How To Connect Two Solar Panels To One Battery | Guide

ByWarren Brown Updated on:
How To Connect Two Solar Panels To One Battery

So, you have bought a solar kit or portable solar panels and want to connect them to a battery, but are a little confused? don’t worry, it is very simple to connect two solar panels to one controller and battery.

In this article, we will explain to you how to connect two solar panels to one battery. If you have any doubts regarding the steps, you can let us know in the comments section below. 


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Connecting Two Solar Panels To One Battery

Connecting Two Solar Panels To One Battery

Step 1: Connect Your Battery To The Controller

The primary step is to connect your battery to the charge controller (MPPT or PWM).

You must do this action first. If you connect the solar panels to the charge controller, you might run the risk of destroying the charge controller while doing so. (If you are searching for a good solar charge controller, you might want to read our article on the best solar charge controller to choose a good charge controller)

Wire density depends on the existing that your charge controller is going to send to the batteries. For instance, the Renogy Rover 20A provides 20 amps to the battery. You require wires that can bring 20Amps or more and utilize a 20Amp fuse on the wire. Only fuse the positive wire.

If you are using a flexible copper wire, you require this AWG12 wire with this fuse. Place the fuse as near the battery terminals as possible.


You ought to wind up with a setup like this:

Step 2: Connect Your Solar Panels

In this action, you are going to link your two solar panels together in series or parallel connection as per your choice, you can read our series vs parallel connection guide that will help you to make your decision easy about the what kind of connection to go for.

This can be performed in series or parallel. Connecting your 2 panels in series will build up the voltage, while parallel will build up the current. If you wire in series, you require a smaller sized size of wire than parallel. Continue reading to find out “how to wire solar panels in series”.


The fuse ranking is defined in the solar panel datasheet or on the sticker label at the back of the panel. You can use an inline MC4 port fuse.

Step 3: Connect The 2 Solar Panels To The Charge Controller

The wire from the solar panel will be too short to run to your charge controller. Use this wire to extend it so it can reach your charge controller. Most of the time, you are going to utilize the series connection. So we will continue the example with the series connection.

Position your charge controller as close to your batteries as possible. Put your charge controller as near to the two solar panels as possible to lessen wire losses.

If you have a remaining wire from the solar panels to the charge controller, then shorten them to decrease losses.

Your DIY planetary system will now look like this:

Step 4: Connect The Loads

Connect the loads

If you have little DC loads, you can connect them to the load terminal on the charge controller. If you want to utilize an inverter, I advise using the battery terminals. See the following diagram as an example.

The size of the wires will depend upon the present that will go through the wires. If the inverter uses 100 amps of the current, you require to size your cable and merges for that existing. 

Once completed, you can use the solar panels to heat you greenhouse or run a refrigerator, these are few examples of how solar panels are applicable.

Conclusion

Linking 2 solar panels to one charge controller and one battery is not that difficult to do. You require to follow these instructions on the page and utilize the circuit diagrams I have shown you. If you have questions, make sure to send me an e-mail or leave a remark below.

FAQs

You might think we have already answered this. Nevertheless, there’s one consideration. To power a dual battery system, you’ll require to connect the panels in parallel.

Linking 2 solar panels in parallel. Link the negatives to the negatives and positives to the positives. To get maximum output, you would require both panels to have the same optimum voltage. For example, the 115W SunPower solar panel has the following scores:

  • Optimum ranked voltage = 19.8 V.
  • Optimum ranked existing = 5.8 A.
  • Optimum rated power = Volts x Existing = 19.8 x 5.8 = 114.8 W.
  • Connecting two of these blankets in parallel will give you:
  • Optimum rated power = 2 x 19.8 x 5.8 = 229.6 W.

Nevertheless, if you have two panels with various output scores, the optimum voltage for the system is identified by the panel with the most affordable optimum ranked voltage.

Baffled? Let’s take a look at what takes place when we connect our solar panel and solar blanket.

Panel:

  • Optimum ranked voltage = 18.0 V.
  • Optimum rated existing = 11.1 A.

Blanket:

  • Maximum rated voltage = 19.8 V.
  • Optimum rated existing = 5.8 A.

Connecting them in parallel will give you:

Maximum rated power = (18.0 x 11.1) + (18.0 x 5.8) = 304.2 W.

The output of the solar blankets will therefore be de-rated to (18.0 x 5.8 =-RRB- 104.4 W or by 10%.

