Adding Solar to 21RBS

[Merlin]

tt2retire, This complexity and cost would only be needed if the roof panel and portable panel are different in output. If they are the same, you can parallel them at a combiner box before the charge controller. There is no need for each panel to have a CC in that case.

[GrampaKilt]

On appearances alone, your setup looks very, very well done. GK

[tt2retire]

I agree it would be less costly with one CC, but I have three different scenarios I'm taking care of for this solar installation.

1) 1 or 2 portable panels only (120 and/or 50W)
2) 3 or 4 roof panels only(100 or 110W)
3) both roof and portable panels

With one CC I could put in a bunch of extra switches and wiring to cover those scenarios, but then I would have to get to the switches which is harder to do given the location and protection (ie door) of the components. I would also like the use of all the solar panels to be really easy in case my LSW or kids might want to help out (who am I kidding here). So for $118 for the 2nd smaller CC, I'm thinking it would at least allow me a little more free relaxing beer sipping time while camping :-)

[tt2retire]

Finished the pass through storage installation except for adding the doors to cover it up. Next phase is to run the wires to the roof and install the three roof solar panels  (hopefully before July's month long trip!). Due to the potential temperature difference between the CCs and the batteries, I mounted a bluetooth temp/voltage sensor to the batteries on the tongue. All my components are from Victron, so they network together except for the BMV 700 battery monitor which I bought before they had the networking capabilities. Seems to be working really well in my backyard testing so far.

[Merlin]

Finished the pass through storage installation except for adding the doors to cover it up. Next phase is to run the wires to the roof and install the three roof solar panels  (hopefully before July's month long trip!). Due to the potential temperature difference between the CCs and the batteries, I mounted a bluetooth temp/voltage sensor to the batteries on the tongue. All my components are from Victron, so they network together except for the BMV 700 battery monitor which I bought before they had the networking capabilities. Seems to be working really well in my backyard testing so far.

Nice job! That really looks nice. And nothing blew up when you plugged it all in! I assume you have lead-acid batteries and not lithium?

[nhlakes]

@tt2retire Nice work.  Curious as to why did you mounted the Victron BMV in the storage department.  Do you have the bluetooth dongle and just use the app?

[tt2retire]

Thanks for the comments!

I was a bit worried about something blowing up, so I made sure I could shut off the entire new system with just one switchable circuit breaker that is independent from my battery disconnect switch.

Yes, I have two lead-acid batteries (Trojan Solar T105-RE 6V 229 AH). I bought them back in 2018 so they should hopefully last another 6+ years. When I replace them it certainly will be with lithium. I figure at that time I might fill up the other empty area of the pass through storage area with an inverter if it seems necessary. We usually don't carry any extra equipment that needs 120AC.

So I bought my BMV 700 along with the bluetooth dongle back in 2016 just after our first few trips in the trailer. I really struggled with the original single 12V battery on our 13 day Glacier trip. Since the trailer was new I didn't have the confidence to make a bunch of holes so I could mount the monitor display inside. I stuffed the monitor/dongle/extra wire inside a ziplock bag and zip tied it to the top of my pass through storage. I got so use to using the phone app that I never thought much about looking at the display. Now that I have four Victron components that I can monitor through bluetooth, I don't think I'll ever switch to a dedicated display. If I had to do it over again, I would buy the Victron SmartShunt battery monitor which doesn't come with a display.

[tt2retire]

I think I just found the best route for getting my solar cables (4awg) to my roof. This should work just as well for the 21RBS as my 21BHS. I'm curious what you all might think.

There is a very clear path from the floor to the ceiling in the wall that the fridge and shower share. I put a camera in there and can see all the way through. On the underside of the trailer it gets too conjested before the shared wall on the way back, So I'm planning on popping up from underneath into the big open space around the furnace under the fridge, and cable tying the wires on the perimeter of the floor of the open space to get back to the wall cavity. Both holes in the roof and ceiling will be lined with 1in PVC pipe to protect the wires and help seal the openings. On the roof I'll make sure that the new opening is far enough away from the vent cap so that I can install a waterproof cable junction box (see https://youtu.be/aB8ic6x9DAM).

I'll also install a solar combiner box on the roof in the middle just behind the AC unit (see https://youtu.be/zUsSwLaXzHM).

Finally, I'll use the latest RVWithTito method to install the three SunPower 110W flex solar panels (https://youtu.be/uJIEXhnF8MU). I'll do a slight modification to this method by adding aluminum angle iron to better secure the front and back lattice end caps to the tracks.

I thought a lot about using ridged panels, but I'm most concerned about weight, as I might end up with four panels given how well a forth panel may fit.

Picture shows where I plan to place the panels and two new boxes.

[tt2retire]

2nd try at attaching the correct picture with boxes shown in red. Three solar panels are the cardboard pieces

[DavidM]

You should be aware of two things about flexible solar panels: they deteriorate over time more than rigid panels: I had three early flexible panels that only put out half of their rated wattage after five years. The other is that they are less efficient so it takes more panel area to make the same power as rigid panels. You might be able to fit four panels in place easier with rigid panels.

What kind of solar controller are you planning to use?  With three panels I don't think you are going to wire them in series but with four you could wire them in series/parallel and minimize voltage drop in the wiring. You will need a MPPT and not a PWM controller to do that.

David

[Merlin]

The wire routing seems fine. Your on the right track to protect the wire from sharp aluminum edges. And, of course, think through where either 12V or 120V may be in the ceiling before getting out the hole saw! And, finally, you can't use too many wire ties on camper wiring; it's a rough ride 

[GrampaKilt]

And, finally, you can't use too many wire ties on camper wiring

And, therefore, has been added a new phrase to the vaunted lexicon of ACF speak: TANSTATMCT
(There ain't no such thing as too many cable ties) GK

[tt2retire]

I agree there are limitations with regard to using flex solar panels. I did look into the AM Solar rocker foot mounts along with the Renogy 100W eclipse panels, but feel more comfortable with the weight, look and substantial attachment method on the flex panels for no drill mounting. Time will teach me more about how long they last.

For the roof panels I'm using a Victron SmartSolar MPPT 100V/30A CC. Agree with the 3 vs 4 panel wiring suggestions. With the terminal block in the combiner box I will have the ability to play around with the final configuration. I'm wondering if 4 panels and a VOC spec of 22.8V each (91.2V) if that could potentially be a sweet spot.

Also agree with the TANSTATMCT approach. I'm not sure how many I'll be able to install through the wall cavity but I'll give it a good shot.


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[Merlin]

Charge controllers are rated by the maximum amps they can send to the battery(s). In a 12V system those amps get real high real quick when using multiple solar panels. For example, if you have 330w of panels in parallel on a 12v system, you could have 27 amps going into the batteries, which is very close to the 30A capacity of the Victron CC. That's fine, but it won't take any more!

[tt2retire]

Finally done with installation. I went with the left two panels in series, the right two panels in series, and then the left and right panel sets in parallel. The two victron charge controllers (roof, portable) really work well together since they're networked via Bluetooth.

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