Solar Suitcase & OEM system?

[HoosierB]

First, I apologize if this topic has been covered before and archived. I did a search, and most threads just "lightly touched" the subject.
I'm looking into the flexibility of additional solar power by using a "portable suitcase".
My questions are:
Can a 100W solar suitcase be combined with the existing OEM solar system? If so, how is that done? Would like to have an exterior plug-in rather than using temporary alligator clips.
Or, does the suitcase need to standalone from the OEM setup and include its own controller?

I have a SunForce controller/charger (same OEM location) and plan on upgrading the OEM 50W roof solar panel with one Renogy 100W mono/Eclipse using existing wiring. If combined, the 100W suitcase will make my goal of a total 200W system.

[chin_k]

As long as the SunForce controller can handle the 200W and the wiring is thick enough, then you should be able to add a "tap" somewhere between the SunForce and the existing panel, and plug in the extra suitcase.

However, I kind of remember (sorry, getting old and lazy here) that the existing wiring for the stock panel is probably undersized if you go above 50W. I would check the following:
1, what is the watt rating of your SunForce?
2, what is the wiring size between the SunForce and the existing panel?
3, what is the wiring size between the SunForce and the batteries?

After confirming that you are good to go, or you can do the upgrade, then you can decide where to add the tap for the suitcase. You can have it as external adapter when you upgrade the wiring for the 100 W Eclipse panel, for example, or you can have a separate spot elsewhere. If you prefer internet connector, then you have more choices. I have a bunch of Anderson connectors, so I will probably use them. They do offer waterproof housing for them. There are many other choices.

The following is an example:
https://www.amazon.com/Link-Solar-Weath ... 83&sr=8-18

[HoosierB]

1, what is the watt rating of your SunForce?
2, what is the wiring size between the SunForce and the existing panel?
3, what is the wiring size between the SunForce and the batteries?

Thanks for the detailed reply chin_k...
Answers to your questions:
1. Sunforce handles up to 30 amps of array current and up to 450 watts of solar power
2,3. All wiring is stock OEM at this point. I was following Clay's great blog (Chinook Power System Upgrade) where he found the existing wiring to be satisfactory for his 150W upgrade with the Sunforce "plug-in play". Maybe I forgo the new Renogy 100W roof panel and just mod for the 100W suitcase?

[chin_k]

I am sure Clay will chime in shortly, but how much more work is it for the additional 50W? One good thing about the roof panel update route is that you can forget about it once it is set. There are advantage to both portable suitcase and fixed roof setup, and another alternative that you did not mention is going with 100 W Eclipse upgrade on roof. The old 50 Watt original panel can be used as the "portable" or suitcase (more like a surfboard....) panel on the ground if you don't have space for it on the roof.

[HoosierB]

My thought was the existing wiring handling 150W opposed to 200W. I'm "electrically challenged" on these things
Whatever happened to Blue-Go??? Haven't heard from him in months.

[chin_k]

Yeah, Blue probably ran off to some nice place without Internet, and enjoying his time. I missing him too.

If you post a link to Clay's blog, maybe I can take a quick look and see if there is enough margin to put 200W on it. If the wiring from the controller to the batteries is good, it is possible to get the suitcases to tap into the controller right at the controller terminal, so that you don't have to worry about the load on the wiring between the controller and the panel on the roof. I think the wiring between the controller to the battery is not too difficult to replace, if you have to do that, since it is just across the cab, down the driver side column, and into the battery case under the chassis.

[HoosierB]

I like the idea of "tapping the suitcase" close to the controller with a short run to the exterior, plus a connector plug.
Link to Clay's Retirement Blog:
http://clayrushing.com/2017/01/21/chino ... -upgrades/

[chin_k]

Thank you for the link.

The wire seems to be only 12 AWG, so it can handle 20 amp, or at 12 V, it is 240 Watt. However, the voltage drop is an issue here. At 20A, with 12 AWG, you will be loosing 0.063 volt per feet. If the voltage drop is not important (it does, since efficiency mean cost, and you are paying dearly for the solar energy), then you can go ahead with the extra 50 or 60W (5 ampere is 60 watt). In comparison, at 15A, the voltage drop is 0.047 V/ft.

The difference of the 60 extra Watt is that it will give you 2 extra watt in penalty, so you are only getting 58 W more by not having to upgrade the wiring (it is about the same for a 50 watt panel). If you tap the suitcase at the controller, and assume it is half way to the battery (it is more, however), then the penalty will be around 1 Watt.

So you can go ahead with 200W system, but it is just not as efficient as one with a bigger wire than 12 AWG. I would go with 8 AWG at minimum, with 0.025V drop per feet at 20 A, or almost 1/3 of the voltage drop. If you can get 6 AWG in there, then the drop will only 0.016 V/ft. It all has to do with a good compromise between cost, physical limitation, installation effort, and efficiency.

Edit: Ideally, you do not want more than 1% or 2% of voltage drop, since it make a big difference to your controller and batteries.

[Scott]

Hi Hoosier. Precision calculations aside, it's worth noting that solar panels degrade over time. 20 years is well into the useful life of an already outdated system. If I were going to do a reliable, efficient solar system, I would start fresh. That's personal preference of course, and there are many viable arrangements, but I feel you'll save watts and time in the long run with new/modern stuff. Wire is relatively cheap, so it's worth using the good stuff, and give yourself plenty of headroom to allow for increased capacity in the future if needed. Let us know what you end up doing. I love hearing about others' strategies.

The first thing is to determine is what you intend to power.

[HoosierB]

Excellent points, Scott. Thanks! With the idea of doing a solar upgrade sitting on the back burner for awhile, I've decided it's time. And yes, there are quite a few "variable arrangements" out there. I'm leaning toward your idea of a total redo including the wiring upgrade and an MPPT controller. Replacing the rooftop panel with a Renogy 100W mono and supplement that with the flexibility of a Renogy 100W portable suitcase, with the option of adding another 100W rooftop in the future if needed. Research suggests that relocating the charge/controller closer to the battery bank is highly recommended. Oh boy...some fun.