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Connect Solar Panel to Charge Controller: 3 Steps (w/ Videos). Solar control unit

Connect Solar Panel to Charge Controller: 3 Steps (w/ Videos). Solar control unit

    Connect Solar Panel to Charge Controller: 3 Steps (w/ Videos)

    Just so you know, this page contains affiliate links. If you make a purchase after clicking on one, at no extra cost to you I may earn a small commission.

    In this guide I’ll show you how to connect a solar panel to a charge controller in JUST 3 steps.

    To help you out, I’ve made a wiring diagram and step-by-step videos. Follow along and your charge controller will be wired and set up properly in no time.

    Materials Tools


    Note: I’ve sized the materials for my energy needs. You can copy them as-is or adjust as necessary.

    Step 1: Connect the Battery to the Charge Controller

    Note: These installation instructions should not supersede those in your charge controller’s or battery’s manual. Where these instructions differ from your manual’s, follow your manual!

    Check out the wiring diagram to see how to connect a solar panel to a charge controller:

    Here’s the important thing to know:

    Connect the battery to the charge controller FIRST. Then you connect the solar panel SECOND.

    If you do it in the wrong order, you can damage the charge controller. And that just wouldn’t be any fun.

    Ok! Let’s connect this battery.

    Connect the negative battery cable to the “-” battery terminal on the charge controller. Connect the positive battery cable to the “” battery terminal.

    Now connect the battery cables to the battery terminals. Connect negative first, then positive.

    Your charge controller should turn on or light up. For instance, mine has a light labeled “BATT” that turns on when the battery is properly connected.

    Your battery is now connected!

    Step 2: Connect the MC4 Solar Adapter Cables to the Solar Panel

    This step takes all of 20 seconds to do.

    Locate the MC4 connectors at the ends of your solar panel’s cables. There’ll be a male and a female one. They’ll look like this:

    Connect the MC4 inline fuse and positive solar adapter cable to the positive solar panel cable. Connect the negative solar adapter cable to the negative solar cable. Don’t let the exposed wires touch! ⚡

    Didn’t I say it’d take all of 20 seconds?

    Step 3: Connect the Solar Panel to the Charge Controller

    Your battery is connected.

    Your solar panel wires are ready to go.

    Now it’s time to do what you came here to do — connect solar panel to charge controller!

    connect, solar, panel, charge

    Connect the negative solar cable to the “-” solar terminal on the charge controller. Connect the positive solar cable to the “” solar terminal.

    Note: On some charge controllers, the solar terminals are labeled “PV.” This stands for “photovoltaic,” which refers to the method of producing energy using solar panels.

    Like before with the battery, the charge controller should light up or somehow indicate that the solar panel is properly connected.

    At this point, consult your charge controller’s manual to see if you need to program it at all. You may have to indicate your battery type, voltage, or other details.

    Fortunately for me, my controller’s default settings matched my system’s specs, so I didn’t have to change anything.

    And that’s it!

    Now you know how to connect a solar panel to a charge controller!

    Whenever you want to disconnect your solar panel, be sure to do everything in reverse order: disconnect the panel first, THEN disconnect the battery.

    Put your solar panel in the sun, and let it charge your battery with free solar energy. Relax and daydream about your next DIY solar power project.

    Tip: If you want some ideas on how to add on to this setup, check out my tutorial on making your first solar panel system.

    Solar Panel to Charge Controller Wiring FAQ

    Why do I need solar adapter cables?

    Your solar panel’s cables likely come with pre-attached MC4 connectors. MC4 connectors are great for connecting two solar PV wires together…

    …but they can’t connect to a charge controller. So we need solar adapter cables.

    Solar adapter cables have an MC4 connector on one end and are stripped at the other. That way, you can connect the MC4 connector to the solar panel cable and then connect the stripped end to the charge controller.

    What if my solar panel doesn’t have MC4 connectors?

    Buy some solar adapter cables with the connectors that match the ones on your solar panel wires.

    If you can’t find any, you might have to make your own by cutting two lengths of solar PV wire, stripping both ends, and crimping on matching connectors.

    Why isn’t my charge controller lighting up/turning on when I connect my solar panel?

    Your panel probably just needs some sun!

    Put it outside in direct sunlight. Your charge controller should light up or somehow indicate that the panel is properly connected and the battery is charging.

    If that doesn’t work, check your charge controller’s manual for troubleshooting.

