Wiring solar panels, charge controller and battery together
One of the most common questions we get is Can I connect my solar panels directly to the battery? While technically you can, we strongly advise against it. A battery is a fragile thing and high voltage of solar panels can easily destroy it. A charge controller acts as a safety barrier between panels and a battery and should be a part of every home solar panel installation. In this article we’ll explain how to wire together solar panels, a regulator and a battery.
Charge controller keeps your battery safe
But what does a battery fear? From what a controller actually protects it? Well, a charge controller
-
lowers the voltage of panels down to the level of the battery. When the battery is directly connected to panels whose voltage is higher, the battery heats up. Not only does it decrease the lifespan of a battery, it can potentially lead to its explosion.
PWM and MPPT are interchangeable in cases when the voltage of the solar panels is slightly higher than the voltage of the battery. For example, you can install either of them with 30-cell panels and a 12V battery or 60-cell panels and a 24V battery. However, even in these cases MPPT-controller allows you to harvest 20-25% more energy. This type of solar regulator is especially good in winter, when panels reach their voltage peaks.
PWM-controller
- lower price: 20-100
- 15 year lifespan
- 2-4 times smaller than MPPT
- 75-85% low efficiency
- works well only when the voltage of panels is slightly higher than the voltage of a battery
MPPT-controller
- 90-95% efficiency
- converts extra voltage of panels into current
- manages charging process
- built-in Bluetooth to connect to to a laptop or a smartphone
- 10-15 year lifespan
- more expensive than a PWM-controller: 100-1,000
Look for maximum volts and amps when sizing a controller
Before purchasing a charge controller, make sure it fits the solar panel system. The main parameter you’re looking for is maximum amps. Amps of a controller must be bigger than the combined power of all solar panels divided by the voltage of the battery.
Let’s say we have two 300W panels and a 12V battery. Now we calculate the amps:
300W 2 panels / 12 V = 50 A Let’s add 25% for safety. During cold days panels produce more current than usual and it’s better to be ready for it:
50 A 1.25 = 62.5 A The size of a controller must be bigger than 62.5 A.
Connecting battery, controller and panels
Whether you have a PWM-controller or an MPPT-regulator, the procedure of hooking it up with the battery and panels remains the same. Normally there are three wiring sections on a charge controller: one for panels, one for a battery and one for DC loads.
Battery
Take a simple stranded copper core wire. 2. Use the black wire to match the charge controller minus with the battery minus. 3. Use the red wire to match the charge controller plus with the battery plus 4. Screw the wires tightly into the charge controller.
Turn the charge controller on: it should be able to measure the charge of the battery. In the user manual of a charge controller there should be a wiring diagram, which you can consult if in doubt.
PV modules
After you’ve connected the charge controller with the battery, it is now safe to connect it to panels. Out of the junction box of a panel come two cables, a positive and a negative. In some situations it’s just two wires that go straight to the controller. often, there are so-called MC4 connectors on each end, a male connector for the positive cable and female for the negative one.
Connect MC4 connectors with a complementary pair of connectors with wires on other ends. If you have two wires coming out straight of the junction box, skip this step. 2. Plug these wires into the regulator: positive into plus, negative into minus. 3. Once you’ve connected the panels to the controller, it should be able to recognise them. Check the status of your array on the charge controller screen. 4. PV modules start to generate electricity as soon as they face the sun.
Here’s the diagram, which gives an idea on how to connect these parts of a solar panel system together. We have one 12V KiloVault solar battery, one 96A Midnite MPPT-controller and two 330W Panasonic solar panels.
If you have several solar panels, like on the diagram, the positive cable of one panel usually goes to the negative terminal of the adjacent one. Then, the negative cable of the first panel and the positive cable of the last panel go into the charge controller. These panels are connected in series, which means that their voltage is combined, but an amperage stays the same.
In this small panel system, each of the panels has a voltage of approximately 38V. Since panels are connected in series, their combined voltage is 38V 2 = 76V. Their amperage is
The voltage of the battery is 12V. A PWM-controller would just cut down the voltage of panels down to the level of battery. Therefore, you would make use only of 8.7A 12V = 104W of power for the whole array of 660 W. However, since we have an MPPT charge controller, it lets panels retain their power and speeds up the charging process of the battery. This battery in theory can receive 660W ÷ 12V = 55A of current.
Calculate your solar system
Our Grid-Tied Solar System Calculator will help you choose the right solar panels and accessories to cover your energy needs.
How To Install And Configure EPEVER Solar Charge Controller
I bought this EPEVER Tracer MPPT Solar Charge Controller 6 Months ago from AliExpress. up to date it has been operating in good working condition. The Model that I purchased was 4210AN, this model support rated charge Current of 40A, which suit my Current Solar Panel Setup. In this Post I will Share how to select the Correct MPPT Charge Controller base on your Require Solar Panel Setup ,how to install and mount it to the electrical panel. how to program and configure the EPEVER Solar Charge Controller, finally i will provide my honest review about this product.
