Switching to portable solar panels?

[medora]

Hi all! We have a 17B with 300w of panels up top. I recently got an EcoFlow unit with 2 220 bifacial portable panels and am curious if there’s a way to set up a switch of sorts that would allow me to use the portable panels when they’re beneficial, bypassing the panels on top - something that wouldn’t require unplugging the cables on top of the camper and plugging in the portables every time I wanted to use the them. Anyone got such a system in place?

Thanks!!

 

[Kingfisher]

What specific Ecoflow unit did you get?

 

[medora]

The Ecoflow Delta Pro. I know we could basically plug in to it and use the extra solar through it - but it's extremely heavy and we may not bring it along on shorter trips. Thus the question.

 

[John in Santa Cruz]

you can connect your two external panels in series with an MPPT controller, and you'd have ~ 12 amps at around 36V solar power, which the MPPT controller would turn into about 30A at 14V to charge your lithium batts, this would add to your rooftop solar. with the same setup you could just deploy one of your 220W panels, as the MPPT will automatically adapt to the incoming voltage. I'm a fan of the Victron SmartSolar MPPT series, for this you'd probably want the 100/50 ... you could install this inside your trailer near your batteries and leave it connected, you'd need some sort of solar power connector externally along with suitable cable to connect to the solar panels.

 

[Ron in BC]

You could us a dual position battery switch. It would allow you to select input from one or the other source or both or all off.

Ron

 

[GinoandLinda]

I’d like to know more about your use case. How would you like to see your desired setup work and when would you use it?

 

[medora]

I’d like to know more about your use case. How would you like to see your desired setup work and when would you use it?

Basically, when we're camping in a spot where the rooftop solar gets enough light, I'd like to go with those panels. When not, it'd be great to be able to use the portables. As I understand it I can't use ALL the panels because they're different wattages (on top, 100W; the portables are 220 bificials). Wrong?

You could us a dual position battery switch. It would allow you to select input from one or the other source or both or all off.

Ron

Per this - I don't know where I'd be plugging in the portable panels, that's the issue (short unplugging what's on the roof and then plugging in the portables, which ain't gonna happen -- educate me! I'm a quick learner and can likely set this up if I have an idea what I need to do.

 

[GinoandLinda]

There’s no reason you can’t have your portable panels feeding the batteries in addition to your rooftop panels. We do this with our portable 130w panel that has its own controller. We have a pigtail on our battery bank and plug the portable into it. I guess you could go through the trouble of using the Zamp port and rewire it to its own controller but, whew, I get tired just thinking of doing that.

 

[SRS]

If your batteries are still on the rear bumper, The easiest solution is to use alligator clips and connect the panels directly to the battery post. You would need a solar controller to control the charging based on the chemistry of your batteries. You could also install a Zamp port (SAE port) or Anderson power pole. Below are examples:

https://www.amazon.com/SAE-Connector-Weatherproof-Universal-Generator/dp/B0DL29QPJM/

https://www.amazon.com/Connectors-Connector-PP15-Waterproofwith-Replacement/dp/B0DXKHRFLK/

Alligator clips would be the simple way to go especially if you don't us the portable very often. Whichever way you go, it's best to have the solar controller as close to the battery bank as possible to reduce electrical resistance with long extension cables. Hope that helps.

 

[Kingfish]

So there's not a problem with charging the battery from two sources (rooftop and portable with its own controller) at the same time?

 

[GinoandLinda]

Nope, as long as the controllers are operating correctly. If you do use alligator clips or a wired pigtail, make sure the leads going to the battery bank have a fuse.

 

[dosby]

Another option is to have a small inverter and plug in external solar power to the shore 110V input. Energy loss % but less mess.

 

[John in Santa Cruz]

Another option is to have a small inverter and plug in external solar power to the shore 110V input. Energy loss % but less mess.

that won't work well... if the solar panel isn't making enough power to run the inverter at the full power drain of your voltage converter, it all shuts down. Mine pulls about 700W or 800W AC to make 50A charging current for my lithiums.

 

[Mike G]

I have a small panel on the roof, and also a small portable with waterproof controller that I've rigged to plug into the trailer's 7-pin cord. No problem using both at the same time. But yeah, when I was first looking at all of this, I had the same question.

 

[alanmalk]

As I understand it I can't use ALL the panels because they're different wattages (on top, 100W; the portables are 220 bificials). Wrong?

Wrong.

If the panels come with a simple "back flow preventer" or "blocking" diode then you can mix any wattage with any other wattage. You can also mix any voltage panel with any other - but that usually would be wasting your money if the panel voltages differs by more than a couple of Volts - but the only harm would be to your wallet. I am using a 200 W portable panel, a 150 W portable along with my roof 160 W panel and obtaining all the power I would expect.

I guess it is conceivable that some panels could come without a blocking diode but hard to imagine. And easy enough to add one if necessary.

Don't confuse "blocking" diodes with "bypass" diodes that fancier panels use for shade tolerance. Those require multiple diodes per panel and the diodes behave in a different manner. It is hard to imagine that the builder wouldn't add one additional blocking diode.

One case where you might not want to add 100 W and 220 W together is if the regulator is not rated for 320 W input. I don't recall exactly what the input limits are on my 2015 '21C are, but I have no concerns using all three of my panels at once in the winter, and have no need for 3 panels in summer.

 

[alanmalk]

that won't work well...

Hmmm,
Why does that remind me of the time I accidentally powered up my inverter while it was connected to the converter? Is it the memory of the inverter whine or the converter pulsating? Oh - it was the ground loop... (And I'm sure I am overlooking one or two more potentially damaging faults.)

 

[Thrak]

I have this Go Power 130W suitcase panel that I intend to use in addition to the 180W on the roof. It has it's own 10 AMP controller.

I attach it directly to the batteries using pigtail. The normal trailer plug that goes into the port on the truck plugs right into this unit.

I have a 30' cord that allows placement wherever I like. We used this setup with our teardrop. It "should" work fine in conjunction with the roof unit that goes through the controller in the E19 as it connects directly to the batteries.

 

[shocksll]

I just rewired my sae external solar port from going to the solar controller to going to the battery. This enables me to have a separate controller and panels for the external connection while my rooftop can also provide charge to the batteries.

 

[BobG-ESC]

I just rewired my sae external solar port from going to the solar controller to going to the battery.

It looks like you have a shunt to keep track of the current flow to the battery. I assume you rewired the external solar port to connect to a new solar controller that has the negative conductor connected to the upstream side of the shunt and not directly to the battery?

 

[shocksll]

That is correct, i connected it to the psu which is upstream from the shunt. The shunt is last before batteries.