    Rover Li 40 Amp MPPT Solar Charge Controller


    【Monitoring with Renogy ONE Core】 Add Renogy ONE Core to achieve Smart energy monitoring with intuitive visuals and real-time data. It is an upgraded streamlined energy with our 3-in-1 Smart panel.

    【Innovative MPPT Design】 Die-cast aluminium design ensuring excellent heat dissipation and Renogy Maximum Power Point Tracking technology with a high tracking efficiency of up to 99% and peak conversion efficiency of 98%. It is the best charging solution even in cloudy environments where the max power point of the solar panels will fluctuate all day.

    【12V/24V Automatically Detect】 Automatically detects 12V or 24V DC system voltages (for Non-Lithium battery types), and the LCD screen and multiple LED indicators display the solar charging and battery operation information, customizable parameters, and error codes.

    【Full System Protection】 Meant to safeguard your system, the self-diagnostic capability can assess and protect against reverse polarity, battery overcharging, battery over-discharging, overload, short-circuiting, and reverse current.

    【4-Stage Safely Charging】 Features 4-stage charging (Bulk, Absorption, Float, and Equalization) of Lead Acid Batteries and 2-stage charging (Bulk and Absorption) for Lithiuim batteries as well as Lithium Reactivation.

    【Diverse Load Control】 Connect DC appliances directly to the optional Load Terminals and monitor consumption or set up timer controls directly from the controller.

    【Remote Monitoring】 The RS232 communication port allows the Renogy Rover charge controller to communicate with the DC Home app and Renogy ONE M1 via the Renogy BT-1 Bluetooth module (highly recommend to add-on ). This will enable you to monitor the status and productivity of your panels on the go.

    The Renogy 40A Rover MPPT Charge Controller is the most efficient type of charge controller. With up to 99% tracking efficiency, the Rover ensures maximum power point solar charging that gets more energy to your battery bank. Capable of automatically detecting 12V/24V lead acid battery systems, this crucial component is preset to also work with Gel, Flooded (wet cell), and Sealed batteries(manual setting is required for 24V Lithium battery). When paired with the Renogy BT-1 Module and DC Home app you can view system performance in real-time and make parameter changes without having to get up!

    If you have any questions regarding this product, please call us at 1 (909) 287-7111 or submit a ticket for troubleshooting assistance.

    questions about your off-grid power system? Learn more from Renogy Learning Center !

    Package Includes

    Rover Li 40 Amp MPPT Charge Controller

    Remote Temperature Sensor

    Mounting Brackets

    Electrical Parameters Environmental Data
    Nominal System Voltage 12/24V Auto-Detect Protection Level IP32
    Rated Charge Current 40A Operating Temperature Range -35°C to 45°C;.31°F to 113°F
    Max. PV Input Voltage 100 VDC Storage Temperature Range -35°C to 75°C;.31°F to 167°F
    Max. PV Input Power 12V/520W, 24V/1040W Operating / Storage Humidity ≤ 90%, No Condensation
    Power Consumption <100mA/12V; <58mA/24V Temperature Compensation -3mV/°C/2V
    Max Battery Voltage 32V Accessories
    Ground Type Negative Temperature Sensor 9.8ft cable length
    Electrical Protection Overcharging, over-discharging, overload, and short circuit. Capable of charging over-discharged lithium batteries. Certifications
    Mechanical Specifications CE YES
    Dimensions 238 x 173 x 72.5 mm; 9.37 x 6.81 x 2.85 in FCC Class B Part 15 Compliant YES
    Weight 2.0kg / 4.41 lb Warranty
    Max. Terminals Size 8 AWG 10mm2 Material and workmanship warranty 2 Year
    Compatibility Operation Specifications
    Compatible PWM Charge Controller RNG-CTRL-WND10/RNG-CTRL-WND30-LI/RNG-CTRL-ADV30-LI Communication Protocol RS232
    Compatible MPPT Charge Controller RNG-CTRL-RVR20/RNG-CTRL-RVR30/RNG-CTRL-RVR40/ RNG-CTRL-RVR60S/RNG-CTRL-RVR100 Port Type RJ12
    Compatible App Renogy DC Home App available in both the App Store and Google Play Input Voltage 5V
    Protection Grade IP54
    Standby Power Consumption 0.04W
    Mechanical Specifications Operating Power Consumption 0.05W
    Communication Range ≤82ft (25m) Serial Baud Rate Fixed Baud Rate 9600bps
    Cable Length 16.4 ft (5.00m ) Certifications
    Dimensions 2.65 X 1.38 X 0.55 in (67.3 X 35 X 14 mm) FCC Class B Part 15 Compliant YES
    Weight 4.58oz (130g ) Warranty
    Operation Temperature -4°F to 185°F (‘-20℃~85℃) Material and workmanship warranty 2 Year

    What is the max wattage input on the Rover 40?

