Solar charge controller circuit. Solar Battery Charge Controller

The controller is very simple and consists of only four parts.

it powerful transistor(I use IRFZ44N can withstand current up to 49Amps).

Automotive relay-regulator with positive control (VAZ "classic").

Resistor 120 kOhm.

The diode is more powerful in order to hold the current given off by the solar panel (for example, from an automobile diode bridge).

The principle of operation is also very simple. I am writing for people who do not understand electronics at all, since I myself do not understand anything in it.

The relay regulator is connected to the battery, minus to the aluminum base (31k), plus to (15k), from the contact (68k), the wire through the resistor is connected to the gate of the transistor. The transistor has three legs, the first is the gate, the second is the drain, the third is the source. The minus of the solar panel is connected to the source, and the plus to the battery, from the drain of the transistor, the minus of the solar panel goes to the battery.

When the relay-regulator is connected and working, then the positive signal from (68k) unlocks the gate and the current from the solar panel flows through the source-drain into the battery, and when the voltage on the battery exceeds 14 volts, the relay-regulator turns off the plus and gate of the transistor, discharging through a resistor closes to minus, thereby breaking the negative contact of the solar panel, and it turns off. And when the voltage drops a little, the relay-regulator will again give a plus to the gate, the transistor will open and again the current from the panel will flow into the battery. A diode on the positive SB wire is needed so that the battery does not discharge at night, since without light the solar panel itself consumes electricity.

Below is a visual illustration of the connection of the controller elements.

I am not strong in electronics and maybe there are some flaws in my circuit, but it works without any settings and works right away, and does what factory controllers for solar panels do, and the cost is only about 200 rubles and an hour of work.

Below is a not entirely clear photograph of this controller, so roughly and sloppy just all the details of the controller are fixed on the box body. The transistor heats up a little and I fixed it on a small fan. In parallel with the resistor, I put a small LED that shows the operation of the controller. When the SB is on, it is connected, when it is not, the battery is charged, and when the battery blinks quickly, the battery is almost charged and is simply being recharged.

This controller has been working for more than six months and during this time there have been no problems, I connected it and that's it, now I don't monitor the battery, everything works by itself. This is my second controller, the first one I assembled for wind turbines as a ballast regulator, see about it in previous articles in the section of my homemade products.

Attention - the controller is not fully functional. After some time of operation, it turned out that the transistor in this circuit is not completely closed, and current continues to flow into the battery even if 14 volts are increased

And now I have a ballast regulator as a controller, which has been working fine for a long time. As soon as the voltage exceeds 14 volts, the transistor opens and turns on the light bulb, which burns all excess energy. At the same time, there are now two solar panels and a wind generator on this ballast.

This time I decided to make a machine that automatically turns on the LED lighting in garden gazebo. Since there is no power outlet nearby, and the constant pulling of the extension cord is quite a tedious task, I decided to power the LEDs from a battery with recharging from solar cells.

A very similar one was previously described, which illuminates a glass shelf in a closet. There would be a problem using this driver, because we need more light to illuminate the gazebo than to illuminate the glass shelf. Also, the use of a more powerful light source will discharge the battery faster, which can fail as a result of deep discharge of the cells in the battery.

To prevent this, I decided to create a simple driver with protection against too deep discharge of the battery based on . In turn, the solar cells also serve as a light sensor, which greatly simplifies the whole circuit.

The printed circuit board measures 40mm by 45mm. In addition, two mounting holes have been added. The whole device is powered by three Ni-MH batteries (1.2V/1000mAh). For charging, a solar battery with a nominal voltage of 5 volts and a maximum output current of up to 80 mA is used. The solar battery charges the batteries through rectifier diode D1. The circuit does not have battery overcharge protection due to the fact that in this configuration, overcharging is simply not possible.

A fully charged battery should have a voltage of about 4.2-4.35 V. The solar panel produces a voltage of 5 V, but there is a drop in the rectifier diode in the region of 0.7 V, which gives us a voltage of 4.3 V. Transistor Q1 is responsible for turning on the lighting in night time and turn it off during the day. The base of this transistor is connected through a 2.2 kΩ resistor to the positive pole of the solar array.

When the solar array is not generating electricity, or it is too small, transistor Q1 is turned off. Then the current from the output (“REF”) of the zener diode TL431 will flow only through the resistor R4, which creates a voltage divider along with resistors R2 and R3. Transistor Q2 drives the load in the form of LEDs. For the circuit to work correctly, we cannot ignore the resistor R5, whose task is to pull the base of the transistor Q2 to the plus of the power supply.

