Solar charge controllers

Assembly, tilt angle

We will briefly describe the installation itself, how to connect solar panels, since fastenings and other nuances are also separate topics. Installation consists in fixing the panels on the frame, there are several types of clamps, brackets: on slate, on metal, on tiles, hidden on the roof sheathing.

Support rails, clamps, clamps (end and center) rails are purchased or included in the kit for the selected installation option.

The connecting butt elements create a frame from the fixing rails.Terminal elements and holders for cores are also used - they combine aluminum frames and ground them, fix cables.

If the installation is made on a roof with a slope, then the optimal angle for panels of 30 ... 40 ° in northern latitudes is greater, for example, 45 °. In general, for self-cleaning of modules by rain, the angle should be from 15°.

The indicated positions are created by supporting profiles, often making a convenient collapsible, adjustable, rotating structure.

With uneven illumination of the array, the panel in a brighter place gives out more current, which is partially spent on heating the less loaded SB. To eliminate this phenomenon, cut-off diodes are used, soldered between the planes from the inside.

Principle of operation

If there is no current from the solar battery, the controller is in sleep mode. It does not use any of the watts from the battery. After sunlight hits the panel, electric current begins to flow to the controller. He must turn on. However, the indicator LED, together with 2 weak transistors, turns on only when the voltage reaches 10 V.

After reaching this voltage, the current will pass through the Schottky diode to the battery. If the voltage rises to 14 V, the amplifier U1 will start to work, which will turn on the MOSFET transistor. As a result, the LED will go out, and two non-powerful transistors will close. The battery will not charge. At this time, C2 will be discharged. On average, it takes 3 seconds. After the capacitor C2 is discharged, the hysteresis U1 will be overcome, the MOSFET will close, and the battery will begin to charge. Charging will continue until the voltage rises to the switching level.

Charging happens intermittently.At the same time, its duration depends on what the charging current of the battery is and how powerful the devices connected to it are. Charging continues until the voltage reaches 14 V.

The circuit turns on in a very short time. Its inclusion is affected by the charging time of C2 by the current, which limits the transistor Q3. The current cannot be more than 40 mA.

Types

On/Off

This type of device is considered the simplest and cheapest. Its only and main task is to turn off the charge to the battery when the maximum voltage is reached to prevent overheating.

However, this type has a certain disadvantage, which is to turn off too early. After reaching the maximum current, it is necessary to maintain the charge process for a couple more hours, and this controller will immediately turn it off.

As a result, the battery charge will be around 70% of the maximum. This negatively affects the battery.

PWM

This type is an advanced On/Off. The upgrade is that it has a built-in pulse-width modulation (PWM) system. This function allowed the controller, when the maximum voltage was reached, not to turn off the current supply, but to reduce its strength.

Because of this, it became possible to almost completely charge the device.

MPRT

This type is considered the most advanced at the present time. The essence of his work is based on the fact that he is able to determine the exact value of the maximum voltage for a given battery. It continuously monitors the current and voltage in the system. Due to the constant acquisition of these parameters, the processor is able to maintain the most optimal values ​​​​of current and voltage, which allows you to create maximum power.

Instructions for use

Before studying the instructions for using the controller, it is necessary to remember three parameters that must be observed when operating these electronic devices, these are:

1. The input voltage of the device should be 15 - 20% higher than the open circuit voltage of the solar panel.
2. For PWM (PWM) devices - the rated current must exceed by 10% the short-circuit current in the lines for connecting energy sources.
3. MPPT - The controller must match the capacity of the system, plus 20% of this value.

For successful operation of the device, it is necessary to study the instructions for its operation, which are always attached to such electronic devices.

The instruction informs the consumer about the following:

Safety requirements - this section defines the conditions under which the operation of the device will not lead to electric shock to the consumer and other negative consequences.