    The Renogy Rover 40A MPPT Solar Charge Controller can accept input of up to 520W for a 12V system, and up to 1040W for a 24V system.

    Does the Rover 40A MPPT charge controller have a built-in 40A fuse for the rated 40A load output?

    No. Please always add a fuse between the charge controller and batteries. To determine the fuse size, you can match it to the amperage rating of the charge controller. If you have one of our 40A charge controllers, we recommend using a 40A ANL fuse.

    What are the advantages of Renogy MPPT technology?

    Renogy Rover Series solar charge controllers use Power Catcher MPPT algorithm to always ensure the charge controller converts most energy by locking to the most optimal maximum power point.

    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. In particular, this controller will significantly increase the efficiency of a solar system where the solar panel voltage is much higher than the battery voltage.

    What is a Solar Charge Controller and what is MPPT?

    The Charge Controller takes the power made by the solar panels and transform the ‘solar panel power’ into a form of power that the batteries can use. MPPT stands for Maximum Power Point Tracking, and it relates to the solar cell itself. Each solar cell has a point at which the current (I) and voltage (V) output from the cell result in the maximum power output of the cell. MPPT ensures that you get the most power possible from your solar panels at any point in time. It is particularly effective during low light level conditions.

    What are the advantages of Renogy MPPT technology?

    Renogy Rover series solar charge controller uses the most advanced Maximum Power Point Tracking (MPPT) technology to track solar panels’ maximum power voltage point as it varies depending on sunlight exposure and temperature. This technology ensures the maximum efficiency of your solar system and significantly outperforms standard PWM solar controllers. Another benefit of MPPT technology is the wide solar input voltage range. This controller can work with standard off-grid 12/24V solar panels and with high voltage or multiple panels with voltage up to 100V.

    questions about your off-grid power system? Learn more from Renogy Learning Center !

    Solar Charge Controller Settings

    A solar charge controller has various settings that need to be altered for it to function properly, such as voltage ampere settings. Today you will get to know about solar charge controller settings along with solar charge controller voltage settings.

    Solar Charge Controller

    The amount of power generated from the solar panel travels to the inverter batteries. This power needs to be maintained and regulated. A solar charge controller is used for this purpose. It sends short energy pulses to the battery. The average output produced by an MPPT solar charge controller can be 42 volts. You will require additional batteries to produce higher voltages. Here is the catch: to prevent your batteries from damage, you need to choose the right solar charge controller.

    Solar Charge Controller Settings

    Just installing a charge controller won’t solve all your problems. There are different settings that need to be checked and manually adjusted. Different types of batteries like Lithium Iron Phosphate (LIPO), lithium, iron phosphate, lead-acid, and Absorbent Glass Mat (AGM) batteries have different settings. However, there are only two types of charge controllers.

    MPPT controller or maximum power-point tracking controller

    PWM controller or pulse width modulation controller

    Before starting to set up the solar charge controller, you need to understand its functioning of it. Here are the points that you need to keep a note of while installing and setting up the solar charge controller.

    Once the battery is fully charged, the battery will not hold more solar energy in comparison to the chemical content.

    • If the battery is charged high, it can result in the development of heat and gas inside the battery.
    • Electrolytes inside the battery began to expand. This further led to the development of bubbles.
    • This chemical process leads to the generation of hydrogen gas, which is explosive.
    • An overcharged battery will decrease the capacity and increase the aging process of the battery.

    The Parameters:

    Battery Floating Charging Voltage

    The voltage at which a battery is maintained once it is fully charged is known as the battery floating charging voltage. This voltage maintains the capacity of the battery by self-discharging it. The typical voltage for a 12V system is 13.7V and for a 24 V system, it is 27.4V. 58.4V is the voltage for a 48V system.

