MPPT Solar Charge Controller using LT3652 (2022)

Almost every Solar based system has a Battery associated with it which has to be charged from solar energy and then the energy from the battery will be used to drive the loads. There are multiple choices available for charging a lithium battery, we have also built a simpleLithium battery charging circuit previously. But to charge a battery with a solar panel, the most popular choice is the MPPT or maximum power point tracker topology because it provides much better accuracy than other methods like PWM controlled chargers.

MPPT is an algorithm commonly used in solar chargers. The charge controller measures the output voltage from the panels and the battery voltage, then by getting these two data, it compares them to decide the best power that the panel could provide to charge the battery. At whatever the situation, whether in good or poor sunlight condition, the MPPT charge controller uses this maximum power output factor and converts this to the best charge voltage and current for the battery. Whenever the power output from the solar panel gets dropped, the battery charge current also decreases.

Thus, in poor sunlight conditions, the battery continuously gets charged according to the output of the solar panel. This is usually not the case in normal solar chargers. Because each solar panels comes with a maximum output current rating and a short circuit current rating. Whenever the solar panel could not provide the proper current output, the voltage falls significantly and the load current does not change and crosses the short circuit current rating making the output voltage of the solar panel is zero. Hence, the charging gets stopped completely in poor sunlight conditions. But MPPT allows the battery to charge even in the poor sunlight condition by controlling the battery charge current.

MPPTs are around 90-95% efficient in the conversion. However, efficiency is also dependable on the solar driver temperature, battery temperature, solar panel quality, and conversion efficiency. In this project, we will build a Solar MPPT charger for lithium batteries and check the output. You can also check out the IoT Based Solar battery monitoring Project in which we monitoring some critical battery parameters of a lithium battery installed in a Solar System.

MPPT Charge Controller - Design Considerations

The MPPT Charge controller circuit that we design in this project will have the following specifications meat.

  1. It will charge a 2P2S battery (6.4-8.4V)
  2. Charge current will be 600mA
  3. It will have an additional charging option using an adapter.

Components Required for Building MPPT Controller

  1. LT3652 Driver
  2. 1N5819 - 3 pcs
  3. 10k pot
  4. 10uF Capacitors - 2 pcs
  5. Green LED
  6. Orange LED
  7. 220k resistor
  8. 330k resistor
  9. 200k resistor
  10. 68uH Inductor
  11. 1uF capacitor
  12. 100uF capacitor - 2 pcs
  13. Battery - 7.4V
  14. 1k resistors 2 pcs
  15. Barrel socket

MPPT Solar Charger Circuit Diagram

The complete Solar Charge Controller Circuit can be found in the image below. You can click on it for a full-page view to get better visibility.

(Video) How to Build a MPPT Solar Charge Controller to Effectively Charge Lithium Battery using Solar Panel

The circuit uses LT3652 which is a complete monolithic step-down battery charger that operates over a 4.95V to 32V input voltage range. Thus, the maximum input range is 4.95V to the 32V for both solar and adapter. The LT3652 provides a constant current / constant voltage charge characteristics. It can be programmed through current sense resistors for a maximum of 2A charge current.

On the output section, the charger employs 3.3V float voltage feedback reference, so any desired battery float voltage up to 14.4V can be programmed with a resistor divider. The LT3652 also contains a programmable safety timer using a simple capacitor. It is used for charge termination after the desired time is reached. It is useful to detect battery faults.

The LT3652 requires MPPT setup where a potentiometer can be used to set the MPPT point. When the LT3652 is powered using a solar panel, the input regulation loop is used to maintain the panel at peak output power. From where the regulation is maintained depends on the MPPT setup potentiometer.

