MPPT Charge Controller

MPPT Charge Controller Intro

MPPT Charge controller is a technology that is specifically made to work with virtually all the photovoltaic. Certainly, it’s for the solar unit wherein module voltages are higher than the battery voltages. It’s an electronic system that assists the solar module produces all the power which they are able to. On the other hand, it’s not the mechanical tracking technology which physically moves the modules towards the direction of the sun to convert more solar energy to electrical energy.

At MPPT solar charge controller is a smart electronic device which looks at the power output of the solar array which is feeding power into the charge controller and looks at the battery collection which is needing charging and matched the voltage and current to utilize the utmost output of the solar array.

What is mppt charge controller

The MPPT charge controller refers to the “Maximum Power Point Tracking” solar charge controller, which is an up gradation of the traditional solar panel charge controller. The MPPT solar charge controller detects the solar panel voltage and current in real time and constantly tracks for maximum power (P=U*I) so that the system always charges the battery with maximum power.

mppt charge controller
mppt charge controller simple guide

What is Maximum Power Point Tracking

The Maximum Power Point Tracking (MPPT) system is an electronic system that enables the photovoltaic panel to output more power by adjusting the working state of the electrical module. The DC power generated by the solar panel can be efficiently stored in a battery. It can cater to the residential and industrial electricity consumption in remote areas and tourist areas which are not connected to conventional power grids. Generating and consuming energy from a solar photovoltaic system is environmentally friendly.

The MPPT charge controller detects the solar panel’s generated power in real time and tracks the highest voltage and current value (VI), hence charging the battery with maximum power output. It is the brain of the photovoltaic system used to coordinate the work of solar panels, batteries and loads.

Maximum Power Point TrackingMaximum Power Point Tracking
Maximum Power Point Tracking

Since the solar collection by panels is affected by the sunlight and factors like dust, pollution, rain, snow, and shade, etc. the output power changes accordingly. When the sunlight is strong and bright, the power converted by solar panels is at its peak.

The MPPT Solar Charge controller is designed to make full use of the solar array to keep it stay in the peak conversion. In case of same sunlight or insolation level, the output power by an MPPT Solar Controller is higher than a PWM Charge Controller.

How MPPT Charge Controller Works

The MPPT control is generally completed by a DC/DC converter circuit. The photovoltaic cell array is connected to the load through a DC/DC circuit and the maximum power tracking device continuously detects the current-voltage variation of the photovoltaic array. It automatically adjusts the PWM drive signal duty cycle of DC/DC Converter according to the variation.

For linear circuits, when the load resistance is equal to the internal resistance of the power supply, the power supply has the maximum power output. The photovoltaic cells and DC/DC converter circuits are strong in nonlinearity. However, for a very short time, it can be considered as a linear circuit. As long as the equivalent resistance of the DC-DC converter circuit is adjusted so that it is always equal to the internal resistance of the photovoltaic cell, the maximum output of the photovoltaic cell can be realized and the maximum power point of the photovoltaic array is realized.

How to Size MPPT Solar Charge Controller

With the rapid technological advancements, there are various types of MPPT solar charge controllers. When choosing the right MPPT solar controller, we have to pay attention to 2 aspects: the current of the solar panel and the voltage of the solar panel.

Solar Panels Voltage

As per the Solar panels, we need to pay attention to the working voltage and short-circuit voltage. Working voltages normally are 18V, 36V and so on. If the working voltage is 18V, the short-circuit voltage of the solar panel should be 22V, similarly if 36V the short-circuit voltage should be 42V. you need to choose the right controller according to the working voltage of the solar panels. Usually, when you buy the solar panels, you will have all the parameters correspondingly.

Solar Panels Current

The size of the solar controller is often in the name of how much current the solar controller handles (that is, the maximum charging current). In the market, generally, a solar controller will have 10A, 20A or 30A sizes. Some high power controllers can also handle 50A, 60A current. Even greater, 80A Solar Controller and 100A Solar Controller are also common.