Note : This is not a Sponsored post. just my honest review after using the product.
Before purchasing the EPEVER mppt solar charge controller, i will need to calculate what are the total charge current of my existing Solar Panel Setup.
My Current Solar Setup are being wired in Parallel together, with 5 pieces of 100W Power 18v Solar Panel with a charge current rated at 7A per pieces.
The Below Diagram Shows my Current Solar Panel Wiring Setup
Below show the actual physical Setup
How to Calculate Solar Panel Current connected in Parallel ?
The Total Output Current is the Resulting summation of All the rated Output Current of the Solar Panel connected in Parallel
Total Current = 7A 7A 7A7A 7A = 35A
I would allocate a Safe margin factor of 15% on top of the total rated Current
New Total Current with 15% safety margin = 35A x1.15 = 40.25A
Thus I will need to purchase a MPPT Charge Controller with a charge rated current equal or more than 40.25A.
Where and how to Source For a Suitable MPPT Charge Controller ?
There are a few online spaces. where you can source for a suitable MPPT Solar Charge Controller. Ecommerce site such as Amazon. Aliexpress, Alibaba. Lazada, Shopee etc have a tonne of Seller selling different brand of MPPT Solar Charge Controller.
I bought this EPEVER MPPT Charge Controller from AliExpress. Before purchasing the Controller. please make sure to identify the correct model you will need to purchase base on the Calculated total output Current of your Solar Panel Setup.
Identify the Correct Model
How to mount the MPPT Solar Charge Controller to your Electrical Panel ?
To mount the Solar Charge Controller into your Electrical Panel. you will need some Self Drill Screws. A Battery powered Electric Drill and a Phillip Screw Driver.
Step 1- Mark the area that you are going to drill
Step 2- Ensure that All Power Source and Switches are turn Off
How to Wire up EPEVER MPPT Solar Charge Controller
Prior connecting Solar Panel Wiring and Battery Wiring to EPEVER Solar Charge Controller. We will need to Identify what are the Cable size that we will need for our Systems.
For Solar Panel PV Wiring
Solar Panel PV Wiring size is determine by its ISC( Short Circuit Current ). You will be able to find this Information on your PV Specification Label.
ISC Calculation For Parallel Connected Solar Panel
When PV Modules are connected in Parallel. the total ISC is equal to the summation of Individual PV Module ISC.
ISC Calculation For Series Connected Solar Panel
When PV Modules are connected in Series. the system final ISC Value will equal to the PV Panel with the smallest ISC Value.
Miscellaneous Electrical Parts That you will need before connecting the PV Wire and Battery Cable to the MPPT Charge Controller
Breaker From Solar Panel to MPPT Charge Controller
In Order to Protect any surge Current from your PV System. it will be safer to install a breaker between the PV and the MPPT Charge Controller.
Do note that the Solar Panel is producing Direct Current. Thus the Circuit Breaker Type that we should be looking for. will need to be a DC Type Circuit Breaker.
We can either purchase a Single Pole Type or Duo Pole Type DC Circuit Breaker. If you planned to use a Single Pole Type DC Circuit Breaker. only the positive pole Cable need to be connected to the Circuit breaker. while for the Negative pole Cable you will need to connect it together or link it together with some bus bar. But If you planned to use a Duo Pole Type DC Circuit Breaker. both positive pole and negative pole Cable from the PV Panel will be connected to the Breaker.
For my System I am using a 32A and 16A Circuit Breaker. as i couldn’t find a 40A Circuit Breaker available.
Breaker From MPPT Charge Controller to Battery
Breaker from MPPT Charge Controller to Battery might not be necessary. as the Charging Current is regulated by the MPPT Charge Controller. But it will be a plus to add a breaker in between. if under some circumstances User is able to cut off the Charging Current from the Solar Charger to Battery without disconnecting any cable.
Tools that you will need to Wire up the Solar Panel Cable and Battery Cable to your MPPT Charge Controller
ok. now we have already size the correct Cable and equipment. next step is t o connect up everything.