All these things are connected to the schematic. The VR1 is used to set the MPPT point. R2, R3, and R4 are used to set the 2S battery charging voltage (8.4V). Formula to set battery voltage can be given by-

RFB1 = (VBAT(FLT) • 2.5 • 105)/3.3 and RFB2 = (RFB1 • (2.5 • 105))/(RFB1 - (2.5 • 105))

The capacitor C2 is used to set up the charge timer. The timer can be set using the below formula-

 tEOC = CTIMER • 4.4 • 106 (In Hours)

The D3 and C3 are the boost diode and boost capacitor. It drives the internal switch and facilitates the saturation of the switch transistor. The boost pin operates from 0V to 8.5V.

R5 and R6 are a current sense resistor connected in parallel. The charge current can be calculated using the below formula-

(Video) Solar Battery Charger (LiPo/Li-Ion) || DIY or Buy

RSENSE = 0.1/ ICHG(MAX)

The current sense resistor in the schematic is selected 0.5 Ohms and 0.22 Ohms which is in parallel creates 0.15 Ohms. Using the above formula, it will produce almost 0.66A of charge current. The C4, C5, and C6 are the output filter capacitors.

The DC barrel jack is connected in such a way that the solar panel will get disconnected if an adapter jack is inserted into the adapter socket. The D1 will protect the solar panel or the adapter from reverse current flow during no charging condition.

Solar Charge Controller PCB Design

For the above discussed MMPT circuit, we designed the MPPT charger controller circuit board that is shown below.

MPPT Solar Charge Controller using LT3652 (2)

The design has the necessary GND copper plane as well as proper connecting vias. However, the LT3652 requires adequate PCB heat sink. This is created using the GND copper plane and placing vias in that solder plane.

Ordering the PCB

Now we understand how the schematics work, we can proceed with building the PCB for ourMPPT Solar Charger Project. The PCB layout for the above circuit is also available for download as Gerber from the link.

  • Download GERBER for MPPT Solar Charger

Now our design is ready, it is time to get them fabricated using the Gerber file. To get thePCB done from PCBGOGO is quite easy, simply follow the steps below-

(Video) Electronics: MPPT (LT3652) + Solar Panel Voltage

Step 1:Get intowww.pcbgogo.com, sign up if this is your first time. Then in the PCB Prototype tab, enter the dimensions of your PCB, the number of layers, and the number of PCB you require. Assuming the PCB is 80cm×80cm, you can set the dimensions as shown below.

MPPT Solar Charge Controller using LT3652 (3)

Step 2:Proceed by clicking on theQuote Nowbutton. You will be taken to a page where to set a few additional parameters if required like the material used track spacing, etc. But mostly, the default values will work fine. The only thing that we have to consider here is the price and time. As you can see the Build Time is only 2-3 days and it just costs only $5 for our PCB. You can then select a preferred shipping method based on your requirement.

MPPT Solar Charge Controller using LT3652 (4)

Step 3:The final step is to upload theGerber fileand proceed with the payment. To make sure the process is smooth, PCBGOGOverifies if your Gerber file is valid before proceeding with the payment. This way, you can sure that your PCB is fabrication friendly and will reach you as committed.

Assembling the PCB

After the board was ordered, it reached me after some days through courier in a neatly labeled well-packed box, and like always, the quality of the PCB was awesome. The PCB that was received by me is shown below. As you see, both the top and bottom layer has turned out as expected.

MPPT Solar Charge Controller using LT3652 (5)

(Video) Solar Controller Battery Charger: How It's Made ( LT3652 )

The vias and pads were all in the right size. It took me around 15 minutes to assemble to PCB board to get a working circuit. The assembled board is shown below.

MPPT Solar Charge Controller using LT3652 (6)

Testing our MPPT Solar Charger

To test the circuit, a solar panel with 18V .56A of rating is used. The below image is the detailed specification of the solar panel.

MPPT Solar Charge Controller using LT3652 (7)

A 2P2S battery (8.4V 4000mAH) battery is used for charging.The complete circuit is tested in moderate sun condition–

MPPT Solar Charge Controller using LT3652 (8)

After connecting everything, the MPPT is set when the Sun condition is proper and the potentiometer is controlled until the charge LED starts to glow. The circuit worked pretty well and the detailed working, setup, and explanation can be found in the video linked below.

