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

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.

Here we go:

Materials & Tools

Materials

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

Tools

  • Screwdriver

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?

On to the final step!

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 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

1. 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.

2. 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.

3. 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.

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Alex Beale
Alex Beale
Hi, I'm Alex. I started Footprint Hero to help people reduce their environmental impact. My current obsession is DIY solar power projects, which I've been building since 2020.

25 thoughts on “Connect Solar Panel to Charge Controller: 3 Steps (w/ Videos)”

      1. so my charge controller isn’t showing load but everything is connected. however from the battery I’ve connected an inverter. and on my charge controller there are holes you can put cables feeding to the lights (load i assume). so I’m thinking is i connect my inverter to that remaining outlet will things not go south here. help.

    1. Thank you so much. This is the first explanation I’ve found in 2 mths that really explains exactly how to do the correct way. And if there’s any issues too. You are a hero in my book. This will be so easy to do know
      I have a issue we’re the solar will not turn on. I think you just explained it. Very much appreciated your so great. Can’t thank you enough for this. Hope you have a great day
      You seem to be the only one that really cares out there for us knewbies. Can’t thank you enough
      Vicky

        1. The PV terminals are where you connect the solar panel. PV stands for “photovoltaic” which is basically another way of referring to solar energy. Added a note in the post clarifying this.

  1. Hello thank you for the clear information! I plan on running a similar rig but wondered how best to direct the cables off/over my roof down the side of a wall for occasional battery charging. Do I need to shield the cables in a housing or elevate the cables off the roof itself?

    1. You’re welcome! Good question, but I won’t be of much help unfortunately… So far I’ve only built ground- and wall-mounted installations so I haven’t looked much into this topic yet. There are “entry glands” like the SolaDeck for getting the wiring from roof to attic, but that’s about the extent of my knowledge here. (I’m assuming you’re mounting your panel to the roof of your house.)

      Though if you only need your solar setup for occasional battery charging then maybe you don’t need to roof-mount your panel(s)? Maybe just keep it in storage until you need it? That could save you time/money on installation.

    1. No, if it has the charge controller built in you should be able to connect it directly to the battery. I’d double check the manual that came with it, there’s probably an “Installation” section with instructions.

  2. I have 3 solar panel 100 watts 12v. each and 30 amps solar charger control how many ampshour battery should i use for 2kw inverter .?

    1. Thanks for your question, Victoriano. Unfortunately — and despite the fact that I love discussing anything and everything solar! — because I’m so busy at the moment, I’m currently not doing any one-on-one advising. Thanks again and good luck with your solar power system!

    2. The power capability of the inverter has only a relative link with the battery capacity.
      Why? Look here. Let’s assume that you have a 12V battery with 60Ah capacity.
      Well, the correct question is “in how many hours I will discharge the battery? ” 🙂
      To get an answer, let’s assume first that the battery could be totally drained (discharged); this is not practically true, but for simplicity, let’s just consider it for the moment.
      Assuming also that you will use a constant load on the battery ( for example, a 12V /12W LED stripe), then you may calculate the total time for draining the battery in this way:
      1) the LED stripe will pull a current I = P/U = 12W/12V = 1A .
      2) the battery has a 60Ah capacity; so, it will be drained in an interval of (60Ah/1A) = 60 hours .
      NOTE: Don’t forget that the “Ah” means “Amperes * hour” . This come from the energy formula that is Energy = Voltage * Current_intensity * time = U * I * t .

      Returning to your question, you will notice now that you can use your 2kW inverter without any problem either with a 60Ah battery, or with a small 7Ah battery. The difference is given by the time interval in which the battery will be discharged.
      At this point, I must mention that there is no battery that could be totally discharghed (without permanent damage).
      For example, a standard auto lead-acid battery, will not support more than a maximum 50% of their capacity. Usually, the battery voltage is monitored by an electronic system (“watch-dog”) and when it will reach a level of 10.5V-11V, the load will be disconnected.
      The AGM gel batteries supports an heavier regime, the best are the “deep-cycle” batteries, or the modern Lithium batteries – most of them could be discharged safely to 80% of their capacity ( depth of discharge = DoD) .

      A practical example.
      ——————–
      You have a 2kW inverter. For safety reasons, you will not load it 100%, so you will use only 1.5kW from it.
      Let’s assume that you are using a couple of 12V/100Ah batteries (a total of 24V/100Ah) and that you will run a constant load that pulls 1500W (at 220Vac) from the inverter .
      A simple practical calculus:
      —————————
      I1 = P1/U1 = 1500W/220V = 6.81A (that is the total current intensity when you pull 1500W at 220V)
      Now, let’s convert the 1500W to the current pulled from the 24V battery system.
      I2 = P1/U2 = 1500W/24V = 62.5A
      The batteries are connected in series, so the current drawn will be the same on each 12V battery.
      So, you will totally drain the batteries in an interval of 100Ah/62.5A = 1.6h = 96 min .
      But you know that you cannot drain the batteries, you must discharge them at their recommended DoD ; almost every inverter has a watch-dog for battery discharge, so you will not totally drain the battery.
      For the situation exemplified above, and a 80% DoD, well, you will reach the discharge level at an approximately 80% of the calculated 96 min. That means cca 75 minutes.

      Please note that the above calculations doesn’t include the the current consumed by the inverter itself, as well as the losses that still occur in such a system. It is most likely that you could count on a realistic smaller discharge time – somewhere between 60 to 70 minutes.

      I hope that my explanations will be useful, maybe also for others.

  3. I should’ve read this first before connecting the panel to the charge controller…without first connecting it to a battery. I think I destroyed the charge controller.

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