In our case, it’s not a big offer.

It’s more when you have a bank of panels ( LG or Sunpower Panels) linked in parallel, for instance, 6 on the roof of a motorhome. Then you start to lose significant capability.

You can link them in parallel, offering your battery management system can deal with the maximum input power. How do you calculate optimum input power? See “Can you link two solar panels to one battery?” above.

Figure out what gadgets you wish to run. For instance:

  • A refrigerator (how many solar panel to power refrigerator) draws 7A and runs for 20% of the day (24 hours). So average existing draw in one hour is 7 x 0.2 = 1.4 Ah.
  • An inverter draws 45A for 5% of the day. So average existing attract one hour is 45 x 0.05 = 2.25 Ah.
  • USB ports and LED lights draw 5A for 20% of the day. So typical present draw is 5 x 0.2 = 1.0 Ah.
  • The water pump draws 7.5 A for 5% of the day. The average current draw is therefore 7.5 x 0.05 = 0.375 Ah.

Add them together: ( 1.4 + 2.25 + 1.0 + 0.375) = 5.0 Ah. Let’s round it to 6Ah.

What does this indicate? Well, in 24 hours you.

I will use 24 x 6 = 144Ah. State 150Ah.

Your solar panels must be capable of providing this. Let’s size your solar panels:

  • Assume an optimum of 6 sunshine hours.
  • So in 6 hours, they must supply 150Ah to the battery or 25A (150/6).
  • If we assume that the solar panels supply 12V, at 25A, you will require a solar panel capable of 300W (25×12) 
  • Enable at least 10% additional capability:
  • So, you would require 300 x 1.1 = 330W of solar panels.
  • Your probable match will be 350W.

Deep cycle batteries do not like to drop below 50% capability (Lithium batteries can go much lower without damage).

You use 150Ah in 24 hr. However, you can’t discharge listed below 50%. So you require 300Ah.

The solar panels supply 150Ah in 24 hr. They will recharge your battery to 100% every day (assuming 6 hours of available sunshine).

In Summary: You do not simply match the solar panel to the battery. You need to understand the loads on the battery, size the battery to match the load and after that size the solar panels to match both the load and the battery. I informed you the answer wasn’t basic!

Yes! Never link a solar panel directly to a battery. It requires a regulator in between the panel and the battery.

The regulator will either be mounted on the back of the solar panel or within a battery management system (BMS). The regulator controls (funny that!) the voltage from the solar panel and safeguards the battery from over-voltage.

Warren has always been fascinated with renewable energy and has managed to live in a house that is 100% powered by Solar energy. With the help of his website, he aims to write content that can help the general public convert to renewable energy and save on costly electricity costs, while also helping the Earth stay alive.

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14 Comments

  1. Hi!am antony happy to know all this ur work is good.but I have one question is it a must panel to have equall watts?

    Reply

    1. No, you can use different wattage so long all take equal voltage. There are some that require 24volt battery and others 12volts battery.

      Reply

    2. I bought 2 solar panels of 190 watts and a tubular battery of 220ah. My controller is a small 50A even though I doubt if it’s capable of 50A capacity.
      I want to connect in the panels in parallel. Please I want to ask assuming this controller’s caoacity is 30A would this controller not be damaged?

      Reply

  6. Well done reguest of drawing of six solar panels connected in series with 2 Barry’s 0f 200ah together with hybrid inverter

    Reply

  8. How do l calculate the total power in watts of 12pieces of 380watts solar panels connected two in a series to form 6 strings & 6 strings connected in a parallel.

    Reply

  9. A couple of years ago I bought a portable solar panel suitcase for my rv. The panel has a built-in controller. Last year I bought an rv that already has a roof mounted solar panel with a controller mounted inside the rv. I am wondering if I can use the portable system along with the roof mounted system? Can I just clamp the portable system onto the battery terminals along with the roof mounted solar system?

    Reply

    1. Hi that’s what I have done

      I have roof panel 350w portable 100w panel
      They are both connected with controller to battery
      .seems to work ok

      Reply

  10. hi i have just purchaced the kit shown,should i wire it the same as youre diagram above ?
    thank you great content
    kind regards

    Reply

  11. Hi MR l have got two 100 watts solars they are the same.. but l connected them in parallel. The problem now comes after some days charging the 12 v battery.. when solar wires started heating..just when connected to the battery. Please am confused what would be the cause of that problem.. may you help me with a good solution to this problem.

    Reply

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