(Video) Electronics: MPPT Sunny Buddy (LT3652) + Solar Panel Voltage

Hope you enjoyed the project and learned something useful. If you have any questions, please leave them in the comment section below. You can also use our forums to get your other technical queries answered.

FAQs

How many watts can a 30 amp MPPT solar controller handle? ›

The 30-amp solar charge controller has a maximum input of 450 Watts from a solar array. The 30-amp solar charge controller is designed for a 12-volt system only. 12-volt nominal output solar panels should be connected in parallel to keep the voltage at 12 volts.

Can I use MPPT controller with lithium battery? ›

Uses Maximum Power Point Tracking (MPPT) for maximum efficiency and charge rate. Able to charge lead acid (sealed, gel or flooded) or lithium battery banks between 8V to 32V, and supports 12V solar arrays up to 260W or 24VDC arrays up to 520W.

How many amp should my MPPT charge controller handle? ›

You take the total watts of the solar array divided by the voltage of the battery bank. That will give you the output current of the charge controller. For example, a 1000W solar array ÷ 24V battery bank = 41.6A. The rating of the charge controller should be at least 40A.

Can you mix PWM with MPPT? ›

Mixing MPPT and PWM charge controllers to the same battery isn't a problem.

How many 100 watt solar panel do I need for a 30 amp controller? ›

By the rule of thumb, a 100 watt solar panel inputs 30 amp-hours per day into your batteries. So you would need 1.33 100 watt panels, or one 133 watt panel to match your solar power needs.

How many watts can a 60 amp MPPT charge controller handle? ›

How many watts can a 60 amp charge controller handle. In theory, a 60 amp charge controller can handle as high as 3400W solar panels input when the battery bank is 48V.

Do I need a special solar controller for lithium battery? ›

A lithium ion solar charge controller is required similarly for LifePO4 Battery and lithium-ion batteries. There are various types of batteries available in the market with the technological advancement for high efficiency and options available in chemistry to do so.

Can I connect MPPT charge controller to inverter? ›

MPPT charge controllers help to flow the current efficiently into a depleted battery. If we connect an MPPT charge controller directly to the inverter, your system can get damaged, but if not damaged, there will be zero input in the inverter. So connecting MPPTs directly to the inverter is a bad idea!

Can I charge lithium battery with solar charge controller? ›

If you use a charge controller, then any type of solar panel can charge a lithium-ion battery. You will need certain components to charge a battery with a solar panel. These include a charge controller, solar panels, and a rechargeable battery.

What happens if your charge controller is too big? ›

MPPT Charge Controllers

There is a practical limit though, if the solar array is too large then the power is just wasted, since the charge controller is always limiting the output. A typical recommendation is to limit the solar array to 110%-125% of the maximum controller rating.

What size of charge controller do I need for 200Ah battery? ›

You need around 610 watts of solar panels to charge a 12V 200Ah lithium battery from 100% depth of discharge in 5 peak sun hours with an MPPT charge controller. You need around 760 watts of solar panels to charge a 12V 200Ah lithium battery from 100% depth of discharge in 5 peak sun hours with a PWM charge controller.

What size charger do I need for a 200Ah battery? ›

For Lithium and Lead Crystal batteries, the charger to battery ratio is based on 30% for maximum performance and lifespan. That means a 200Ah requires a 60Amp charger.

Why MPPT is better than PWM? ›

The main difference between PWM and MPPT charge control devices is that the MPPT devices are more efficient. MPPT charge control devices have 30 % more efficient in charge efficiency according to PWM type. Panel voltage and battery voltage should be matched in PWM systems.

Can I use 2 solar charge controllers? ›

To meet high power charging requirements, several solar controllers can be connected in parallel to a battery bank with each controller connected to its own separate PV subarray. For MPPT controllers, MPPT tracking of each subarray is preferred, as there is less impact with voltage mismatches.