When selecting the controller, please note that the discharge current of the solar panel cannot exceed this value otherwise the controller will be damaged. So, when choosing a controller, we recommend that if the solar panel current is 6A, we should choose a 10A charge controller.

The Solar panels input voltage of the MPPT solar controller is generally about 0~150V, and the input voltage of the PWM solar controller is generally 0~55V. As long as the voltage is under these values, the right MPPT controller is easy to find. In case of special requirements, if these input voltages are higher than the rated values, it’s also easy to find a solar charge controller manufacturer to order one.

What is the best mppt charge controller

The best MPPT solar controller is the one which is most suitable for your solar system and fits the requirement of your batteries or storage. You need to know all the details of your PV system, such as the input and output power, maximum battery current, nominal system voltage (12V, 24V, 36V, 48V, 60V, 100V, 150V and 200V, etc). When considering which MPPT controller to choose, refer to the MPPT controller calculation guide above.

MPPT Charge Controller vs PWM: Advantages

In order to charge the battery, the output voltage of the solar panel must be higher than the input voltage of the battery. If the solar panel output voltage is lower than the input voltage of the battery, the output current will be close to zero. Moreover, the output of the solar panel is not fixed but varies with various conditions such as radiation intensity, ambient temperature, etc. It also depends whether the solar panel can work at the maximum value of the IV curve or not, based on the designer’s level and ability.

The operating parameters of the traditional solar charging controller are set unchanged. The parameter mode (constant voltage or constant current) is used as the base to transfer the solar panel energy to the battery and won’t change with the changes in the surrounding environment. The natural environment components like sun’s radiation level, surrounding temperature and humidity are constantly changing. Therefore the energy from the solar panels generated and converted in a fixed manner will charge the battery inadequately. On the other hand, when the weather is good and has good sunlight, solar power cannot be fully utilized and is wasted.

We know that in an independent photovoltaic solar system, the cost of solar panels and batteries accounts for 80%-90% of the total system budget and the controller only accounts for 5%-10%. If the design is reasonable, 5% budget solar controller can optimize the system to its best performance.

Practically, you can see the benefits of the MPPT controller more clearly: in a system that uses a conventional PWM charge controller with a 1000W solar panel capacity and it is replaced by an MPPT controller for the same load, the same battery, you only need to install 700W solar panels and it’s enough to meet the power demand of all electrical equipment. According to the current market price of solar panels at $2/W, the cost of solar panels in the system can be directly reduced to $650. In such cases, in larger systems, the savings can be greater, including the cost of purchasing the panels, cables, and more.

In addition, there are many amorphous silicon solar panels in the market. One trait of this type of panel is that the open circuit voltage is high and the current is small. In practical applications, the traditional PWM controller, including the constant current controller can convert the panel energy with low efficiency, which will cause inadequate charging of the battery thus shortens the service life of batteries. Also, this is the cause of solar energy waste generated by the system. The maximum power point tracking controller can offset the defects in these practical applications, thereby improving overall system performance.

The difference between MPPT solar controller and PMW controller

The main difference between the MPPT controller and PWM controller is in three aspects.

Charge Method Difference

The charging method is different as the PWM charge controller charges in a three-stage charging mode. MPPT is the maximum power tracking technology and the relative charging efficiency can be increased to about 30%.

Charge Voltage Difference

When using an MPPT solar controller to charge a low-voltage battery by a high-voltage solar panel, the charge efficiency will have a big difference with the PWM charge controller under the same condition. If the voltage of the solar panels and the battery are same, for example, both are 12V, then the difference between the practical PWM and the MPPT controller won’t be much.

Solar Power Difference

If the power generated by the solar panel is small, it is better to install a PWM charge controller. If the power generated off the solar panel is large, the MPPT solar controller is a better choice. Usually, the MPPT solar charge controller is expensive than a PWM controller. If the power of the solar panel is small, it is a little waste money to install the MPPT controller.