Here are the main ones:

• Before installing and configuring the controller, it is necessary to disconnect the solar panels and batteries from the device by means of switching devices;
• Prevent water from entering the electronic device;
• Contact connections must be tightly tightened in order to avoid heating during operation.
• Technical characteristics of the device - this section allows you to select a device according to the requirements for it in a specific circuit and installation location.

As a rule, this is:

• Types of adjustments and settings of the device;
• Operating modes of the device;
• Describes the controls and displays of the device.
• Methods and place of installation - each controller is mounted in accordance with the requirements of the manufacturer, which allows you to operate the device for a long time and with guaranteed quality.

Information is given on:

• The location and spatial arrangement of the device;
• The overall dimensions are indicated up to engineering networks and devices, as well as elements of building structures, in relation to the mounted device;
• Mounting dimensions are given for the mounting points of the device.
• Methods of inclusion in the system - this section explains to the consumer to which terminal and how, the connection should be made in order to start the electronic device.

Reported:

• In what sequence should the device be included in the working circuit;
• Invalid actions and measures are indicated when the device is turned on.
• Setting up the device is an important operation on which the operation of the entire scheme of a solar power plant depends, its reliability.

This section tells you how to:

• Which indicators and how signal the mode of operation of the device and its malfunctions;
• Information is given on how to set the desired operating mode of the device by time of day, load modes and other parameters.
• Types of protection - in this section it is reported from which emergency modes the device is protected.

Alternatively, this could be:

• Short circuit protection in the line connecting the device with the solar panel;
• Overload protection;
• Short circuit protection in the line connecting the device with the battery;
• Incorrect connection of solar panels (reverse polarity);
• Incorrect battery connection (reverse polarity);
• Device overheating protection;
• Protection against high voltage caused by a thunderstorm or other atmospheric phenomena.
• Errors and malfunctions - this section explains how to proceed if for some reason the device does not work correctly, or does not work at all.

The relationship is considered: a malfunction - a possible cause of a malfunction - a way to eliminate the malfunction.

• Inspection and maintenance - this section provides information on what preventive measures must be taken to ensure trouble-free operation of the device.
• Warranty obligations - indicates the period during which the device can be repaired at the expense of the device manufacturer, provided that it is used correctly, in accordance with the operating instructions.

Varieties

Today there are several types of charge controllers. Let's consider some of them.

MPPT controller

This abbreviation stands for Maximum Power Point Tracking, that is, monitoring or tracking the point where power is maximum. Such devices are able to lower the voltage of the solar panel to the voltage of the battery. In this scenario, the current strength on the solar battery decreases, as a result of which it is possible to reduce the cross-section of wires and reduce the cost of construction. Also, the use of this controller allows you to charge the battery when there is not enough sunlight, for example, in bad weather. or early in the morning and in the evening. It is the most common because of its versatility. Used for serial connection. The MPPT controller has a fairly wide range of settings, which ensures the most efficient charging.

Device Specifications:

• The cost of such devices is high, but it pays off when using solar panels over 1000 watts.
• The total input voltage to the controller can reach 200 V, which means that several solar panels can be connected in series to the controller, up to 5 on average. In cloudy weather, the total voltage of the panels connected in series remains high, which ensures uninterrupted power supply.
• This controller can work with non-standard voltage, for example, 28 V.
• The efficiency of MPPT controllers reaches 98%, which means that almost all solar energy is converted into electrical energy.
• Ability to connect batteries of various types, such as lead, lithium-iron-phosphate and others.
• The maximum charge current is 100 A, with a given current value, the maximum power output by the controller can reach 11 kW.
• Basically, all models of MPPT controllers are capable of operating at temperatures from -40 to 60 degrees.
• To start charging the battery, a minimum voltage of 5 V is required.
• Some models have the ability to simultaneously work with a hybrid inverter.

Controllers of this type can be used both in commercial enterprises and in country houses, as there are various models with different performance. For a country house, an MPPT controller with a maximum power of 3.2 kW, with a maximum input voltage of 100 V, is suitable. Much more powerful controllers are used in large volumes.