    Battery Over-Discharging Protection Voltage

    It is also known as under voltage cutoff voltage and its value should also be in accordance with the battery type. In solar charge controller settings, the voltage value range for a 12V system is 10.8V to 11.4V. For a 24V system, it is 21.6V to 22.8V, and 43.2V to 45.6V for a 48 V system. So, the typical values are 11.1 V, 22.2 V, and 44.4 V.

    Battery Overcharging Protection Voltage

    This voltage value should be set as per the battery type. This voltage is also termed a fully charged cutoff voltage or over-voltage cutoff voltage. This voltage value for a 12-volt system ranges between 14.1 V and 14.5 V. For a 24-volt system, it is 28.2V to 29V and for a 48V system, it is 56.4V to 58V. So overall, the typical value for the voltage is 14.4V, 28.8V, and 57.6V.

    Charge Controller Capacity

    It is the maximum number of amperes that your solar charge controller can handle. It is the parameter on the basis of which a solar charge controller is rated. It can be 10A, 20A, 30A, 40A, 50A, 60A, 80A, or 100A.

    Maximum Charging Current

    It is the maximum output current of the solar panels or solar arrays. It is the output that you receive from the batteries.

    System Voltage

    It is also known as the Rated Operational Voltage of your solar power system which refers to the battery bank voltage (direct current operational voltage). Usually, the value is 12V, 24V, or 48V. However, a medium-scale or a large-scale charge controller system has voltage values of 110V and 220V.

    Solar Charge Controller Voltage Settings

    These are the most critical settings that need to be done carefully for the better functioning of the solar charge controller. A solar charge controller is capable of handling a variety of battery voltages ranging from 12 volts to 72 volts. As per the basic solar charge controller settings, it is capable of accommodating a maximum input voltage of 12 volts or 24 volts.

    You need to set the voltage and current parameters before you start using the charge controller. This can be done by adjusting the voltage settings. Here is the list mentioning the most critical voltage settings for the solar charge controller.

    • Absorption Duration: (Adaptive/Fixed)
    • Absorption Voltage: 14.60 volts
    • Automatic Equalization: (Disabled / Equalize every X Days) Disabled
    • Equalization Current Percentage: 25%
    • Equalization Duration: 4 hours
    • Equalization stop mode: (Fixed Time / Automatic on Voltage) Fixed time
    • Equalization Voltage: 14.40 volts
    • Float Voltage: 13.50 volts
    • Low-Temperature Cutoff (optional): Disabled
    • Maximum Absorption Time: 6 hours to 3 minutes (max) per 100Ah battery capacity
    • Maximum Absorption Rate: 30 minutes per 100Ah battery capacity
    • Manual Equalization: Select start now
    • Maximum Equalization Duration: 3-4 hours
    • Re-Bulk Voltage offset: 0.1 volts
    • Tail Current: 2.0A
    • Temperature Compensation (mV/°C): 27.7 volts / 40° Celsius-25° Celsius

    Note: Settings can be changed manually on the controller or from the PC Software. Follow the instructions of the manufacturer for the best results.

    Steps in Solar Charge Controller Settings

    While you set up your new solar charge controller, you should begin with properly wiring the controller to the battery bank and solar panels properly. Once the wiring is properly done and the controller detects the power, its screen will light up. Other steps are as follows:

    connect, solar, panel, charge

    Enter the settings menu by holding the menu button for a few seconds.

    Charge current PV to Battery will be displayed

    Battery Type Selection can be done by pressing the menu button for a long time.

    The battery voltage will be auto-detected by the controller.

    According to the user manual, set the setting for absorption charge voltage, low voltage cutoff value, float charge voltage, and low voltage recovery value.

    If the system has an option for setting up the discharge value for DC, then set it as per the user manual.

    Once the setting is done, the charge controller will instantly start the charging process.

    PWM Solar Charge Controller User Manual

    The user manual of a PWM or a pulse width modulation solar charge controller contains information regarding the following:

    LCD Display or Key

    A solar charge controller has a digital display that displays a number of things on the panel through abbreviations or signs and symbols. Here is the list of those things and what they mean.