Features of MPPT Charge Controller

MPPT solar charge controller is usually used in the off-grid solar power generation systems. The energy generated from solar panels is a very valuable resource as it is a clean energy type. If using a traditional PWM controller, the disadvantage is of low conversion rate and a lot of solar energy is wasted. If using an MPPT charge controller instead, the solar conversion rate can be increased a lot with minimal energy wastage. The MPPT solar controller is obviously a better choice when the budget is rich.

Highlights of MPPT Charge Controller

1. High energy conversion efficiency, up to 99%

2. Support all types of solar panels, such as monocrystalline silicon panels, polycrystalline silicon panels, amorphous silicon panels, etc;

3. Rich load working mode: such as time control, pure light control, light control + time control, manual, debug mode, long open mode.

4. Good circuit protection functions, including PV reverse connection protection, PV over-current protection, battery reverse connection protection, battery over-voltage protection, battery over-discharge protection, load over-current protection, load short-circuit protection, etc.

5. Support serial communication functions (Wi-Fi, Bluetooth Control and Monitor Devices)

6. Can support various types of batteries, such as lead-acid batteries, lithium iron phosphate batteries, etc.

7. Support variety of battery voltages, such as 12V, 24V, 36V, 48V, 110V and so on.

3 Stage Charging Mode of MPPT Charge Controller

MPPT Limiting Charge

When the initial charge stage starts, the system detects the battery voltage drop in low value can be charged. The MPPT charge starts working to convert and transfer the PV output power to the battery. When the sunlight is strong, the output power of the PV array will be greatly increased and the charge current hit the threshold value. This is when the MPPT charge stops and turns into constant charge mode. When the sunlight decreases, the constant charge turns into the MPPT charge.

Through this switching method, the battery will be fully charged and the voltage will increase to the saturation voltage (Ur) and the battery turns into the constant charge stage. As the charge mode auto-switches between the MPPT charge and constant charge, the solar energy can be fully utilized to charge the battery in a quick and efficient way.

Constant Voltage Limiting Charge

At this stage, the charging voltage value is always saturated (Ur) and the charging current gradually decreases with the electrochemical reaction in the battery. When the charging current drops to about 0.01 C, the constant voltage charging is terminated and the floating charging phase is entered. The charge current also limits to protect the battery at this stage.

Floating Charge

The charge voltage (Uf) in the floating charge mode is a little lower than the constant charge. The main purpose of this charging mode is to compensate for the self-losing energy of the battery as at this stage, the battery is completely charged.

Benefits of MPPT Solar Charge Controller

When MPPT charge controller is used, the charging efficiency can be improved by 30% i.e. from the same solar panels output, the MPPT charge controller can generate charging current of 1.3 times than before and the battery can be charged faster.

The working principle of the MPPT charge controller: The MPPT charge controller tracks the maximum power point in the solar panel in real time and the solar panel outputs maximum efficiency. The higher the voltage, the more power can be output through the maximum power tracking, thus improving the charging efficiency.

In theory, the use of the MPPT charge controller in the solar power system will increase efficiency by 50% than the traditional ways. But according to zhcsolar testing, due to environmental factors affecting and energy losses, the final efficiency can be increased by 20% – 30%.

