How to Build A Hybrid Solar Charger And Its Applications

According to the National Renewable Energy Laboratory, the sunlight received by earth in one hour is enough to meet the annual energy needs of all people worldwide. Solar energy is suitable for heating and electricity generation using photo voltaic cells (PVC). Solar power can restrict climate change as it produces no carbon emissions. Here in this article, we will discuss on the Hybrid Solar Charger.

Solar energy is the best alternative, which can replace the fossil fuels like coal and gas for electricity generation that create air, water, and land pollution. The solar power (i.e DC form of energy) can be stored in a battery for future use.

The conversion efficiency of a solar cell is the percentage of the solar energy shining on a photo voltaic cell that is converted into usable electricity.

Hybrid Solar Charger

The efficiency of a solar charging system depends on the weather conditions. Solar panels generate the most electricity on clear days with abundant sunshine. Commonly, the solar panel gets four to five hours of bright sunlight in a day. If the weather is cloudy, it affects the battery charging process and the battery does not get a full charge.

This simple hybrid solar charger can give the solution for this problem. It can charge the battery using both solar power as well as AC mains supply. When the output from the solar panel is above 12 volts, the battery charges using the solar power and when the output drops below 12 volts, the battery charges through AC mains supply.

Hybrid Solar Charger Circuit

The below figure shows the hybrid solar charger circuit. The following hardware components required to build the hybrid solar charger circuit.

  • A 12V, 10W solar panel (connected at SP1)
  • Operational amplifier CA3130 (IC1)
  • 12V single-changeover relay (RL1)
  • 1N4007 Diodes
  • Step-down transformer X1
  • Transistor BC547 (T1)
  • Few other RLC components
Hybrid Solar Charger Circuit
Hybrid Solar Charger Circuit

10 Watt, 12 Volt Solar Panel

In this circuit, we used a 10 Watt, 12 Volt Solar Panel. It will provide enough power to charge a 12V battery.

10 Watt, 12 Volt Solar Panel
10 Watt, 12 Volt Solar Panel

This 10w-12v module is an array of 36 multi-crystalline silicon solar cells of similar performance, interconnected in series to obtain the 12-volt output.

These solar cells are mounted on a heavy duty anodized aluminium frame provides strength. For each 18 cells series strings, one bypass diode is installed. These cells are laminated between high transmissivity, low-iron, 3mm tempered glass and sheet of a Tedlar Polyester Tedlar (TPT) material by two sheets of ethylene Vinyl acetate (EVA). This setup protects against moisture penetrating into the module.

Key Features

  • 36 high-efficiency Silicon Solar Cells
  • Optimized module performance with Nominal Voltage 12 V DC
  • Bypass diodes to avoid the hot spot effect
  • Cells are embedded in a sheet of TPT and EVA
  • Attractive, stable, heavy duty anodized aluminium frames with convenient
  • Pre-cabled with fast-connecting systems

Hybrid Solar Charger Circuit Working

In sunny sunlight, the 12V, 10W solar panel delivers up to 17 volts DC with the 0.6-ampere current. The diode D1 provides reverse polarity protection and capacitor C1 buffers voltage from the solar panel. Op-amp IC1 is used as a simple voltage comparator.

Zener diode ZD1 provides a reference voltage of 11 volts to the inverting input of IC1. The non-inverting input of e op-amp gets voltage from the solar panel through R1.

The working of the circuit is simple. When the output from the solar panel is greater than or equal to 12 volts, Zener diode ZD1 conducts and provides 11 volts to the inverting terminal of IC1.

Since non-inverting input of the op-amp gets a higher voltage at this time, the output of the comparator turns high. Green LED1 glows when the comparator’s output is high.

The transistor T1 then conducts and relay RL1 energized. Thus the battery gets charged current from the solar panel through the normally-open (N/O) and common contacts of relay RL1.

LED2 indicates charging of the battery. Capacitor C3 is provided for clean switching of transistor T1. Diode D2 protects transistor T1 from back EMF and diode D3 prevents the discharge of the battery current into the circuit.

When the output from the solar panel gets down below 12 volts, the output of the comparator turns low and the relay de-energizes. Now the battery gets charged current from the transformer based power supply through the normally closed (N/C) and common contacts of the relay.

This power supply includes step-down transformer X1, rectifying diodes D4 and D5, and smoothing capacitor C4.


To test the circuit for proper functioning, the below instructions to be followed:

  • Remove the solar panel from connector SP1 and connect a DC variable voltage source.
  • Set some voltage below 12V and slowly increase it.
  • As the voltage reaches 12V and goes beyond, the logic at test point TP2 changes from low to high.
  • The transformer-based power supply voltage can be checked at test point TP3.

Applications of Hybrid Solar Charger

In recent days, the process of generating electricity from sunlight has more popularity than other alternative sources and the Photovoltaic panels are absolutely pollution free and they don’t require high maintenance. The following are some examples.

  • The Hybrid solar charger system used for multiple energy sources for providing full-time backup supply to other sources.
  • Street lights use the solar cells to convert sunlight into DC electricity charge. This system uses a solar charge controller to store DC in the batteries and uses in many areas.
  • Home systems use PV module for household applications.

So this is all about hybrid solar charger circuit design. I hope you have gone through it very well. further more information about solar energy based engineering projects or any query regarding this article please share in the comment section below.

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