PWM controller

The technology of this device is simpler than MPPT.The principle of operation of such a device is that while the battery voltage is below the limit of 14.4 V, the solar battery is connected to the battery almost directly, and the charge occurs quickly enough, after the value is reached, the controller will lower the battery voltage to 13 .7V to fully charge the battery.

Device Specifications:

• The input voltage is not more than 140 V.
• Work with solar panels for 12 and 24 V.
• The efficiency is almost 100%.
• Ability to work with a variety of batteries of various types.
• The maximum input current reaches 60 A.
• Operating temperature -25 to 55 ºC.
• The ability to charge the battery from scratch.

Thus, PWM controllers are used most often when the load is not very large and solar energy is sufficient. Such devices are more suitable for owners of small country houses where solar panels of low power are installed.

The MPPT controller, as mentioned above, is by far the most popular, because it has a high efficiency and is able to work even in conditions of lack of sunlight. The MPPT controller is also capable of operating at increased power, ideal for a large country house. However, when choosing a particular type, you need to consider the amount of input and output current, as well as the degree of power and voltage indicators.

Installing an MPPT controller in small areas is not practical as it will not pay off. If the total voltage of the solar battery is more than 140 V, then an MPPT controller should be used. PWM controllers are the most affordable, as their price starts from 800 rubles.There are models for 10 thousand, when the cost of an MPPT controller is approximately equal to 25 thousand.

Homemade controller: features, accessories

The device is designed to work with only one solar panel, which creates a current with a force not exceeding 4 A. The capacity of the battery, the charging of which is controlled by the controller, is 3,000 Ah.

For the manufacture of the controller, you need to prepare the following elements:

• 2 chips: LM385-2.5 and TLC271 (is an operational amplifier);
• 3 capacitors: C1 and C2 are low power, have 100n; C3 has a capacity of 1000u, rated for 16V;
• 1 indicator LED (D1);
• 1 Schottky diode;
• 1 diode SB540. Instead, you can use any diode, the main thing is that it can withstand the maximum current of the solar battery;
• 3 transistors: BUZ11 (Q1), BC548 (Q2), BC556 (Q3);
• 10 resistors (R1 - 1k5, R2 - 100, R3 - 68k, R4 and R5 - 10k, R6 - 220k, R7 - 100k, R8 - 92k, R9 - 10k, R10 - 92k). All of them can be 5%. If you want more accuracy, then you can take 1% resistors.

Where and how is solar energy used?

Flexible panels are used in various fields. Before drawing up a project for energy supply at home with these solar panels, find out where they are used and what are the features of their use in our climate.

Scope of solar panels

The use of flexible solar panels is very wide. They are successfully used in electronics, electrification of buildings, automobile and aircraft construction, and space objects.

In construction, such panels are used to provide residential and industrial buildings with electricity.

Portable chargers based on flexible solar cells are available to everyone and are sold everywhere.Large flexible tourist panels for generating electricity anywhere in the world are very popular among travelers.

A very unusual but practical idea is to use the roadbed as the basis for flexible batteries. Special elements are protected from impacts and are not afraid of heavy loads.

This idea has already been implemented. The "solar" road provides energy to the surrounding villages, while not occupying a single extra meter of land.

Features of the use of flexible amorphous panels

Those who plan to start using flexible solar panels as a source of electricity for their home should be aware of the features of their operation.

Solar panels with a flexible metal base are used where increased requirements are imposed on the wear resistance of mini-power plants:

First of all, users are concerned about the question, what to do in winter, when the daylight hours are short and there is not enough electricity for the functioning of all devices?

Yes, in cloudy weather and short daylight hours, the performance of the panels is reduced. It is good when there is an alternative in the form of the possibility of switching to a centralized power supply. If not, you need to stock up on batteries and charge them on days when the weather is favorable.