- Cutter
- Wire Stripper ( is a Plus)
- Phillip / Flat Head Screw Driver
- Electrical Tape
How To Program and Configure EPEVER MPPT Charge Controller
Basically there are not much Configuration need to be done
The Only main thing. that we will need to configure is to set the Correct battery Type
Configurating Battery Type
Step 1. Press Select Button until you see the Battery Voltage Interface
Step 2. Press and hold the Enter Button until you see the Battery.Type Interface flashes
Step 3. Select Button to change the Battery Type. In my System I am using Lithium Ion Battery so i select F04
Verify Whether your Installation and Configuration is Working Properly
First Verification- Press Select button and cycle to the PV Screen. you will be able to see. a Sun Symbol / Solar Panel / Battery and kwh. This indicate that your Panel is Charging the Battery
Second Verification- Press Select button and cycle to the Battery Screen. you will be able to see. a Sun Symbol / Solar Panel / Battery and kwh. This indicate that your Battery is In Charging Mode
Third Verification- Press Select button and cycle to the PV Voltage Screen. Check whether the PV Voltage is around your Solar Panel Voltage Specification
ok, If all the Check point above are good. congratulation Your installation and configuration is success.
How To Troubleshoot EPEVER MPPT Solar Charge Controller
Life aren’t always Smooth right. now you might run into some Trouble
Below is the Table I Extracted from EPEVER Manual. you can use that as a Reference to Conduct Troubleshooting
Restart Controller or Press button to clear fault
My Personal Review For EPEVER MPPT Solar Charge Controller
The Controller. had been installed and running in my Solar System for almost half a year. Up to date it is still in good working condition. The Unit Disperse heat very well, so far i did not encounter any equipment overheated situation. Functionality wise it work well. and i did not encounter any break down events.
Check Out my Other DIY Post
How to program the MT50 solar charge control display interface
The MT50 is a remote meter for EPEver / EPSolar charge controllers and enables easier configuration and the ability to see the charge controller status on more convenient places in e.g. an RV. This guide covers common tasks and configurations, step-by-step.
Connect the MT50 to a charge controller
Use the cable the comes with the MT50, connect one end into the data port of the charge controller, and the other into the MT50. You should immediately get the charge controller status on the MT50 display. If not, check if the charge controller is actually running, and that the cable is properly connected. Make sure the MT50 is compatible with your charge controller model. It should work with all EPEver / EPSolar LSxxxxB(P), VSxxxxBN, and TracerxxxxBN(P) controllers.
MT50 real-time monitoring
The MT50 shows the most important information you need from your solar power system:
- If the solar panel is generating electricity, what’s the voltage from the solar panel, and how much power is it delivering (amps).
- The status of the battery, the voltage, and how much power it is charging with (amps).
- The load (on or off), and how much energy is being used by appliances connected to the solar charge controller.
We’ve experienced that the battery status symbol and smiley face can be a bit misleading, and not necessarily reflect the actual state of the battery. You should instead look at the voltage; If above 12V, you’re good, but if it’s below 11V, you should cut the load and let it charge for a while. That being said, if you’re having a heavy load on the battery, e.g. through an inverter that is directly connected to it, the voltage reading may be low as the long as the current is high. The actual state of charge is most correct when the battery is idle (no charge or discharge).
Navigating the MT50
The EPEver MT50 remote meter has 6 buttons underneath the display: Esc, Left, Up, Down, Right, and OK. In general, the OK button is used to enter menus and save options, the arrows are used for navigation and changing values and options, and the Esc button is used to go back or exit the menu.
When pressing the OK button, you will first enter the menu. Pressing OK once more, you get the subpages on the chosen menu item, and pressing OK once again, you can change the parameters for that subpage. Pressing Esc takes you the same way backward.
Changing values might require a password. The default password for the EPEver MT50 is 000000. If you change several settings in the same session, you will not be asked for the password every time, but you will be logged out after about 10 minutes.
Finding your charge controller model ID with the MT50
To get information about your charge controller, press Esc to enter the main menu. Use the Down button to navigate to 2. Device info, then press OK to enter it. On the first page, you will find the model, what voltage it is rated for, max charge current, and max discharge current. Press the Down button to go to the second page to see the serial number of your charge controller device.
Change the charge controller date with the MT50
From the main screen, press Esc to enter the menu. Use the Down button to navigate to 6. Device Para. and press OK to enter it. You will see a page with an ID number (usually ID: 001). Press the Down button and you will get the page with the date and time settings. Press the OK button to be able to change it. You might be asked to enter a password. If you haven’t changed it, the default password is 000000. Press OK. Use the Right and Left button to select the different parameters, which are:
- Backlight time: The number of seconds the backlight should be on when inactive.
- Month
- Date
- Year
- Hour
- Minute
- Second
If you’re done doing any changes, press the OK button. When prompted with either Save or Cancel, Save is selected by default and you can press OK to save the changes. If you don’t want to save, press the Right button so that Cancel is selected, then press OK.
Press Esc until you’re back at the main page.
Can I use an ethernet cable to connect the MT50 to the charge controller instead of the included one?
