How To Add Portable Solar Panels To Your Existing System
Guides, Tips and Reviews
By Admin | 24 June 2022 | 0 Comments

How To Add Portable Solar Panels To Your Existing System

Almost all RVers set up a solar system on their RVs. But when you park RVs in shade, the roof-mounted solar panels would be almost useless. For some RV beginners and small camper owners, most of them use a basic 12 volt system. It cant generate enough power over the winter. So, adding portable solar panels to the existing solar system becomes a trend. The portable panels can better position toward the sun and add solar power to the battery bank. Then, how to connect this to the existing system? 
It depends on the conditions of your existing system and your new panels.

With Separate Charge Controller

If the portable solar panel has its separate charge controller, the best option is to attach the portable panel with its own charge controller directly to the battery bank instead of messing with your existing system. You can parallel both new and existing charge controllers to the battery bank. Its like using two hoses to fill the pool.
Two 100w portable solar panels in parallel are a good choice. The charge controller would preferably be an MPPT controller and not a PWM controller. The controller doesn't have to be attached to the trailer. It can be placed free standing literally anywhere. Just make sure it is protected from the rain if you are not at the campsite.
The MPPT charge controller would transfer more power than the PWM controller. According to the test data, it transfers 20% to 30% more power in cold temperatures, and 10% to 20% more power in hot temperatures.
Note that 
1. It is best to only combine similar solar panels on one controller. Different wattage, amps, and volts default to the lowest output in amps or volts depending on how you set the system up.
2. All controllers have specs for max input voltage and amperage. Make sure your panel output is within range.
If you want one battery monitor to sense and measure the total power in and out, just wire the portable system negative to the shunt (if you have that type of monitor) where everything else is.

Has No Separate Controller

If the portable panel has no controller, check if your controller is able to run a second panel or not.
Usually, the roof-mounted panels are wired in parallel. If the VoC voltage ratings of your roof-mounted panels and the 100w portable solar panels are about the same (around 20-22 volt), and if the controller is able to handle the additional amps, then you can simply wire the portable panel in parallel with the existing panels. If you want to mix and match different panels (roof plus portable), those panels need to be properly matched.
If your existing charge controller is PWM, the Vmp voltage ratings of your existing solar panels and your new portable solar panels should be very similar. And the total amp amount of those panels in parallel should be within the amp capacity of the controller. Short and thick wires are good to use to avoid voltage drop.
If your existing panels are portable, then, it comes to the topic of wiring them in series or parallel. Wiring in series would get higher voltage. Its good for a cloudy day. And you can use longer and thinner wires. But you need to use an MPPT charge controller. Some parts of the panels under shade would affect the total output power. Wiring in parallel can get higher amps with low voltage. It saves your money because you can use a PWM charge controller. For details, you can read the article Connecting Solar Panels In Series Or Parallel.
No matter in which method, there are three things you need to pay attention to. First, you should know your requirement operate voltage. Second, the total output voltage of the solar panels should be larger than the voltage of the battery. Finally, its better if the main specification of each solar panel is very similar.


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