An interesting feature of solar panels is that when the photocell is heated, its efficiency decreases significantly.

The number of clear days per year varies by region. Of course, in the south it is more rational to use flexible batteries, since the sun shines there longer and more often.

Since during the day the Earth changes its position relative to the Sun, it is better to place the panels universally - that is, on the south side at an angle of about 35-40 degrees. This position will be relevant both in the morning and evening hours, and at noon.

Why should you control the charge and how does the solar charge controller work?

Main reasons:

1. Allows the battery to last longer! Overcharging can cause an explosion.
2. Each battery works with a certain voltage. The controller allows you to select the desired U.

The charge controller also disconnects the battery from consumption devices if it is very low. In addition, it disconnects the battery from the solar cell if it is fully charged.

Thus, insurance occurs and the operation of the system becomes safer.

The principle of operation is extremely simple. The device helps to maintain balance and does not allow the voltage to drop or rise too much.

Types of controllers for solar battery charging

1. Homemade.
2. MRRT.
3. On/Off.
4. hybrids.
5. PWM types.

Below we briefly describe these options for lithium and other batteries.

DIY controllers

When there is experience and skills in radio electronics, this device can be made independently. But it is unlikely that such a device will have high efficiency. A homemade device is most likely suitable if your station has low power.

To build this charge device, you will have to find its circuit. But keep in mind that the error should be 0.1.

Here is a simple diagram.

MPRT

Capable of monitoring the largest recharge power limit. Inside the software is an algorithm that allows you to track the level of voltage and current.It finds a certain balance in which the entire installation will work with maximum efficiency.

The mppt device is considered one of the best and most advanced to date. Unlike PMW, it increases system efficiency by 35%. Such a device is suitable when you have a lot of solar panels.

Instrument type ONOF

It is the simplest one on the market. It doesn't have as many features as the others. The device turns off the battery charging as soon as the voltage rises to the maximum.

Unfortunately, this type of solar charge controller is unable to charge up to 100%. As soon as the current jumps to the maximum, a shutdown occurs. As a result, an incomplete charge reduces its useful life.

hybrids

Applies data to the instrument when there are two types of current source, such as sun and wind. Their construction is based on PWM and MPPT. Its main difference from similar devices is the characteristics of current and voltage.

Its purpose is to equalize the load going to the battery. This is due to the uneven flow of current from the wind generators. Because of this, the life of energy storage devices can be significantly reduced.

PWM or PWM

The operation is based on pulse-width modulation of the current. Allows you to solve the problem of incomplete charging. It lowers the current and thereby brings the recharge to 100%.

As a result of pwm operation, there is no overheating of the battery. As a result, this solar control unit is considered very effective.

Types of solar controllers

In the modern world, there are three types of controllers:

– On-off;

- PWM;

– MPPT controller;

On-Off is the simplest solution for charging, such a controller directly connects the solar panels to the battery when its voltage reaches 14.5 volts. However, this voltage does not indicate that the battery is fully charged. To do this, you need to maintain current for some time so that the battery gains the energy necessary for a full charge. As a result, you get chronic undercharging of batteries and a shortened battery life.

PWM controllers maintain the required voltage to charge the battery by simply "cutting off" the excess. Thus, the device is charged regardless of the voltage supplied by the solar battery. The main condition is that it be higher than necessary for the charge. For 12V batteries, the fully charged voltage is 14.5V, and the discharged voltage is about 11V. This type of controller is simpler than the MPPT, however, has a lower efficiency. They allow you to fill the battery to 100% of its capacity, which gives a significant advantage over systems such as "On-Off".

MPPT controller - has a more complex device that can analyze the operating mode of the solar battery. Its full name sounds like “Maximum power point tracking”, which in Russian means “Maximum power point tracking”. The power that a panel gives out is very dependent on the amount of light that falls on it.

