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Connecting Solar Panels Together For Increased Power

How to Connect Solar Panels Together

Connecting solar panels together is a simple and effective way of increasing your solar power capabilities. Going green is a great idea, and as the sun is our ultimate power source, it makes sense to utilize this energy to power our homes. As solar power becomes more accessible, more and more homeowners are buying photovoltaic solar panels. However, these solar panels can be very costly so buying them over time helps to spread the cost. But the problem then becomes how do we connect these extra solar panels together to increase the voltage and power output of what's already there.

The trick here when connecting solar panels together is to choose a connection method that is going to give you the most energy efficiency configuration for your particular requirements. Connecting solar panels together can seem like a daunting task when you first start to look at how it should be done. Wiring solar panels together to make larger arrays is an often overlooked, yet completely essential part of a well designed solar power system.

There are three basic but very different ways of connecting solar panels together and each connection method is designed for a specific purpose, for example, to produce more voltage or more current. Solar panels can be wired in a series or parallel combination to increase the voltage or amperage respectively, or they can be wired together in both series and parallel to increase both the voltage and current output. As long as you understand the basic principles of how each of these wiring methods works, you can easily decide on how to wire your own panels together. After all connecting solar panels together correctly can greatly improve the efficiency of your solar system.

Connecting Solar Panels in Series

The first method we will look at for connecting solar panels together is what's known as "Series Wiring". Connecting solar panels together in series is used to increase the total system voltage. Solar panels in series are generally used when you have a grid connected inverter or charge controller that requires 24 volts or more. To series wire the panels together you connect the positive terminal to the negative terminal of each panel until you are left with a single positive and negative connection.

Solar panels in series add up or sum the voltages produced by each individual panel, giving the total output voltage of the array as shown.

Solar Panels in Series of Same Characteristics

solar panels in series of same characteristics

In this method ALL the solar panels are of the same type and power rating. The total voltage output becomes the sum of the voltage output of each panel. Using the same three 6 volt, 3.0 amp panels as above, we can see that when they are connected together in series, the array produces 18 volts (6 + 6 + 6) at 3.0 amps, or 54 watts (volts x amps).

Now lets look at connecting solar panels in series with different nominal voltages but with identical current ratings.

Solar Panels in Series of Different Voltages

solar panels in series with different voltages

In this method all the solar panels are of different types and power rating but have a common current rating. When they are connected together in series, the array produces 21 volts at 3.0 amps, or 63 watts. Again the amperage remains the same at 3.0 amps but the voltage output jumps to 21 volts (5 + 7 + 9) .

Finally, lets look at connecting solar panels in series with completely different nominal voltages and different current ratings.

Solar Panels in Series of Different Currents

solar panels in series with different currents

In this method all the solar panels are of different types and power rating. The individual panel voltages will add together as before, but this time the amperage will be limited to the value of the lowest panel in the series string, in this case 1 amp. Then the array will produce 19 volts (3 + 7 + 9) at 1.0 amp only, or only 19 watts out of a possible 69 watts available reducing the arrays efficiency.

We can see that the solar panel rated at 9 volts, 5 amps, will only use one fifth or 20% of its maximum current potential reducing its efficiency and wasting money on the purchase of this solar panel. Connecting solar panels in series with different current ratings should only be used provisionally, as the solar panel with the lowest rated current determines the current output of the whole array.

Connecting Solar Panels in Parallel

The next method we will look at of connecting solar panels together is what's known as "Parallel Wiring". Connecting solar panels together in parallel is used to boost the total system current and is the reverse of the series connection. By parallel wiring panels you connect all the positive terminals together (positive to positive) and all of the negative terminals together (negative to negative) until you are left with a single positive and negative connection to attach to your regulator and batteries.

When you connect solar panels together in parallel, the total voltage output remains the same as it would for a single panel, but the output current becomes the sum of the output of each panel as shown.

Solar Panels in Parallel of Same Characteristics

solar panels in parallel of same characteristics

In this method ALL the solar panels are of the same type and power rating. Using the same three 6 volt, 3.0 amp panels as above, the total output of the panels, when connected together in parallel, the voltage output would remain the same at 6 volts, but the amperage would increase to 9.0 amps (3 + 3 + 3), or 54 watts.

