15 Ampere solar charge controller without microcontroller

15 Ampere solar charge controller without microcontroller, In this article you will learn following things:

  • What is solar charge controller?
  • How to design solar charge controller?
  • How to select solar charge controller?
  • Circuit diagram of 15A solar charge controller?
  • Working of solar charge controller.

What is solar charge controller?

Solar charge controller is an electronics device connected between battery and solar panels. It is used to regulate charges flow from solar panels towards battery. In other words solar charge controller is used to control flow of charges from solar panels to battery. It provide protection from overflow of charges from solar panels to battery and it is also used to protect batteries from under voltages. Its mean solar charge controllers provide protection against under and over voltages of batteries in charging and discharging of batteries.

How to design solar charge controller ?

Many methods have been developed for solar charge controllers. Many types of solar charge controllers are available in market. But mainly three type of solar charge controllers are used.

  1. Simple solar charge controller: This type of solar charge controllers use analog electronics to control flow of charges.
  2. PWM based solar charge controllers: This type of solar charge controllers used microcontrollers to charge batteries through pulse width modulation method.
  3. MPPT solar charge controllers: MPPT stands for maximum power point tracking. This type of charge controller used MPPT techniques to charge battery from solar panels.

I have seen many people searching on different websites about solar charge controllers. But they don’t know about use of microcontrollers. All high rating solar charge controllers use microcontrollers. So I decided to post an articles on solar charge controller without microcontroller. In this article I am going to post a circuit diagram of 15 Ampere solar charge controller which do not use any microcontroller. This is very simple circuit diagram of charge controllers.

How to select solar charge controller ?

Before making or purchasing any charge controller for your solar panels, the question must come into your mind. What should be the rating of your charge controller? Let me give you one example, after this example you will get th answer of this question. For example you have 200 watt solar panels which have open-circuit voltage of 24volt and closed circuit voltage would be around 18 volt. By using simple power formula you can calculate rating of required charge controller for your solar panel.  You know about power formula for DC power that is

P = V * I;




we know the values of power and voltage which is P = 200W and V = 18 V. By putting above values in power formula:

I = 200 / 18 = 11.11 Ampere

So calculated value of current is 11.11A. Lets suppose voltage of solar panels may reduce to lower value 15 volt. In that case current will increase. So you should select charge controller of little higher value than calculated. I hope you got the answer of  question “How to select solar charge controller”.

Circuit diagram of 15A solar charge controller :

Circuit diagram of 15A solar charge controller is shown below. If you want to use this circuit for higher rating, you can use more than one solar charge controller in series to increase current rating of charge controller. Circuit diagram shown below is simplest circuit diagram of charge controller. Because It do not have any microcontroller. This circuit of charge controller used analog electronics instead of digital electronics.

15A solar charge controller using LM358

15A solar charge controller using LM358

Components list :

Category,Reference,Value,Order Code
Resistors,"R1",4.7k,
Resistors,"R2",4.7k,
Resistors,"R3",10k,
Resistors,"R4",18k,
Resistors,"R5",100k,
Resistors,"R6",15k,
Resistors,"R7",12k,
Resistors,"R8",33k,
Resistors,"R9",22k,
Capacitors,"C1",2.2nF,
Capacitors,"C2",10uF,
Integrated Circuits,"U1",LM358,
Transistors,"Q1",RFP30P05,
Transistors,"Q2",BC337,
Diodes,"D1",LED,
Diodes,"D2",MBR1645,
Diodes,"D3",5.1V,
Miscellaneous,"J1",Solar panel,
Miscellaneous,"J2",BATTERY,
Miscellaneous,"RV1",5k,

Working of solar charge controller:

15 ampere charge controller circuit diagram used analog electronics components to control the flow of charges from solar panel to battery. RFP30P05 P-channel MOSFET is used to charge battery. RFP30P05 MOSFET have about 20A rating. Its mean this MOSFET can easily pass current upto 20 ampere. For more information check data sheet of RFP30P05.

LM358 operational amplifier is used to turn on or off P channel MOSFET when battery is charged upto 13.6 volt. When battery is charged upto 13.6 volt. LM358 turn off MOSET by giving low signal to resistor R4. LM358 is used as comparator which compare battery voltage through voltage dividers connected to inverting and non-inverting pin of LM358 operational amplifier. Connect solar panel to connector J1 and battery terminals with connector J2. LED D1 shows the status of charging.

Thanks for reading solar charge controller article. Kindly share this article with your friends also. If you want to get updates of my every post in your inbox. Subscribe to my blog. Happy learning 🙂

14 Comments

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