According to the calculations for the available voltage, it turns out that the resistor should have a resistance of 100 ohms. With this resistance, the circuit switches very quickly. But the problem is that this resistor has enough small value, and a very large current flows through it. The total current consumption is about 23 mA! I decided to replace this resistor with a larger value resistor. As a result, I put a resistor with a nominal value of 1 kOhm. Now the load shedding is not so fast, but the current consumption has been reduced to 8mA.

Of course, the current value of 8 mA is only consumed when the solar panel is in a dark place - that is, only at night when the LEDs are on. And this is the same maximum current (8 mA) that comes from the battery at a voltage of 4.2 V. I set the load off voltage to 2.9 V. The voltage limit for one cell is 0.9 V, which when connected in series with three gives us 2.7 V, and therefore we still have 0.2 V to spare.

The circuit after disconnecting the load (ie at 2.9 V and below), consumes only 50 µA. The same current will be when the solar panel charges the batteries. The device is very responsive to light, but not so much that street lighting would interfere with twilight. Approximately 2 minutes pass from the moment the sunset is detected until the LEDs turn on at 100%.

By removing transistor Q1, resistor R1 and rectifier diode D1 from the system, we get a simple circuit for protecting the battery from deep discharge. A similar circuit can be used to disconnect a Li-Ion or Li-Pol battery from charging. It can be used, for example, in a flashlight. It is also possible to create such protection for other voltages, for this you need to calculate the voltage divider. There are formulas and an example of calculation

If you have been thinking about an alternative way to get energy and decided to install solar panels, then you probably want to save money. One of the savings opportunities is make your own charge controller. When installing solar generators - panels, it takes a lot of additional equipment: charge controllers, batteries, for transferring current to technical standards.

Consider manufacturing do-it-yourself solar battery charge controller.

This is a device that controls the level of charge of lead-acid batteries, preventing them from being completely discharged and recharged. If the battery begins to discharge in emergency mode, the device will reduce the load and prevent complete discharge.

It is worth noting that a self-made controller cannot be compared in quality and functionality with an industrial one, but it will be quite sufficient for the operation of the electrical network. On sale come across products made in the basement, which have a very low level of reliability. If you do not have enough money for an expensive unit, it is better to assemble it yourself.

DIY solar battery charge controller

Even a homemade product must meet the following conditions:

• 1.2P< U x I , где P – общая мощность всех используемых источников напряжения, I – ток прибора на выходе, U – вольтаж системы при разряженных батареях
• The maximum allowed input voltage must be equal to the total voltage of all batteries without load.

In the image below you will see a diagram of such electrical equipment. In order to assemble it, you will need a little knowledge in electronics and a little patience. The design has been slightly modified and now a field-effect transistor is installed instead of a diode, which is regulated by a comparator.
Such a charge controller will be sufficient for use in low power networks, using only. Differs in simplicity of production and low cost of materials.

Solar charge controller works on simple principle: when the voltage on the drive reaches the specified value, it stops charging, only drip charging continues. If the indicator voltage drops below the set threshold, the current supply to the battery is resumed. The use of batteries is disabled by the controller when the charge in them is less than 11 V. Thanks to the operation of such a regulator, the battery will not spontaneously discharge during the absence of the sun.

Main characteristics charge controller circuits:

• Charge voltage V=13.8V (configurable), measured when there is a charge current;
• Load shedding occurs when Vbat is less than 11V (configurable);
• Turning on the load when Vbat=12.5V;
• Temperature compensation of charge mode;
• The economical TLC339 comparator can be replaced with the more common TL393 or TL339;
• The voltage drop on the keys is less than 20mV when charging with a current of 0.5A.

Advanced Solar Charge Controller

If you are confident in your knowledge of electronic equipment, you can try to assemble a more complex charge controller circuit. It is more reliable and is able to run on both solar panels and a wind generator that will help you get light in the evenings.

Above is an improved do-it-yourself charge controller circuit. To change the threshold values, tuning resistors are used, with which you will adjust the operating parameters. The current coming from the source is switched by the relay. The relay itself is controlled by a field effect transistor key.

All charge controller circuits tested in practice and have proven themselves over the course of several years.

For summer cottages and other objects where a large consumption of resources is not required, it makes no sense to spend money on expensive elements. If you have the necessary knowledge, you can modify the proposed designs or add the necessary functionality.

So you can DIY a charge controller when using devices alternative energy. Do not despair if the first pancake came out lumpy. After all, no one is immune from mistakes. A little patience, diligence and experimentation will bring the matter to an end. But a working power supply will be an excellent reason for pride.

One of the most important components solar system is the charge controller. It can be supplied separately or bundled with an inverter. As the name implies, this device is designed to control the battery charge, that is, charge controllers for a solar battery monitor the voltage level on the battery and serve to prevent the battery from being completely discharged or recharged.

