In this article, David answers a question from a reader about a portable solar blanket to capture the energy from the sun.
Hello 12V Guru,
We need some advice please.
We have a 2018 Jayco Silverline Outback with one 160W solar panel on the roof. We have had Jayco install an Anderson plug to run through the JHub, allowing us to plug in and monitor another solar panel or mat.
Could you please advise whether we can use the same size 160W solar panel or if a larger solar mat would be more suitable?
Thanks,
Neil Death
Maryborough, Qld
Hi Neil,
Thanks for your question. Having more power (stored or generated) is definitely popular at the moment as many RVers upgrade their vans. The advantage of adding additional solar that is not permanently fixed to the roof — such as a portable blanket or mat — is that it allows solar generation when the rooftop panels may be shaded. A solar blanket or foldable solar setup that plugs into an Anderson-style connector on the exterior of the van allows you to track the sun in direction and angle.
The BMPRO J35 Power Management System that powers your van has a proprietary charging algorithm which can handle additional power wired in parallel directly to the solar input on the unit. Wiring directly to the positive and negative of the J35 means it has been installed in parallel, and therefore the biggest consideration that you will need to factor in is the voltage range.
You just need to ensure that both the fixed and portable solar panels have relatively similar voltage ranges. Otherwise, the panel that has the lower voltage will drag the other panel down to the lower voltage and it may no longer operate as its maximum. The extra potential goes unused. In the standard 12V space most panels will be relatively similar so it should not be difficult to purchase. Ensure that the connectors and wiring are sufficient to manage this setup. It is relatively simple but important to regularly check the setup to ensure tight connections, dust free connectors and no damage to wiring.
From a monitoring perspective, yes, the JHub monitor will be able to show the combined solar power generated. However, keep in mind that it will not be able to identify that there are two separate solar strings, as both are wired to the same solar input. The combined total of amps will be shown on the solar section of the display.
The J35 can produce up to 27A of solar at maximum efficiency, so adding an extra solar panel will work well. The 160W panel at a nominal voltage of 12V means that it would generate up to 13A of current. Therefore, a portable solar panel of approximately 150W or less would be suitable to add to your system. You could go larger in size to allow for inefficiencies of solar production such as the panel’s angle to the sun and shading.
If your panels are not closely matched in voltage, consider a separate solar controller and wire directly to the battery. However, the disadvantage of this setup is that while you could tweak another 5–10 per cent of power, you would need to consider a current monitoring device that can share the details with the J35 of this additional power that is generated. This is critical so that the information can be displayed on your monitor, allowing you to position the portable solar panels in their most efficient location. It also means that the power management system (PMS) understands the energy stored in the battery. If the PMS can’t ‘see’ this additional energy it will not be able to charge the battery effectively. You could use the BC300 shunt, which is suitable in this scenario. However, this is an additional cost.
The setup should be relatively simple, and with this additional solar generation, you should find that your batteries are fully charged to maximise your travels.
Safe travels,
12V Guru
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