    • A panel with a small sun shining indicates the solar panel charge.
    • An arrow near the panel when it is bold black means the system is on Aqualation or buck when the arrow is flicking it means it is on float mode.
    • A square filled with horizontal bars indicates battery.
    • Near the battery sign, there is an arrow indicating the output.
    • A bulb sign indicates the load
    • V% indicates the voltage
    • AH is for ampere hours
    • A square-shaped box indicates a menu. It is used for switching between different displays. You can enter or exit the setting by pressing it for a long time.
    • An up arrow is used to increase the value
    • A down arrow showing a decrease in the value

    LCD Display or Setting

    To browse different interfaces in the solar charge controller settings, press the menu button. The LCD or key display discussed in point 1 is the main display. Next displays in order when you press the menu are:

    • FloatVoltage – The screen shows LIT, voltage, and the battery
    • Discharge Reconnect – Shows LIT, voltage, battery, output (arrow), and load (bulb)
    • Under voltage Protection – Displays LIT, voltage, empty battery symbol, and load (bulb)
    • Work Mode – It displays hours (H), output (arrow), and load (bulb). OH, means dawn to dusk, 24H means load output is for 24 hours, and 1-23H means the load is on after sunset and closed after sunrise hours.
    • Battery Type – LIT and the battery box with horizontal bars, determine the amount of battery charged and the type of battery. LIT is for lithium. After this, you are again on the main display.

    Important: To switch On or Off the load manually on the main display, press the down key.

    Product Features

    • 3-stage PWM charge management
    • A built-in industrial microcontroller with adjustable parameters
    • A pulse width modulation solar charge controller has the following features:
    • Battery Switching functions between lithium and lead battery. The lithium battery is the default setting and switches it to the battery type interface by holding it for 3 seconds.
    • Dual metal–oxide–semiconductor field-effect transistor (MOSFET) Reverse current protection with low heating dissipation
    • In-built protection for short-circuit open circuits, overload, and reverse

    Safety Instructions

    Every electrical appliance comes with a list of safety instructions that are prepared according to the appliance. A PWM controller has the following safety instructions mentioned in its user manual.

    • Do not connect another charging source with the charge controller. The controller is suitable only for regulating solar modules.
    • For the controller to recognize the battery type, ensure the battery has enough voltage before you begin the installation process.
    • Install the controller on a well-ventilated and flat surface. While running, the controller will be heated.
    • This controller is suitable for lithium batteries. All kinds of lead batteries (open, AGM, and gel) are also compatible with it.
    • To minimize loss, keep the battery cable as short as possible.

    System Connection

    In solar charge controller settings, it contains instructions related to the connection. It tells you which port you need to connect to which wire.

    • Connect the battery to the charge regulator (plus and minus)
    • Connect the consumer to the charge regulator (plus and minus)
    • Connect the photovoltaic module to the charge regulator (plus and minus)

    Technical Parameter

    This section contains all the information regarding the voltage, amperes, input, output, size, weight, etc. of the PWM solar charge controller.

    • Batt voltage – 12 volts / 24 volts auto adapt.
    • Charge current – 10A (KYZ 10), 20A (KYZ 20), 30A (KYZ 30)
    • Discharge current – 10A (KYZ 10), 10A (KYZ 20), 10A (KYZ 30)
    • Max solar input – less than 41 volts
    • Model – (KYZ 10) (KYZ 20) (KYZ 30)
    • Operating temperature –.35 ~60° Celsius
    • Size or weight – 13370355 millimeters or 140 grams
    • Standby current – greater than 10 mA
    • USB output – 5 volts / 2 A Max

    The technical parameters of lithium and lead batteries under certain parameters are mentioned in the table below.

    Type of Battery Equalization Float Undervoltage Protection Discharge Reconnect
    Lithium (LIT) battery 12.8 volts 12.0 volts (default, adjustable range 11.5-12.8 volts) 10.7 volts (defaults, adjustable range 9.0-11.0volts) 11.6 volts(defaults, adjustable range 11.0-11.7volts)
    Lead acid battery (bAt) 14.4 volts 13.7 Volts (defaults, adjustable range13-15V) 10.7V (defaults, adjustable range9.0-11.0 Volts) 11.6 Volts (defaults, adjustable range11.0-11.7V)

    Trouble Shooting

    Every electronic appliance faces some problem that can be easily resolved with troubleshooting. The basic problem and its solution are mentioned under the troubleshooting column in the PWMM user manual. Here I have mentioned the problem – probable cause – solution.