But what if our newly acquired solar panels are non-identical, how will this affect the other panels. We have seen that the currents add together, so no real problem there, just as long as the panel voltages are the same and the output voltage remains constant. Lets look at connecting solar panels in parallel with different nominal voltages and different current ratings.

Solar Panels in Parallel with Different Voltages and Currents

solar panels in parallel with different voltages and currents

Here the parallel currents add up as before but the voltage adjusts to the lowest value, in this case 3 volts. Solar panels must have the same output voltage to be useful in parallel. If one panel has a higher voltage it will supply the load current to the degree that its output voltage drops to that of the lower voltage panel.

We can see that the solar panel rated at 9 volts, 5 amps, will only operate at a maximum voltage of 3 volts as its operation is being influenced by the smaller panel, reducing its efficiency and wasting money on the purchase of this higher power solar panel. Connecting solar panels in parallel with different voltage ratings is not recommended as the solar panel with the lowest rated voltage determines the voltage output of the whole array.

Then when connecting solar panels together in parallel it is important that they ALL have the same nominal voltage value, but it is not necessary that they have the same ampere value.

Connecting solar panels together to form bigger arrays is not all that complicated. How many series or parallel strings of panels you make up per array depends on what amount of voltage and current you are aiming for. If you are designing a 12 volt battery charging system than parallel wiring is perfect. If you are looking at a higher voltage grid connected system, than you're probably going to want to go with a series or series-parallel combination depending on the number of solar panels you have.

But for a simple reference in regards to how to connect solar panels together in either parallel or series wiring configurations, just remember that parallel wiring = more amperes, and series wiring = more voltage, and with the right type and combination of solar panels you can power just about any electrical device you may have in your home.

For more information about Connecting Solar Panels Together in either series or parallel combinations, or to obtain more information about the different types of solar panels available, or to explore the advantages and disadvantages of using solar power in your home, then Click Herealt to order your copy from Amazon today and learn more about designing, wiring and installing photovoltaic solar electric systems in your home.

Some high quality solar panels you may be interested in which can be connected together and used in solar arrays.

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Comments (3)

  • avatar

    Hello,
    I am a newbie to this site and have been reading stuff for days. Thank you so much for all the great info.:)

    I have a 24v system, 8 T105's in a series/parallel configuration, 2800 watt Magnum inverter at a remote camp off grid.

    I have 6 solar panels now and will be adding 6 more soon as the are on the way now. The 6 panels are configured (2 panels in series, 3 strings paralleled) as follows

    2 Kyocera 120 watt in series with a Voc 21.5v, Vmp 16.9v, Isc 7.45a, Imp 7.1a these are paralleled with 2 strings of

    2 DM solar 145 watt in series with a Voc 21.7v?, Vmp 18.0v, Isc 8.48a?, Imp 8.0a (I am sure of the Vmp & Imp, guessing on the Voc & Isc)

    Based on what I have read here, connecting panels in series you look a the difference in current and when connecting in parallel, you look at voltage. The above configuration seemed to yield the most out of the panels. If I add 6 more DM solar 145 watt panels and configure the 6 additional panels as 3 more strings like above, I will have a current of 47 - 48 amps. If I go this way I will have to change my 70 foot run of #6 copper to something bigger which I am OK with if it makes sense. If I do could I use a #2 URD cable as it has 4 conductors (3 - #2's & 1 - #4) so I could do a parallel thing. I am planning on buying the MidNite Classic 150 but could buy the 200 or 250 if it makes sense to you guys that I instead put more panels in series. I didn't know how to configure because if I put 5 DM solar 145's and 1 Kyocera 120 in a string then wouldn't all panels in the string be capped at 7.1 amps which I would lose about 80 watts per string?

    I greatly appreciate your thoughts ;)
    Scott

  • avatar

    A really nice, well explained article.

    Many thanks.

  • Thank you for the kind comment, glad you like it.

    Connecting together solar panels can be difficult if they are not of the same voltage and current ratings. Many people think that if they have a panel of 50W and one of 200W then they will have a 250W system but as shown above this is not always the case as differences in voltages and current ratings reduce an arrays efficiency. ;)