The Importance of MPPT Solar Charge Controller

  • When you look at many solar panels in the market and see their results, you’ll see that the range of voltages from low to high with variation under normal operating parameters. A usual solar panel is made to work in excess of 18 volts and storage batteries are made to a range of predefined voltage that is based on the structure of the battery and a lot is made to work at 12 volts.
  • It checks out the work or functions of a standard PV regulator. It tracks the battery charging and at the same time provides them the security from getting undercharged or overcharged. If you connect the regulator straight to the battery and then to the solar module, a high-quality MPPT solar charge controller works out and analyzes the voltage at which the module could generate utmost power as for its capability. Effectiveness and efficiency of most of the MPPT solar charge controllers are between 93% and 96%. This kind of solar charge controller is valuable in cold weather and on cloudy days when there’s almost no sunshine. This is the time when more power is needed to charge the battery in order to keep the SOC level
  • An MPPT solar charge controller could be a remarkable combination with a grid-tied solar module. Another remarkable benefit of the MPPT solar charge controller is that you save lots of time in the cable and wiring expenses that means where a smaller gauge cabling or wiring could be utilized.
  • While selecting an MPPT solar charge controller, you have to ensure that these essential features are on hand: Voltage and Current Regulation, Pulse Width Modulation or PWM control, current compensation & load disconnection, temperature compensation as well as automatic load reconnection.
  • Electronic Security: Overcharging security, deep-discharging security and reverse polarity protection from the module side as well as from the side of the battery. Reverse polarity security from the internal fuse, short circuit security as well as overvoltage security at module input. Also, you need to ensure that there’s open circuit security without battery, over temperature as well as overload security and even battery overvoltage shutdown.

MPPT Charge Controller Circuit Diagram

MPPT Charge Controller Circuit Diagram
MPPT Charge Controller Circuit Diagram

MPPT Solar Charge Controller Negative Ground vs Postive Ground

In simple words, all vehicles have a NEGATIVE ground system, so when choosing MPPT Solar Charge Controller for RV and Autos, remember to choose the Negative Grounding Charge Controller. Here I will explain as to why?

As all vehicles use the battery as the storage of electric energy, all the input and output of electric energy must pass through the battery. Since the battery is direct current (DC), the positive and negative poles become equally important. This is the basic principle of negative ground.

On the vehicle external works, the body of the vehicle is designed to use as the circuit of the negative pole. This means that the vehicle’s steel frame or chassis is directly connected to the negative side of the battery via the negative battery cable.

MPPT Charge Controller Price

The price of the MPPT solar charge controller is usually 3-5 times then the PWM controller which in the same size (amp). Generally, the price difference of the small amp is not as much as the big amps. The price difference between MPPT controller and PWM controller jumps after from 30 amps size. MPPT charge controller price ranges from $70 to $1000 and is common in the market.

An MPPT unit over $1000 is not unusual especially when it is a big unit. According to Comparison Shopping Engine – PriceGrabber, the most expensive 60A MPPT Solar Charge Controller is priced at $1,000.68 by MidNite Solar Classic Lite 60A controller.

In the long run, the MPPT charge controller has a higher return on investment, not matter for the home off-grid system or for commercial purposes. We strongly recommend taking an MPPT controller for your power system.

Best MPPT Solar Charge Controller on the Market

ZHCSolar MPPT Charge Controller Comparison

ZHCSolar MPPT Solar Charge Controller has 30 Amp, 40A, 50 Amp, 60 Amp, 80 Amp, 100 Amp Version for Off-Grid Solar Panel System. The table shows the comparison parameter of the battery voltage, rated charge current, nominal PV power, maximum PV short circuit current and maximum PV open circuit voltage for references.

Victron MPPT Charge Controller Comparison

We have arranged the different Victron MPPT solar charge controllers in a table below to allow easy selection of the right charge controller for your needs. The table shows the comparison parameter of battery voltage, rated charge current, nominal PV power, maximum PV short circuit current and maximum PV open circuit voltage for references.

Victron mppt Charge Controller
Victron mppt Charge Controller
Victron mppt Charge Controller 2
Victron mppt Charge Controller 2

Renogy mppt charge Controller Comparison

Renogy mppt charge Controller Comparison
Renogy mppt charge Controller Comparison
Renogy mppt charge Controller Comparison 2
Renogy mppt charge Controller Comparison 2

Conclusion

In general, the MPPT charge controller tracks the maximum power point in the solar panel in real time to maximize the effectiveness of the solar panel. The higher the voltage, the more power can be output through the maximum power tracking, thus improving the charging efficiency. In this sense, the MPPT solar charge and discharge controller is going to eventually replace the traditional PWM solar controller.