    • Charge icon not on when sunny – Solar panel is open or reversed – Reconnect
    • Load icon off – Battery low – Recharge
    • Load icon off – Mode setting wrong – Set again
    • Load icon slow flashing – Overload – Reduce load watt
    • Load icon slow flashing – Short circuit protection – Auto-reconnect
    • Power off – Battery too low reverse – Check battery or connection

    Solar Charge Controller 24V Settings

    After the solar charge controller settings for a 12V system, the 24V system is the most common charge controller used in residential solar power systems. The basic settings for this are mentioned in the user manual of your charge controller. However, here are a few basic settings that are for a 24V system.

    • Battery Floating Charging Voltage is 27.4V
    • Battery Over-discharging Protection Voltage is 21.6V to 22.8V
    • Battery Overcharging Protection Voltage is 28.2V to 29V
    • Solar charge controller settings for AGM battery

    The solar charge controller setting for an AGM or Absorbent Glass Mat battery is also for 12 volts, 24 volts, or 48 volts. The maximum charge current should be at 50A maximum per 100Ah battery capacity. The absorption voltage should be 14.60 volts and the float voltage at 13.50 volts. Equalization voltage at 14.40 volts and bulk voltage offset at 0.10 volts. Absorption duration should be adaptive, and duration should be between 6 hours to 30 minutes per 100Ah battery capacity. The current percentage for equalization is at 25% and its duration at 4 hours max.

    Solar Charge Controller Settings for Lithium Batteries

    Before you begin setting up your lithium batteries, remember that lithium batteries do not require temperature compensation. Also, if you are replacing lead batteries with lithium batteries and the settings are set at Equalized this needs to be changed. To change this, select, EQE (Master equalizer enable/disable) on the charge controller display. This can also be done by selecting OFF the dip switch in other controllers. Some common settings for a multi-stage charge profile need to be set to the following settings:

    • Charge voltage – 14.4 volts (3.6 VPC)
    • Absorption time – 30 minutes to balance lithium cells
    • Float voltage – 13.6 volts
    • Resting voltage (default) – 3.4 VPC

    Solar Charge Controller Settings for Lead Acid Battery

    The lead acid battery is a classic configuration in a solar power system. Once you convert the battery type from lithium/AGM to lead acid battery, the original set parameters for a lead acid battery will be used. These configurations are already installed in the charge controller system. And sometimes, it is just plugging and using the system.

    Well, today you learned about the alteration in solar charge controller settings in accordance with the type of batteries your inverter has. Also, solar charge controller voltage settings should be carefully done to get the maximum potential output from the solar charge controller.

    Olivia is committed to green energy and works to help ensure our planet’s long-term habitability. She takes part in environmental conservation by recycling and avoiding single-use plastic.

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    2 Комментарии и мнения владельцев

    Hello, very nice article! Could I have 2 questions: 1.) I have the same type controller. Do you know, why my solar controller is changing battery setup from B03 to B01 by itself? Is it damaged? 2.) Now I miss arrow on display between solar panel and battery. Does it mean, that battery is fully charged? Thank you.

    Dear Jaro, Thankyou for reaching out to us. For Query 1: Solar Charge Controller changing battery setup from B03 to B01. We have found that said settings mean as follows: B03 – Battery Over Voltage – This error occurs when Input voltage to battery terminals exceeds 17.5-V B01 – Battery Disconnected – This fault code appears when the Portable solar kit cannot detect a battery bank. The issue you are facing can be due to the following reasons: 1- Automatic Configuration – Some controllers adjust their settings based on the battery type and conditions they detect. Check your controller’s manual to see if it has this feature and disable it, according to instrcutions listed in the manual. 2- Firmware or Software Issue: Glitches in the controller’s firmware or software can cause unexpected behavior. Check for firmware updates or try resetting the controller to its factory settings. If this doesnt work, contact the manufacturer to get the controller checked for damage and for possible repair. For Query 2: Arrow on Display between Solar Panel and Battery It is difficult to determine the exact meaning without knowing your controller’s model. 1- In some cases, the arrow indicates charging. 2- It could also mean the battery is fully charged. 3- Or, there might be an issue the controller requires a reset. Follow steps listed in the manual to do the same. And if the issue is still unresolved, there could be some issues with wiring between the 3 components. Last option is to get the entire system checked by an authorized technician and contact the manufacturer for assistance.

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    What Is Solar Charge Controller? Do You Need One?

    Depending on the kind of solarstorage system you have, you may or may not need one.

