Solar, Wind, Hybrid Battery Charger Circuits

The article explains a dual input hybrid solar and wind battery charger circuit using cheap and ordinary components.

The idea was requested by one of the interested members of this blog.

Technical Specifications

Good after noon sir am designing a " Solar and Wind energy harvest regulator circuit" which has two inputs and one output.
The PV solar panel ( 0-21V DC) and the other input is a wind turbine (15V DC).
The circuit must be designed for charging a 12v battery . the output current being delivered to the loaded battery must not deliver more than 3.5A.
My group and myself have gotten a few circuits off the internet and simulated them using pspice none of them is giving us the output current of 3.5 A. please sir can you please help us with examples of circuits which we can use.

The Design

In one of my previous posts I introduced a similar concept which enabled a battery to be charged from two sources of energy such as wind and solar simultaneously and without the need of any manual intervention.

The above design is based on PWM concept and therefore could be a bit complex and difficult to optimize for a layman or a new hobbyist.

The circuit presented here offers exactly the same features, that is, it enables the charging of a battery from two different sources, yet keeping the design extremely simple, efficient, cheap and hassle free.

Let's understand the circuit in details with the help of the following explanation:

Circuit Diagram

The figure above shows the proposed solar, wind twin hybrid battery charger circuit, using very ordinary components such as opamps and transistors.

We can see two exactly similar opamp stages being employed, one on the left side of the battery and the other on the right side of the battery.

The left side opamp stage becomes responsible for accepting and regulating the wind energy source while the right side opamp stage processes the solar electricity for charging the single common battery in the middle.

Although the two stages look similar, the modes of regulation are different. The wind energy controller circuit regulates the wind energy by shunting or shorting the excess energy to ground, while the solar processor stage does the same but by cutting of the excess energy instead of shunting.

The above explained two modes are crucial since in wind generators which are essentially alternators require the excess energy to be shunted, and not cut off, so that the coil inside can be safeguarded from over current, which also keeps the speed of the alternator at a controlled rate.

This implies that the concept can be also implemented in ELC applications also.

How the opamp is Configured to Function

Now let's investigate the functioning of the opamp stages through the following points:

The opamps are configured as comparators where the pin#3 (non-inverting input) is used as the sensing input and pin#2 (inverting input) as the reference input.

The resistors R3/R4 are selected such that at the required battery charging voltage, pin#3 just becomes higher than pin#2 reference level.

Therefore when the wind energy is applied to the left circuit, the opamp tracks the voltage and as soon as it tries to exceed the set threshold voltage, pin#6 of the IC goes high which in turn switches ON the transistor T1.

T1 instantly short circuits the excess energy restricting the voltage to the battery at the desired safe limit. This process goes on continuously ensuring the required voltage regulation across the battery terminals.

The opamp stage at the solar panel side also implements the same function however here the introduction of T2 makes sure that whenever the solar energy is higher than the set threshold, T2 keeps on cutting it OFF, thereby regulating the supply to the battery at the specified rate, which safeguards the battery as well as the panel from unusual inefficient situations.

R4 on both the sides may be replaced with a preset for facilitating easy setting up of the threshold battery charging level.

Current Control Stage

As per the request, the current to the battery must not exceed 3.5 Amps. To regulate this a standalone current limiter can be seen attached with the battery negative.

However the design shown below can be used with up to 10 amp current, and for charging up to 100 Ah battery

This design can be built using the following circuit:

R2 may be calculated with the following formula:

• R2 = 0.7 / charging current
• wattage of the resistor = 0.7 x charging current

Parts list for the solar wind dual hybrid battery charger circuit

• R1, R2, R3, R5, R6 = 10k
• Z1, Z2 = 3V or 4.7V , 1/2 watt zener diode
• C1 = 100uF/25V
• T1, T2 = TIP142,
• T3 = BC547
• D2 = 1N4007
• Red LEDs = 2nos
• D1 = 10 amp rectifier diode or Schottky diode
• Opamps = LM358 or any similar

Simplified Solar, Windmill Hybrid Battery Charger Circuit

A very effective solar, and windmill combined hybrid battery charger can be built using just a couple of transistors, as shown in the following image:

This is actually a simple yet very effective, full fledged hybrid charging system which will not only combine the solar and windmill power to charge your battery faster, but also make sure that the battery is never over charged or over discharged. That means, your battery condition will be always maintained efficiently ensuring a longer battery life.

Another great feature of this hybrid charger is that, the load can be operated simultaneously while the battery is being charged, without loading the battery.

Also, in case the solar/wind power is unavailable and the battery reaches lower discharge level, the load will be automatically cut off, to prevent over discharging of the battery.

Double DC Input Hybrid Charger Circuit

A similar second hybrid design below describes a simple idea which enables the processing of two different sources of DC inputs derived from different renewable sources.

This hybrid renewable energy processing circuit also includes a boost converter stage which effectively raises the voltage for the required output operations  such as a charging a battery. The idea was requested by one of the interested readers of this blog.

Technical Specifications

Hi, I am a final year engineering student, i need to implement a multi input chopper (integrated buck/buck boost converter) for combining two dc sources(hybrid).

I have the basic circuit model, can you help me to design inductor, capacitor values and control circuit for the chopper. I have emailed you the circuit design.

Circuit Operation.

As shown in the figure the IC555 sections are two identical PWM circuits positioned for feeding the adjoining double input boost converter circuit.

Following functions take place when the shown configuration is switched ON:

DC1 may be assumed as the high DC source such as from a solar panel.

DC2 may be assumed as alow DC input source, such as from a wind turbine generator.

Assuming these sources to be switched ON, the respective mosfets start conducting these supply voltages across the following diode/inductor/capacitance circuit in response to the gate PWMs.

Now since the PWMs from the two stages might beset with different PWM rates, the switching response will also differ depending upon the above rates.

For the  instant when both the mosfets receive positive pulse, both the inputs are dumped across the inductor causing a high current boost to the connected load. The diodes effectively isolate the flow of the respective inputs towards the inductor.

For the instant when the upper mosfet is ON while the lower mosfet is OFF, the lower 6A4 becomes forward biased and allows the inductor a return path in response to the switching of the upper mosfet.
Similarly when the lower moset is ON, and the upper mosfet is OFF, the upper 6A4 provides the required return path for the L1 EMF.

So basically, the mosfets can be turned oN or OFF irrespective of any kind of synchronization making things pretty easy and safe. In any case the output load would receive the average (combined) intended power from the two inputs.

The introduction of the 1K resistor and the 1N4007 diode ensures that the two mosfets never receive separate logic high pulse edge, though the falling edge may be different depending upon the setting of the respective PWMs of the 555 ICs.

The inductor L1 will need to be experimented with in order to get the desired boost at the output. Different number of turns of 22 SWG super enameled copper wire may be used over a ferrite rod or slab, and the output measured for the required voltage.