What is best PWM or MPPT? ›

A PWM controller operates at a relatively constant harvesting efficiency regardless of the size of the array. A PWM controller is less expensive that a MPPT, so is a more economical choice for a small system. A MPPT controller is much less efficient in low power applications.

How do I choose a MPPT charge controller? ›

In order to check if the charge controller works for your system, divide the total wattage of your solar array by the voltage of your battery bank. For example, a 2000W solar array ÷ 36V battery bank = 55.6A. The rating of the charge controller should be at least 55.6A.

How many watts can a 20 amp MPPT charge controller handle? ›

How many watts can Renogy Rover 20 amp charge controller handle? The Rover MPPT charge controller can work with standard off-grid 12/24V solar panels with high voltage or multiple panels with voltage up to 100V. And the maximum combined input solar power is 260W for a 12V battery system or 520W for a 24V system.

How many 100w solar panels does it take to power a house? ›

An average single-family home typically installs around 20 panels.

How many watts can a 50 amp MPPT charge controller handle? ›

Note: Assuming you are using a 12V battery and 2 x 300W panels, the MPPT charger controller output current will be roughly: 600W / 12V = 50A max. So you should use a 50A MPPT solar charge controller.

How many watts can a 40A MPPT charge controller handle? ›

How many watts can Renogy Rover 40 amp charge controller handle? The Rover MPPT charge controller can work with standard off-grid 12/24V solar panels with high voltage or multiple panels with voltage up to 100V. And the maximum combined input solar power is 520W for a 12V battery system or 1040W for a 24V system.

What size charge controller do I need for 1000 watts? ›

to calculate that. use this formula: 1000W/24V= 42 Amp, So you will need a 24V 40A Solar Charge Controller for the 1000W Solar Panel at least. 1000W/48V= 22 Amps, add 25% safety margin, if the battery system is 48V, and 30A 48V Solar Charge Controller is a good option for 1000W Solar Panels.

What size solar panel do I need to charge a 100Ah lithium battery? ›

You need a 5-10 watt solar panel to maintain a 100Ah lithium battery.

What size solar panel do I need to charge 120Ah lithium battery? ›

Leisure-style deep-cycle battery: (120Ah x 50%) = 60 x 12 volts = 720 watts-hours. This battery will need 2 x 100 watt solar panels to recharge in one day ( 2 x 100 solar watts = 800 Wh/day on average.).

Can I connect solar panel directly to lithium battery? ›

A solar panel can be connected directly to a 12 volt car battery, but must be monitored if it's more than 5 watts. Solar panels rated higher than 5 watts must not be connected directly to a battery, but only through a solar charge controller to protect against over-charging.

Can I connect solar panel and inverter to the same battery? ›

You can connect all solar panel inverters for home to the same battery bank or each inverter to its battery bank. The next thing I show is that each solar panel to inverters can link to its battery.

Can I charge a battery while it's connected to an inverter? ›

The battery will need to be recharged as the power is drawn out of it by the inverter. The battery can be recharged by running the automobile motor, or a gas generator, solar panels, or wind. Or you can use a battery charger plugged into an AC outlet to recharge the battery.
...
Frequently Asked Questions about Power Inverters.
Computer:300 Watts
Total Needed:430 Watts
2 more rows

Can MPPT charge LiFePO4? ›

Powerwerx MPPT-150-14.6 is a MPPT (maximum power point tracking) controller is a DC to DC solar converter. This unit is rated at 150 watts and converts higher solar panel voltages down to 14.6 VDC which is more suitable for charging LifePO4 type batteries. The solar input is pre-wired with MC4 style connectors.

How long does it take to charge a 100Ah lithium battery? ›

The low resistance in the Lithium cells allow the battery to accept the full output from the charger. With a 30 Amp charger, a 100Ah Lithium battery can be fully charged from flat to full in just over 3 hours vs. 10+ for a 100Ah AGM battery.