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    A solar charge controller benefits a solarstorage system. The solarstorage system allows customers to use solar off-grid, either full-time or as a backup during power outages. The controller controls the amount of energy being sent into the battery backup so that the battery doesn’t exceed its voltage capacity—thereby extending the life of the battery and avoiding any damage to it.

    Depending on the kind of solarstorage system you have, you may or may not need a solar charge controller. In this article, we’ll go through everything you need to know about this tool.

    Benefits and Types

    The output of a solar panel can vary depending on levels of sunlight, ambient temperature, the quality of the solar cells in the panel, and other factors. All of these factors affect the efficiency of the panels in converting sunlight into electricity.

    A solar charge controller smooths out that variability so that batteries receive power at a constant and safe rate. It also sends a “trickle charge” when the battery is nearly full. Since batteries regularly lose a small amount of charge, a trickle charge keeps the battery topped off without overcharging it.

    If you have a grid-tied solarstorage system, either ground-mounted or on your roof, you most likely have no need for a solar charge controller. Your excess solar energy will automatically flow into the grid when your battery is full. But if your solar system is operating off-grid, a controller might be a wise investment.

    There are two main types of solar charge controllers, Pulse Width Modulated (PWM) and Maximum Power Point Tracking (MPPT). PWM controllers are better suited for small solarstorage systems with low voltage panels and small batteries. MPPT controllers are more expensive, but have more features and advantages; they are recommended for any solar system over 170 watts.

    PWM Controllers

    The main function of a PWM controller is to protect your battery by making sure solar panels have the same voltage as the battery. The voltage of the battery must match the “nominal voltage” of a solar panel—that is, the voltage the panel is marketed as having, even if the actual voltage can vary and often be slightly higher.

    As its name suggests, a PWM controller controls the flow by pulsing the power sent to the battery to slow down or speed up the charging. Some PWM controllers can only handle one voltage level, while others can handle different levels. Either way, the voltage of both battery and panel must still be the same.

    connect, solar, panel, charge

    PWM controllers are uncomplicated devices, though some can have additional features added to their essentially basic systems.

    MPPT Controllers

    Unlike PWM systems, where the voltage of battery and panels must be the same, MPPT controllers can charge a lower voltage battery from a higher voltage solar array and, in some cases, a higher voltage battery from a lower voltage solar array.

    In electrical systems, voltage and amperage are inversely related: The higher the voltage, the lower the current (amperage), and vice versa. Since an MPPT controller controls the rate and current of the voltage flowing from solar panels to a battery, off-grid solarstorage systems can have panels of different voltage than their batteries.

    So while a solar panel by itself with a nominal voltage of 24 volts is insufficient to power a 48-volt battery, an MPPT controller allows it to work by halving the amperage, thereby doubling the voltage flowing into the battery.

    Treehugger Tip

    For fans of golfing or boondocking (off-grid RV living), an MPPT controller allows you to charge a 36-volt or 48-volt battery with a single flexible 12-volt solar panel attached to the roof of your RV or golf cart.

    MPPT controllers can increase the efficiency of your solar panels by 20% to 30% by tracking the optimal voltage-to-current ratio to maximize output to a battery. It’s their increased efficiency that can make their higher cost worth it.


    The simplest PWM controllers can cost as little as 20. Those with additional features can cost up to 200 or more.

    MPPT controllers can do more, but cost more, running from 50 to over 1,000, depending on the features. If there is a long distance between your panels and battery, however, you can save money by using lower-gauge electrical wiring between the two, since MPPT controllers modulate current and voltage.

    And because MPPT controllers can convert the higher output of a solar array to the lower voltage of a battery, a battery can capture more of the sun’s energy. This will increase its efficiency and potentially shorten the payback time of the more expensive system, as well as increase your ability to rely solely on solar energy.

    Some optional controller features that come at additional costs include:

    • LEDs to allow users to monitor the voltage and amperage of the system.
    • Internet-enabled controllers to allow for remote monitoring.
    • Multiple outputs to allow for charging two separate batteries.
    • Longer cables for greater distances between panels and battery.
    • Temperature sensors, which will maximize the efficiency of charging since batteries charge at different rates during different temperatures.
    • Low voltage disconnects, which will automatically disconnect an attached DC-operated device (such as a golf cart) when the battery is low.

    As always with solar products, anticipate your solar needs and capabilities, and calculate the costs and payback time to see what kind of system works best for you.

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