Finding a Solar Roof Top Combiner Box For Your RV (4 Options)
The term combiner can be replaced by the term ‘junction’ and you should know what a combiner box is. It is a box that holds the different connections for solar wiring, etc. This box is where most components meet and join together. They may also be called a C-box when advertised.
There seem to be quite a few retail outlets that offer this type of box for sale. AM Solar does, as does Amazon. You may find the word junction box at that latter outlet though. Those models work just as well as they are water and dust-proof.
To learn more about this topic, just continue to read our article. It brings you the best information on these boxes and where to find them. Take a few minutes to see if this information solves a search problem for you
What is a Solar Rooftop Combiner Box?
This is for those RV owners that have not used solar power or do not know what a combiner box is. If you are not big on electronics the explanation may be a bit technical so we will try to simplify the explanation.
As you know, solar panels produce electricity. That electricity needs to go somewhere. If you have more than one panel, they are connected to what are called solar strings. Those strings are then connected to a fuse in a combiner box and those fuses are wired to one single conductor.
That conductor brings the electricity to the inverter which then turns the power into usable electricity. That is the duty of the most basic combiner or junction box. We will use the term junction interchangeably because that would be the proper and most common term to use.
You can buy additional equipment to make your combiner box more sophisticated and do more things. Those additional pieces of equipment include disconnect switches, monitoring equipment, remote rapid shutdown devices, and more.
What these junction boxes can do as well as reduce the amount of wire used to conduct that electricity from the solar panel to the inverter.
Types Of Combiner Boxes
There happens to be more than one type of these junction boxes. The one you get will depend on your solar power design and purpose. The following list is comprised of only the most common types. You may find more when you talk to a solar panel outlet:
- Fused Solar Combiner Boxes
- Pre-wired Solar Combiner Boxes
- Non-Fused Solar Combiner Boxes
- Dual Fused Solar Combiner Boxes
- Solar Combiner Boxes with Circuit Breakers
- Multi-String Solar Combiner Boxes
These junction boxes are made for outdoor use and come with one of the following ratings- NEMA 3R, 4, or 4X ratings, with NEMA 3R being the minimum requirement for outdoor use.
Plus, they are made from fiberglass, plastic, and painted steel. If you live or camp in a humid area, you would need one with a breather vent installed or add one yourself. You will find these combiner boxes located on the roof of your RV or travel trailer. Right where the solar power wires are laid out.
You can get low-profile models also if you have a height issue. The one issue you should be aware of is that if your RV or trailer only has one, two, or even three strings, you do not need a combiner box.
These junction boxes are made for larger projects that have 4 or more strings coming into them. The advantage of using them on your RV with under 4 strings is that you have an easier time with installation, disconnection, and maintenance. You do not need a large junction box to meet this benefit.
The other good aspect about using these boxes is that they need little maintenance. But you should inspect them from time to time to make sure nothing has been damaged.
RV Roof Combiner Box Options
Amazon has quite a few brands selling their combiner boxes on that marketplace. The biggest difference between these boxes is the price. Some are relatively inexpensive while others are not.
You can pay the higher price or go with a regular junction box that does the same task but for a lot less money. Do a little comparison between the two and see how little difference there is between these two options.
We will get to AM Solar’s options in the next section. Right now we should warn you about the Zamp Combiner box. It seems that there is a little trouble with the built-in breaker. According to Zamp, the breaker is rated for 12 volts nominal component.
However, the technicians at Bussman say that it is rated for 14 volts. Bussman is involved because they make this part for Zamp. If you wire more than one solar panel to this junction box, you could have an electrical overload problem.
The end of the story is that this warning only applies to those Zamp combiner boxes made prior to 2017. Since then, Zamp has stopped including the breaker inside their junction boxes.
Then Northern Arizona Wind & Sun outlets sell the Array boxes but those options are not exactly cheap either. It would be a good idea to do some research and talk to qualified electricians and solar experts to make sure you get the right setup before you buy.
They will have the best info on which models of boxes are the best and may steer you towards the cheaper junction boxes since most RVs are not using more than 4 strings at one time.
The internet will provide you with many leads and all you have to do is contact them with an e-mail and ask your questions.
AM Solar Combiner Box
This is one of the more well-known solar combiner/junction box retailers. Their popular brand happens to be the Zamp model and it measures 5 1/4" W x 4 5/8" D x 1 7/8" H. It is made for small to the medium solar charging system and it sells for only $65.
The company says only this about this product:
- Up to 6GA output cable
- Up to 4 inputs
- 2 ATP input plugs
- 2 knockouts for 1/2" weather-tight fittings
- For Zamp Legacy SAE connections, use Zamp Compatible SAE Plug & Strain relief for C-Box
The company also sells the Roof C-Box which carries their name on the outside cover. It retails for $100 and the company simply states it is best for sealing roof penetrations. The device measures H 1.9" x W 11.61" x D 5.87" making it a very small junction box.
AM Solar works with RVs of all classes and they produce or sell a variety of solar equipment you could possibly use. You can find out more about those products and combiner boxes by clicking on this link.
They have an e-mail address for you to send in your questions.
What To Look For in a Combiner/Junction Box
There are several key aspects you should be looking at when searching for a top combiner box. The following list is designed to get you started on the right path:
1. conform to UL1741- faulty combiner boxes tend to cause a lot of problems even though they are not the most complicated or expensive piece of solar equipment. Those problems include flames and smoke.
2. Should meet the technical requirements of your solar situation- this is important as if you do not meet those requirements you could have problems later on. It may be okay to exceed those requirements but ask the professionals first before doing that.
3. Includes the new trend- what has been happening lately is that combiner box makers have been installing what are called whips. This is a piece of solar wire with a solar connector on one end.
Instead of having to drill a hole in the junction box and install fittings, you simply connect your solar panels to the whip’s connector, and you are done.
4. Meets the National Electrical Code- there have been recent changes made to this code. Those changes have made rapid arc-fault and remote rapid shutdown devices almost a standard component.
The NEC regulations tend to spark upgrades in technology and components because the Code is revised continuously. If your system is large enough, you may want to check into the following components- higher voltage components, integral mounting hardware, and custom grounding options.
Some Final Words
Having the right connections is important when it comes to solar power and electricity. That makes buying the right combiner or junction box to house those connections. You will find these items on sale at most solar products outlets and you just have to know which components you will need.
They may be found at the big box stores as well as they are becoming popular to use in RVs and travel trailer