Yes, you can. It’s sometimes more convenient if you’re pulling the cable through cabinets or walls (for instance in an RV camper) to create holes only big enough for the cable to go through. Use a normal CAT5 ethernet cable without plugs, at least not at the end that you’re pulling through the holes. Then, use a proper tool to put a new RJ45 plug onto the cable. Just make sure the connectors are located correctly. If not, it may damage your MT50 remote meter, and possibly the charge controller as well.
The following video shows how to attach the RJ45 plug to an ethernet cable:
Warning! Despite using a network cable, neither the charge controller nor the MT50 can be connected to a PC network port, a router, or any other network device.
If you want to connect the charge controller to a PC, you must use a special RS485 to USB cable and the solar station monitor software from EPEver.
What Are Charge Controller Settings? (Key Details)
The profile setting on a solar charge controller sets up the power output parameters to charge the battery bank in the most optimal voltage and current based on the battery chemistry used. Lead-acid, Absorbent Glass Mat (AGM), and Lithium Iron Phosphate (LFP) type batteries have different optimum charging parameters.
The battery manufacturer defines the charge controller settings, such as charge voltage and current, to ensure optimal charging conditions and battery longevity. The settings are specific to each brand and type of battery and must be adhered to, to maintain your battery warranty.
Battery manufacturers list their recommended charging parameters on their product websites or supply them as part of the support documentation when purchasing the device.
important Charge Controller parameters;
Let’s review these parameters and understand what they mean and what role they play?
How Do Charge Controller Settings Work?
The battery manufacturer defines the charge controller settings according to the type of battery chemistry and battery bank setup.
The parameters are programmed for the battery charging parameters, load output parameters, programmable relay settings, external device settings, firmware update settings, Bluetooth enabled/disabled, and networking setup.
Battery manufacturer websites and user manuals typically provide the charge controller settings required for optimal charging and battery protection. If this data is not supplied, the manufacturer’s technical support contact can be requested for it.
The most critical settings For Charge Controllers:
- Absorption Voltage:
- Float Voltage:
- Equalization Voltage:
- Re-Bulk Voltage offset:
- Absorption Duration: (Adaptive/Fixed)
- Maximum Absorption Time:
- Tail Current:
- Equalization Current Percentage:
- Automatic Equalization: (Disabled / Equalize every X Days)
- Equalization stop mode: (Fixed Time / Automatic on Voltage)
- Maximum Equalization Duration:
- Temperature Compensation (mV/°C):
- Low-Temperature Cutoff (optional):
Also, request the method of programming for these settings to be supplied. Most Smart MPPT charge controllers can be programmed via a mobile application interface. Older models have switch dials that must be set in certain combinations to achieve the desired settings.
A simple e-mail request to the battery manufacturer technical support requesting the above settings should prove effective.
Also, please provide them with a brief description of your solar systems, such as the type and number of solar panels and the make and model of the charge controller.
How To Set Up A Charge Controller – Example
I will discuss an example of how the settings are loaded for a Victron Smart Solar Charge Controller via the mobile application interface. Mobile applications are the easiest way to interface with the charge controller and to set parameters and monitor performance.
- Download and install the mobile application on your smartphone
- Open the mobile application on your smartphone
- Select the Charge Controller to be programmed on the “Device List.”
- Select the Settings Cog in the upper right-hand corner
- Select the “Battery” menu
- Enter the values specified by the battery manufacturer for Battle Born LiFePO4 Batteries.
- Battery Voltage (12V/24V/48V)
- Maximum Charge Current (30A) – 50A maximum per 100Ah battery capacity
- Charger Enabled
- Battery preset – User defined
- Expert mode Enabled
- Absorption Voltage – 14.60V
- Float Voltage – 13.50V
- Equalization Voltage – 14.40V
- Bulk Voltage Offset – 0.10V
- Absorption Duration – Adaptive
- Maximum Absorption Time – 6 hours – 30 minutes per 100Ah battery capacity
- Tail Current – 2.0A
- Equalization Settings
- Equalization Current Percentage – 25%
- Automatic Equalization – Disabled
- Equalization Stop Mode – Fixed Time
- Equalization Duration – 4 hours
- Manual Equalization – Select (Start Now)
- Voltage Temperature Compensation – Disabled
- Battery Limits – Low-Temperature Cutoff – Disabled
- Once the settings are loaded, they are automatically saved and active.
The charge controller settings have now been set, and you can activate the system to start charging the batteries.
Monitor the charging via the mobile application and use a voltmeter to verify the output voltage going into the battery bank.
Why Careful Recording Of Charge Controller Settings Are Important
Battery manufacturers will warrant their products for as much as ten years. Still, the burden of proof is on the owner or installer to show that the proper installation procedure and charge controller settings were used.
The quality and durability of modern Lithium Iron Phosphate (LiFePO4) batteries are so good that battery manufacturers use durability as a key selling point.
The high cost of these batteries is easily offset by the numerous benefits versus conventional flooded batteries.