsimpson

Well-Known Member
Most Helpful Member
#2
Please find out:
>What battery are you charging? Voltage? Charge current?
>Where is the power coming from? Solar? What voltage? Current?

Please make a diagram of what functions you need.
>Do you need to measure current? What/which current?
>Measure voltage? Which voltages?
>Measure power?
>Do you need to limit voltage and/or current?
>>How will you do that?

Arduino:
>Do you know how to measure voltage, current, power?

When do you have to be done?
 
#3
12volt 45ah battery , power from solar
there will be 2 pannals of 250 watt.
i want to measure incoming current , voltage from solar and also measure voltage and current from mppt charger to battry.
and i want to keep constant voltage at 12 volt and maximize the current
 

ronsimpson

Well-Known Member
Most Helpful Member
#4
i want to keep constant voltage at 12volt and maximize the current
I don't know what type of battery but many 12v batteries charge at 13 to 14 volts.

What is the panel voltage?
If you can get 500 watts from your two panels then that is about 40A into the battery. What is the battery maximum charging current?
What is the battery part number? Different types of batteries require different types of controllers.

You really have two projects.
1) MPP from the panel
2) Battery charger. (It is important to not over charge the battery) With in the battery charger you might want to include a "battery discharged" detector. It is important to cut off the load when the battery is empty.
----edited----
You need to get the data sheet for the panels and for the batteries.
 

ronsimpson

Well-Known Member
Most Helpful Member
#6
One panel = 20V, 16A = 320 watts. ??

I do not have a data sheet but many panels measure current at 0V and measure voltage a 0A. Which is not right (I think).
I found a panel like this:
Voltage = 21.6V at 0A, Current = 15.11A at 0V
At MPT 17.64V, 14.17A =250W.
So when you are charging at MPT and very bright Sun then the current will be 14A x 2 = 28A (two panels).
If you are using a PWM to change the voltage/current then: 17.64V, 14.17A from the panel will become 14V, 17.8A on the battery. (x2 for two panels)
 

Pommie

Well-Known Member
Most Helpful Member
#7
Is there an equation to calculate max power at any level of illumination? Just curious.

Mike.
 

ronsimpson

Well-Known Member
Most Helpful Member
#8
I think there is a way to guess the MPP. It will be different for every panel.

What we did:
Every 10 seconds we increased/decreased the charge current and measured the power. This is constantly hunting for the best point.
 

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