The fact is that the PWM controller does not analyze the state of the panels in any way, but only generates the necessary voltages for charging the battery. MPPT monitors it, as well as the currents produced by the solar panel, and forms the output parameters that are optimal for charging storage batteries.Thus, the current in the input circuit is reduced: from the solar panel to the controller, and energy is used more rationally.

What are the types of controller modules

Before choosing a charge controller, it will not be superfluous to understand the main technical characteristics of the devices. The main difference between popular models of solar charge regulators is the method of bypassing the voltage limit. There are also functional characteristics that directly affect the practicality and ease of use of "smart" electronics. Consider the popular and popular types of controllers for modern solar systems.

1) On/Off controllers

The most primitive and unreliable way to distribute energy resources. Its main drawback is that the storage capacity is charged up to 70–90% of the actual nominal capacity. The primary task of On / Off models is to prevent overheating and overcharging of the battery. The controller for the solar battery blocks recharging when the limit value of the voltage coming "above" is reached. This usually happens at 14.4V.

Such solar controllers use an outdated function to automatically turn off the recharging mode when the maximum indicators of the generated electric current are reached, which does not allow charging the battery by 100%. Because of this, there is a constant shortage of energy resources, which negatively affects the battery life. Therefore, it is not advisable to use such solar controllers when installing expensive solar systems.

2) PWM controllers (PWM)

Pulse-width modulation control circuits do their job much better than On/Off devices. PWM controllers prevent excessive battery overheating in critical situations, increase the ability to accept an electric charge and control the process of energy exchange within the system. The PWM controller additionally performs a number of other useful functions:

• equipped with a special sensor for taking into account the temperature of the electrolyte;
• calculates temperature compensations at various charge voltages;
• supports work with different types of storage tanks for the home (GEL, AGM, liquid acid).

As long as the voltage is below 14.4V, the battery is directly connected to the solar panel, making the charging process very fast. When the indicators exceed the maximum allowable value, the solar controller will automatically lower the voltage to 13.7 V - in this case, the recharging process will not be interrupted and the battery will be charged to 100%. The operating temperature of the device ranges from -25℃ to 55℃.

3) MPPT controller

This type of regulator constantly monitors the current and voltage in the system, the principle of operation is based on the detection of the "maximum power" point. What does it give in practice? Using an MPPT controller is advantageous because it allows you to get rid of excess voltage from the photocells.

These models of regulators use pulse-width conversion in each individual cycle of the battery recharging process, which allows you to increase the output of solar panels. On average, savings are about 10-30%

It is important to remember that the output current from the battery will always be higher than the input current that comes from the photocells.

MPPT technology ensures battery charging even in cloudy weather and insufficient solar radiation. It is more expedient to use such controllers in solar systems with a power of 1000 W and above. The MPPT controller supports operation with non-standard voltages (28 V or other values). The efficiency is kept at the level of 96-98%, which means that almost all solar resources will be converted into direct electric current. The MPPT controller is considered the best and most reliable option for domestic solar systems.

4) Hybrid charge controllers

This is the best option if a combined power supply scheme is used as a power plant for a private house, which consists of a solar plant and a wind generator. Hybrid devices can operate using MPPT or PWM technology, but the current-voltage characteristics will be different.

Wind turbines produce electricity unevenly, which leads to an unstable load on the batteries - they operate in the so-called "stress mode". When a critical load occurs, the hybrid solar controller discharges excess energy using special heating elements that are connected to the system separately.

controller requirements.

If solar panels have to provide energy to a large number of consumers, a home-made hybrid battery charge controller will not be a good option - in terms of reliability, it will still be significantly inferior to industrial equipment. However, for domestic use, a microcircuit can be assembled - its circuit is simple.

It only performs two tasks:

• prevents batteries from being overcharged, which could lead to an explosion;
• eliminates the complete discharge of the batteries, after which it becomes impossible to charge them again.