Can I use PWM solar charge controller for lithium battery? ›

Never ever connect lithium batteries to PWM chargers ! PWM gives out a pulsating power. That destroys a lithium battery.

How many watts can a 40 amp MPPT charge controller handle? ›

5. How many watts can Renogy Rover 40 amp charge controller handle? The Rover MPPT charge controller can work with standard off-grid 12/24V solar panels with high voltage or multiple panels with voltage up to 100V. And the maximum combined input solar power is 520W for a 12V battery system or 1040W for a 24V system.

How many watts can 30 amp handle? ›

The formula is 30 amps X 120 volts = 3,600 watts.

How many watts can a 50 amp MPPT charge controller handle? ›

Note: Assuming you are using a 12V battery and 2 x 300W panels, the MPPT charger controller output current will be roughly: 600W / 12V = 50A max. So you should use a 50A MPPT solar charge controller.

What size charge controller do I need for 1200 watts? ›

How to calculate charge controller size for a solar panel?
Solar panel powerSolar panel voltageRecommended charge controller size
300 watts12 volts30 amps
400 watts40 volts12 amps
1000 watts24 volts50 amps
1200 watts20 volts72 amps
2 more rows
May 1, 2022

How do I match my solar panels to MPPT? ›

First look at the datasheets of the solar panels to see what their maximum open circuit voltage is. Then multiply that by the number of panels that are in series in the array. The result of the multiplication must not be higher than the Maximum PV open circuit voltage as listed on the MPPT Datasheet.

How many amps is 500 watts solar? ›

In conclusion, a 40V 500W solar panel can produce 65.625 amps with 5 hours of sunlight. This is enough to fully charge an empty 60 Ampere-hour or a 2,500 watt-hour battery hooked to your solar inverter.

What size charge controller do I need for a 500 watt solar panel? ›

For a 500 watt solar panel set up, a 30 AMP charge controller should be large enough to handle most solar power systems operating at peak capacity.

How many amps is 3000 watts? ›

For example, 3000 Watt equals to: 25 Amps, if you use 120 V. 13.64 Amps, if you use 220 V.

How many amps is 240 volts? ›

Amps = Watts / Volts

3600 Watts / 240 Volts = 15 Amps.

How many amps is 220 volts? ›

In 220 volt it 5 amp .

Can MPPT overcharge battery? ›

Using maximum power point tracking (MPPT) technology, the hybrid inverter optimizes solar production. The hybrid inverter also controls the battery charging voltage and prevents overcharging.

Can I connect MPPT charge controller to inverter? ›

MPPT charge controllers help to flow the current efficiently into a depleted battery. If we connect an MPPT charge controller directly to the inverter, your system can get damaged, but if not damaged, there will be zero input in the inverter. So connecting MPPTs directly to the inverter is a bad idea!

What size charge controller do I need for 1000 watts? ›

to calculate that. use this formula: 1000W/24V= 42 Amp, So you will need a 24V 40A Solar Charge Controller for the 1000W Solar Panel at least. 1000W/48V= 22 Amps, add 25% safety margin, if the battery system is 48V, and 30A 48V Solar Charge Controller is a good option for 1000W Solar Panels.

What happens if your charge controller is too big? ›

MPPT Charge Controllers

There is a practical limit though, if the solar array is too large then the power is just wasted, since the charge controller is always limiting the output. A typical recommendation is to limit the solar array to 110%-125% of the maximum controller rating.

How many solar panels do I need for a 200Ah battery? ›

Summary. You need around 610 watts of solar panels to charge a 12V 200Ah lithium battery from 100% depth of discharge in 5 peak sun hours with an MPPT charge controller.

How many watts can a 20 amp MPPT charge controller handle? ›

How many watts can Renogy Rover 20 amp charge controller handle? The Rover MPPT charge controller can work with standard off-grid 12/24V solar panels with high voltage or multiple panels with voltage up to 100V. And the maximum combined input solar power is 260W for a 12V battery system or 520W for a 24V system.

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