Owning a couple of solar panels is a great way to harness the free power of the sun. But you want more power so Is there a way to link portable solar panels together?
Forming a solar array gives you the ability to run more powerful appliances. This is because you can expand your battery bank and of course more power equals faster charging batteries.
In this post I will be looking at the different ways portable solar panels can be linked together. And the various different advantages and disadvantages of linking them.
Is There A Way To Link Portable Solar Panels Together?
“ Yes there is a way to link portable solar panels together. This can be achieved by connecting them in series or parallel but not both. The number of panels you can link together is only limited by the solar charge controller you use. But remember in this post we are talking about portable solar panels not residential. So to avoid confusion Grid-tie residential systems do not require a charge controller. And the solar panels can be linked together in both series and parallel”
How Are Portable Solar Panels Linked In Series?
Portable solar panels can be linked in series. This is achieved by connecting the negative terminal to the positive terminal of the next panel and so on. This is the same way Christmas tree lights are sometimes wired together and are known as a string.
Connecting the panels in series will result in the voltage being cumulative while the current (Amps) remain the same. For a hypothetical example using 2 x 100 watt panels equalling 200w, with a 20 volt and 5 amp output. The portable solar panels linked together in series would produce 40 Volts.
Yet you will notice that if you multiply the total number of volts (40) by the amps (5) it equals 200 watts
Advantages Of Linking Portable Solar Panels In Series
The main advantage being that solar arrays connected in series produce more power output per panel. This means fewer panels are needed to be used to reach the maximum voltage input of your solar controller. This should be calculated using the cumulative open circuit voltage (VOC) of each individual panel.
This translates in savings due to lower wire sizes and cable length, and also in higher efficiency of the PV system (lower electrical losses). (Source; Greentumble.com)
A solar array linked in series has an advantage in low light conditions over a parallel wired array. For instance in the early mornings or late evenings the panels will generate less voltage. So let’s say the voltage output of each panel drops down to 8 Volts. I know it’s random but stay with me
Because the voltage is cumulative in a series array this means the total voltage output would be 16V. This is enough to charge a 12V battery during these times of the day.
Because you are increasing the volts connecting the portable solar panel in series. This configuration can be used to charge higher voltage batteries such as 24V. It is easy to see this using 2 x 12V panels 2 x 12 = 24
Disadvantages Of Linking Portable Solar Panels In Series
There are disadvantages to connecting our 2 x 100 watt panels in series. One of the biggest being that because the panels are connected together with a single wire. If the cable is damaged or severed the whole system will not work.
If there is a problem with the connection of one panel in a series, the entire circuit fails. Meanwhile, one defective panel or loose wire in a parallel circuit will not impact the production of the rest of the solar panels (Source; solarreviews.com)
Shade can seriously affect panels connected in series. If only one solar panel or part of it is shaded the whole solar array will stop gathering sunlight.
If you would like to know more about portable solar panel voltage. You can read about that here:
How Are Portable Solar Panels Linked In Parallel?
Portable solar panels can also be linked in parallel. This is achieved by connecting the positive of one panel to the positive of the next panel. Then the negative of the panel to the negative of the next panel and so on.
Connecting the panels in parallel will result in the amps (current) being cumulative with the volts remaining the same. This is why you cannot use a solar array linked in parallel to charge a 24V battery. Let’s look at how linking in parallel affects our 2 x 100w panels equaling 200w producing 20 volts and 5A.
The panels linked together in parallel would produce 10A (2 x 5A). Again you will notice that if you multiply the total number of amps (10) by the volts (20) it equals 200 watts
So linking in series or parallel and increasing the volts or the amps. Doesn’t affect the total output of the linked panels as both equations equalled 200w
Advantage Of Linking Portable Solar Panels In Parallel
The main advantage of panels connected in parallel is that it is very reliable. Because in this type of array each panel is wired so they are independent from each other. This means if a wire to a panel becomes damaged or broken the other panels will still work.
The same can be said if a panel becomes shaded or damaged. This is because the current is able to pass through the array via different paths.
Disadvantages Of Linking Portable Solar Panels In Parallel
The biggest disadvantage linking portable solar panels in parallel is the voltage always remains the same 12V. This means that if you wanted to use a parallel array to charge a 24V battery you would need 24V panels.
Because you are increasing the amps (current) thicker and shorter wires are required. Plus “Y” branch connectors and more cable is needed.
The higher amps mean that there could be a higher electrical loss in the solar system. This means it is possible that the solar array can lose efficiency.
If you would like to know more about portable solar panel amperage. You can read about that here:
Does Linking Portable Solar Panels Affect The Solar Charge Controller You Should Use?
Not as such just when it comes to using a PWM controller with an array linked in series. There are two types of solar charge controller Pulse Width Modulation (PWM) and Maximum Power Point Tracking (MPPT)
Choosing A Solar Charge Controller With Portable Solar Panels Linked In Series
It is better to use an MPPT controller with a solar array linked in series. This is because of the input voltage limit of the controller which with MPPT is 100V. PWM controllers will have a problem handling the high voltage if the array is over 200w.
If we go back to our 2 x 100w array the first thing we would have to do is find out the VOC of the individual panel. We will use a VOC of 21.6 this is the open circuit voltage of the Renogy Eclipse 12V 100w Suitcase. This means we have a total voltage of 43.2V (21.6 x 2).
Now we need to calculate the size of the solar charge controller required. In this case we will assume a 12v system. This is a very easy calculation. We take the total watts divided by volts and add an extra 25% for environmental factors such as weather conditions.
Total watts are 200 the volts are 12 that equals 16.66 multiplied by 25% is 4.16. Then 16.66 + 4.16 = 20.82 we then round down to the nearest whole number which is 20. So we need a 20A solar charge controller.
We already know that an MPPT charge controller will handle 100V DC input so we are good to go. If you wanted to use a PWM controller. You would have to take the extra step of looking up the controller’s maximum voltage input in it’s specs. To make sure it could handle the total 43.2V.
Choosing A Solar Charge Controller With Portable Solar Panels Linked In Parallel
The procedure for finding the right size controller for our 2 x 100w panels linked in parallel is the same as above. The big difference is that there isn’t an increase in voltage. This means that you could use either an MPPT or PWM 20A controller.
But it is always better to use an MPPT controller because they are more efficient than their PWM cousins.
If you want to take a look at some solar charge controllers you can here;
My Closing Thoughts
Linking portable solar panels can be achieved using series or parallel arrays. Which method you choose to use will ultimately depend on the advantages and disadvantages of each. If reliability is your poison then parallel will be the way forward for you.
If you want to create a higher voltage 24V or 48V system then a series setup would be better for you. At the time of writing some LiFePO4 batteries BMS systems prefer to operate with a 12 volt parallel array. Just thought I would drop that in so you check before spending.
If you would like to take a look around at a 100 watt solar panel. You can do by following this link:
I hope you enjoyed this post and have found it helpful. If you have any questions about linking portable solar panels together in series or parallel. Or want to leave your own personal review, please feel free to leave a comment below.