After reading any review of expensive models, it is easy to make sure that this is exactly what is hidden behind big words and advertising slogans. To give the microcircuit the appropriate functionality on its own is a feasible task; the main thing is the use of high-quality parts so that the hybrid battery charge controller from the panels does not burn out during operation.

The following requirements are imposed on high-quality do-it-yourself equipment:

• it should work according to the formula 1.2P≤UxI, where P is the power of all photocells in total, I is the output current, and U is the voltage in the network with empty batteries;
• the maximum U at the input must be equal to the total voltage in all batteries in idle time.

When assembling the device with your own hands, you need to read the review of the option found and make sure that its circuit meets these parameters.

Assembly of a simple controller.

While a hybrid charge controller allows you to connect multiple voltage sources, a simple one is suitable for systems that include only solar panels. It can be used to power networks with a small number of energy consumers. Its circuit consists of standard electrical elements: keys, capacitors, resistors, a transistor and a comparator for adjustment.

The principle of operation of the device is simple: it detects the level of charge of the connected batteries and stops recharging when the voltage reaches its maximum value. When it falls, the charging process resumes.The current consumption stops when U reaches the minimum value (11 V) - this does not allow the cells to be completely discharged when there is not enough solar energy.

The characteristics of such solar panel equipment are as follows:

• standard input current U - 13.8 V, can be adjusted;
• battery disconnection occurs when U is less than 11 V;
• charging resumes at a battery voltage of 12.5 V;
• comparator TLC 339 is used;
• at a current of 0.5 A, the voltage drops by no more than 20 mV.

Hybrid version with your own hands.

An advanced hybrid solar controller allows you to use energy around the clock - when there is no sun, direct current is supplied from a wind generator. The device circuit includes trimmers that are used to adjust parameters. Switching is carried out using a relay, which is controlled by transistor keys.

Otherwise, the hybrid version does not differ from the simple one. The circuit has the same parameters, the principle of its operation is similar. You will have to use more parts, so it is more difficult to assemble it; for each element used, it is worth reading the review to make sure of its quality.

When you need a controller

So far, solar energy has been limited (at the household level) to the creation of photovoltaic panels of relatively low power. But regardless of the design of the photoelectric converter of sun light into current, this device is equipped with a module called a solar battery charge controller.

Indeed, the installation scheme for photosynthesis of sunlight includes a rechargeable battery - a storage device for energy received from a solar panel.It is this secondary energy source that is served primarily by the controller.

Next, we will understand the device and the principles of operation of this device, as well as talk about how to connect it.

The need for this device can be reduced to the following points:

1. Battery charging is multi-stage;
2. Adjusting the on / off battery when charging / discharging the device;
3. Connecting the battery at maximum charge;
4. Connecting charging from photocells in automatic mode.

The battery charge controller for solar devices is important because the performance of all its functions in good condition greatly increases the life of the built-in battery.

Peculiarities

Charge controllers have several important features. The most important are the protection functions that serve to increase the reliability of this device.

It should be noted the most common types of protection in such structures:

devices are equipped with reliable protection against incorrect polarity connection;
it is very important to prevent the possibility of short circuits in the load and at the input, so manufacturers provide controllers with reliable protection against such situations;
important is the protection of the device from lightning, as well as various overheating;
controller designs are equipped with special protection against overvoltage and battery discharge at night.

Additionally, the device is equipped with a variety of electronic fuses and special information displays. The monitor allows you to find out the necessary information about the state of the battery and the entire system.

In addition, a lot of other important information is displayed on the screen: battery voltage, charge level and much more. The design of many models of controllers includes special timers, due to which the night mode of the device is activated. The design of many models of controllers includes special timers, due to which the night mode of the device is activated.

The design of many models of controllers includes special timers, due to which the night mode of the device is activated.

In addition, there are more complex models of such devices that can simultaneously control the operation of two independent batteries. In the name of such devices there is a prefix Duo.