The age of global accessibility, when you can find absolutely any product and information, allows you not only to purchase controllers in any specialized store, but also to assemble it yourself. To do this, you will need a diagram of the device that you plan to make, in our case, a charge controller, and the ability to understand electronics. We will try to supply you with both.

Charging controllers for SB: brief description

There are several varieties of the described device. The simplest of them performs only one function: turns the batteries on and off depending on their charge. More "advanced" models are equipped with a maximum power point tracking function, which provides a higher output current compared to the solar panel current. And this, in turn, increases the efficiency of the entire installation as a whole.

More advanced models are able to lower the voltage on the SB and maintain it at the required level. The presence of this function contributes to a more complete charging of the battery.

Any controller, including a homemade one, must meet certain requirements:

• 1.2P ≤ I×U, where P is the total power of the solar panels of the entire system; I – controller output current; U - system voltage with discharged batteries.
• 1.2Uin = Ux.x, where Uin is the maximum allowable input voltage, Ux.x is the total open-circuit voltage of all solar panels in the system.

If you can't buy...

Of course, often a do-it-yourself device will be worse than a similar device manufactured at the factory. But today, few people can be trusted. And cheap solar controllers shipped from China could also be assembled in some back room. So why buy a device of which you are not sure if it is possible to build it at home.

Figure 1 shows the simplest circuit, using which you can assemble a controller with your own hands, suitable for charging a 12 V lead-acid battery using a low-power SB with a current of several amperes. By changing the values ​​of the elements used, you can adapt the assembled device to the battery with other technical specifications. It should be noted that this scheme involves the use of a field effect transistor controlled by a comparator instead of a protective diode.

Video to help you:

The principle of operation is quite simple: when the voltage on the battery reaches the set value, the controller will stop charging, if it drops below the threshold value, charging will be turned on again. At a voltage of less than 11 V, the load will be turned off, and at a voltage of more than 12.5 V, on the contrary, it will be connected to the battery. This small device will save your battery from spontaneous discharge in the absence of the sun. Figure 2 shows an already assembled kit, consisting of two batteries, DC / DC converters and an indication.

Self-assembled solar charge controllers according to more complex schemes can guarantee you reliable and stable operation. Therefore, if you feel the strength in yourself, then another diagram is presented below. It consists of a larger number of components, but it functions without “glitches” (Figure 3).

A self-made controller assembled according to this scheme is suitable for a power supply system that operates both from a SB and from a wind generator. The signal that comes from the source of alternative energy used is switched by a relay, which in turn is controlled by a field-effect transistor switch. Trimmer resistors are used to adjust the mode switching thresholds.

Do not be afraid to experiment, because the best minds of mankind also made mistakes and falls, so if the first time you did not manage to assemble a reliable controller with your own hands, do not despair. Try again, and perhaps the second time you will succeed. But you will be “warmed up” by the very realization that you made it yourself.

The article was prepared by Abdullina Regina

How to modify the device for charge control:

In solar power plant systems, various connection schemes are used to supply the received energy, which are made on different algorithms based on microprocessor electronics technology. Based on such schemes, devices called controllers for solar panels have been created.

Operating principle

There are several methods for transferring electricity from solar cells to a battery:

• Without the use of switching and adjustment devices, directly.
• Through the controllers

The first way causes the passage electric current from the source to the batteries to increase their voltage. First, the voltage will rise to a certain limit value, which depends on the type and variety of the battery design and the temperature of the external environment. Further exceed this level.

In the initial period, the battery charging is normal. Then processes begin, characterized by negative moments: the charging current continues to flow, causes an increase in voltage above the permissible value, overcharging occurs, and as a result, the temperature of the electrolyte rises. This leads it to boiling and the release of water vapor with significant intensity from the individual battery cells. This process can continue until the jars dry. It is clear that the battery life of the batteries does not increase from this phenomenon.

To limit the charge current, use special devices - charge controllers, or do it manually. Almost no one uses the latter method, since it causes inconvenience to monitor the voltage value on the instruments, to make manual switching, it is required to appoint a special worker for this to service the controllers for solar panels.

The order of the controller during charging

Controllers for solar panels are manufactured in various modifications according to the principles and complexity of the voltage limiting method:

• Easy turning off and on. controller switches Charger to the battery depending on the voltage value at the terminals.
• Transformations.
• High power control.

The first principle of simple switching

This is the simplest type of work, but it is less reliable. The main disadvantage of the method is that when the voltage at the battery terminals increases to the maximum value, the final charge does not occur. The charge reaches 90% of the nominal value. Batteries are constantly in a state of undercharging. This adversely affects their service life.

Pulse Width Principle

Such devices are made on the basis of microcircuits. They control the power unit to maintain the input voltage in a certain interval with feedback signals.

