Is It Better to Connect Solar Panels in Series or Parallel?

Connecting solar panels together can be confusing for some people. When connecting multiple solar panels together, you have two options, series or parallel.

There are pros and cons of both of these connection types, so in this blog, I’ll cover them so at the end you’d have an idea about which one will be the best choice, series or parallel?

Generally, it’s better to connect/wire your solar panels in parallel if they have the same voltage but different amps. And connect them in series if they have the same amps but different voltages. If you have the same size of solar panels (Same wattage, volts, amps), then it doesn’t make any difference if you connect them in parallel or series.

if you need quick and straightforward answers about which one would be best for you, scroll all way down to the Summary session.

Series Vs Parallel Connection: Side By Side Test

Here’s a video on series vs parallel connection side-by-side comparison

Disclaimer! This test is based on if you have the same size solar panels connected in series or parallel. To learn more about different size of solar panels keep reading

Difference Between Parallel and Series Connection 

The key difference between parallel and series connections.

  • Parallel connection: The voltage of the solar panel will stay the same but the amps will add up
  • Series connection: The amps of the solar panels will stay the same but the voltage will add up

Now let’s discuss some advantages/disadvantages of having parallel and series connections. And what to do when you have different-sized solar 

Solar Panels In Series

Wiring Diagram

Solar panels connection diagram in series
Solar Panels In Series: Wiring diagram

Series Connection: Advantages

  1. Connecting solar panels in series will be slightly high efficient than in parallel when charging batteries.
  2. Connecting your solar panel in series will make it more efficient due to the low current passing and you don’t have to use thicker gauge wire (which can cost you a lot)
  3. It will be more efficient on raining/cloudy days

Example #1

Batteries required a slightly higher voltage than nominal voltage to get charged. This 12v 100Ah battery requires between 12-14 volts (depending on its state of charge) when charging. 

A 12v 100W solar panel will produce about 18-20 volts under ideal sunlight conditions. Let’s say you have two of them. 

So if you connect them in parallel they would have to perform on their 75% capacity to charge a 12v battery. 

But if you connect them in series they would have to perform only 37% of their capacity to charge the battery 

Example #2

If you’d connect your solar panel in series the voltage will add up but the current (amps) will state the same. 

12v 100w solar panels specs (18v, 5.5 Amps). So connecting two of them would make it a 38v and 5.5 amps output system.

Because of the low output current, there will be less current resistance. As result, it’ll make it more efficient. And you’d not have to spend money on thicker wires.

Series Connection: Disadvantages

  1. If one panel receives a shading the whole system output will go down
  2. You’d need an MPPT charge controller (which is more expensive than PWM)
  3. If one solar panel’s voltage is lower than others, the whole system voltage will drop down. As a result, will cause power loss (watts = amps*volts) 

How Many Solar Panels Can Be Connected To The Series?

You can connect as many solar panels as you want, but one thing to remember is that the total nominal voltage of the solar array should not exceed then the total input nominal voltage limit of your charge controller.

You can use multiple solar charge controllers in one solar array if you want.

Must read: How Many Watts Can A Charge Controller Handle?

Important Disclaimer! all the information above is based on if you have the same size solar panels, if you don’t keep reading.

Solar Panels In Parallel

Wiring Diagram

Solar panels connection diagram in parallel
Solar Panels In parallel: Wiring diagram

Parallel Connection: Advantages

  1. If you have multiple solar panels with the same voltage but different amps. Connecting them in parallel will not cause any power loss.
  2. If the panel receives shading, it will not affect the performance of other panels

Example

 if you have a 200W solar panel with an operating output of 18V and 11.1 Amps. Also a 100W solar panel with an operating output of 18V and 5.5 amps. 

Connecting them in series will add up the amps.

Total amps = 11.1 + 5.5 = 16.6 amps and 18 volts.

The total wattage will be 300 watts (16.6 * 18 = 300 watts)

If you’d connected them in parallel,

The total amps would have been 5.5 and voltage = 18 + 18v (36v)

The total output would have been 198 watts (36 * 5.5 = 198 watts)

Parallel Connection: Disadvantages

  1. The parallel connection will add up the amps, which result will increase the amperage of the overall system. So you’d need thicker wires which are expensive and also there will be some power losses due to the current resistance in the wiring system.
  2. if the amps of one solar panel is lower than other panels, the amperage of the whole system will go down. As a result, will cause power loss (watts = amps*volts) 

How Many Solar Panels Can Be Connected Parallel?

You can connect as many solar panels as you want, A rule of thumb is to remember that the total amp’s output of your solar array shouldn’t exceed 80-100 amps.  

Mixing Different Size Solar Panels: Series vs Parallel

there are two rules when connecting different solar panels.

Rule #1

If you connect parallel, all of the solar panels need to be the same voltage

because if the voltage of one panel is lower than the others, your all solar array voltage will go down. As a result, this will cause a considerable power loss.

For Example

If you have a 12v 100W solar panel with an operating voltage (18v) and operating current (5.5A).

And a 6v 50W solar panel with an operating voltage (9v) and operating current (5.5A). 

In a parallel connection, the voltage of the whole system will go down to 9 volts 

As we know the formula for power is (watts = amps*volts)

9v * 11A (5.5+5.5A) = 99 watts

About 30% power loss will occur in this case.

Rule #2

If you connect Series, all of the solar panels need to be the same amps. 

because if the amps of one panel is lower than the others, your all solar array amperage will go down. As a result, this will cause a considerable power loss.

Related Post: Solar Panel Amps Calculator (Watts to Amps)

Can You Connect Different Size Solar Panels Together?

As long as you follow the above two rules you can connect any size wattage of panels or different size solar panels together.

If you have two different panels with different voltage and amps. You’re typically better going with a parallel connection type. 

I’ve discussed in-depth about connecting multiple solar panels together click here to read.

How to connect the different sizes of solar panels together – Video

This guy has explained very well, which solar panel connection will be good for you.

Summary: Series Vs Parallel Which Is Better For You?

Rooftop With Shading?

If your rooftop receives some shading then go for a parallel connection type

For Cloudy Areas?

if there are most cloudy days go for a series connection type.

Same Amps but Different Voltage?

If you have multiple solar panels with different voltages and the same amps, go for a series type connection

Same Voltage but Different Amps?

If you have multiple solar panels with different amps and the same voltage, go for a parallel type connection

Most Effective Connection Type?

If you have the same sized solar panels then it doesn’t matter if you connect them in series or parallel. But I would suggest going with a series type connection which will be slightly more efficient than a parallel connection in the morning and in the evening

Can I connect different wattage solar panels in series?

Yes, you can connect/hook up solar panels of different wattage together in a series connection. which will add up the voltage of all the solar panels in a result you can get 100% of efficiency if they have the same amps.

Series vs Parallel connection: which is more effective?

series is faster than the parallel connection. it can produce enough voltage to run your charge controller on cloudy days or during sunrise and sunset. so by having a series connection it will give you the benefit that your solar panels can start working as soon as the sunrises in the morning.

How to connect solar panels in series?

in series, Connect the negative of one solar panel to the positive of another solar panel. As result it adds up the voltage of solar panels and the amps will stay the same.

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