Controllers with pulse-width control have the ability to:

• Measure the electrolyte temperature in a remote or built-in battery.
• Form temperature compensation by charging voltage.
• Adapt to the properties of a particular type of battery with different values according to the voltage chart.

The more functions built into solar controllers, the higher their reliability and cost.

solar battery schedule

Highest power point voltage limit

These devices can also work in a pulse-width manner. Their accuracy is high, since the maximum value of the power given by the solar battery is taken into account. The power value is calculated and stored.

For solar cells with a voltage of 12 volts, the maximum power is at 17.5 volts. A simple controller will turn off the battery charge already at 14 V, and a controller with special technology allows you to use a supply of solar panels up to 17.5 volts.

The more the battery is discharged, the greater the loss of energy from solar cells, solar controllers reduce these losses. As a result, the controllers, using pulse-width transformations, increase the energy output of the solar battery on all charging cycles. The percentage of savings can reach up to 30%, depending on various factors. The battery output current will be higher than the input current.

Properties

When choosing the type of controller, you need to pay attention not only to the principles of operation, but also to the conditions intended for its operation. These device indicators are:

• Input voltage value.
• The value of the total power of solar cells.
• Type of load.

Voltage

The controller circuit can be powered by several batteries, which are connected in different ways. For the correct functioning of the device, it is necessary that the total voltage value, together with idling, does not exceed the limit specified by the manufacturer in the instructions.

Let's name some factors due to which it is necessary to make a 20% voltage margin:

• It is necessary to take into account the factor of advertising overestimation of the controller data.
• The processes occurring in photocells are unstable, with excessive solar flashes of light, the energy that creates the battery idle voltage can be exceeded.

Solar battery power

This value is important in the operation of the controller, since the device must have sufficient power to transfer it to the batteries, if there is not enough power, the device circuit will fail.

To calculate the power, the value of the output current from the controller is multiplied by the voltage that is generated, not forgetting the 20% reserve.

Type of load

The controller must be used for its intended purpose. You do not need to use it as a normal voltage source, connect various household devices to it. Maybe some of them will work fine, and will not disable the controller.

Another question is how long this will continue. The device works on the principle of pulse-width transformations, uses microprocessor manufacturing technologies. These technologies take into account the load inherent in the properties of the battery, and not various kinds of consumers that have peculiar properties of behavior when the load changes.

How to make a controller with your own hands

To make such a device, it is enough to have some knowledge of electrical engineering and electronics. A homemade device will be inferior to an industrial design in terms of features and efficiency, but for simple networks with low power, such a homemade controller is quite suitable.

The homemade controller must have the following parameters:

• 1.2 P ≤ I × U. In this expression, the designations of the total power of the sources (P), the controller output current (I), and the voltage with a discharged battery (U) are used.
• The highest input voltage of the controller must correspond to the total voltage of the batteries at idle without load.

A simple diagram of a homemade controller module:

Self-assembled solar controllers have the following properties:

• Charge voltage - 13.8 volts, varies from the rated current.
• Breaking voltage - 11 volts, can be adjusted.
• Switching voltage - 12.5 volts.
• The voltage drop on the keys is 20 millivolts at a current of 0.5 A.

Controllers for solar batteries are part of any solar systems, as well as systems based on solar batteries and wind generators. They make it possible to create a normal battery charging mode, increase efficiency and reduce wear, and can be assembled on their own.

Analysis of the controller circuit for hybrid power

For example, we will consider a source of emergency lighting or a burglar alarm operating around the clock.

The use of solar battery energy makes it possible to reduce the consumption of electrical energy from the central supply network, as well as to protect electrical devices from the possibility of rolling power cuts.

At night, when there is no sunlight, the system switches to mains power 220 volt. The backup source was a 12 volt battery. This system works in any weather.

Scheme of the simplest controller

The photoresistor controls transistors T1 and T2.

During the day, when there is sunlight, the transistors turn off. A voltage of 12 volts is supplied to the battery from the panel through diode D2. It prevents the battery from being discharged through the panel. With sufficient lighting, the panel produces a current of 15 watts, 1 ampere.

When the batteries are fully charged up to 11.6 volts, the zener diode opens and the red LED (LED Red) turns on. When the voltage at the battery contacts drops to 11 volts, the red LED turns off. This means that the battery needs to be charged. Resistors R1 and R3 limit the current of the LED and zener diode.

At night, or in the dark, when there is no light from the sun, the resistance of the photocell decreases, transistors T1 and T2 are connected. The battery receives its charge from the power supply. The charge current from the 220 volt power line through a transformer, rectifier, resistor and transistors goes to the battery. Capacitance C2 smooths out mains voltage ripples.

The limit of the luminous flux, at which the photosensor is turned on, is adjusted with a variable resistor.