Choosing a Right Combiner Boxes for Solar Panels: Five Factors to Consider

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Why add to the cost of your already pricey solar power system by adding yet another component?

You might wish to avoid skipping the solar combiner box. The combiner box is relatively inexpensive in comparison to all of the other pricey equipment, but it provides your system with numerous additional benefits. You don’t want to choose the wrong combiner box after picking all of the panels, wiring, inverters, and any analytical software, batteries, or storage. When it comes to choosing a combiner box, the project type, size, and scope are crucial, and what works best for a home installation may not work for a commercial installation, and vice versa.

It’s not difficult to choose the correct solar combiner box manufacturer for the work, but you must first comprehend the site, the other components, and their relationship to the combiner. When speculating about your next job, keep these questions in mind. Let’s have a look at what to consider while selecting a combiner box for your solar system!

What Is a Solar Combiner Box

Ground fault Solar combiner box
Source: Pinterest

solar combiner boxes combine incoming power into a single main feed that is then distributed to a solar inverter. Through wire reductions, labor and material expenses are reduced. Overcurrent and overvoltage protection are built into solar combiner boxes to improve inverter protection and dependability.

The combiner box’s purpose is to combine the solar panels’ strings into a single box. Each string is connected to a fuse terminal, and the fuse terminal output is bundled into a single cable that goes to the inverter box. This is the combiner box’s most basic function, although it can be enhanced with additional functions such as a rapid shutdown button and monitoring equipment.

Between the inverter and the solar panels lies the combiner box. The box’s positioning must be a top focus, as poor placement might result in a loss of power efficiency. Combiner boxes are not required for homes with up to three strings, although they bring numerous benefits to any size system, regardless of size. Because a combiner in a less-than-ideal location may result in increased DC BOS expenses due to voltage and power losses, placement is critical. It’s only a few cents per watt, but it’s critical to get right.

How Simple Is It to Set Up?

solar combination installation
Source: Pinterest

The ideal combiner is often determined by its ease of deployment and installation, as well as the headaches it eliminates from the project. A box with pre-wired fuse holders and pigtails going out can be a plug-and-play solution that doesn’t require the installation of a licensed electrician.

Eabel, for example, debuted its Integrated Combiner Solution (ICS) in May, which is a one-stop-shop that includes prewiring, strain-relief cable glands, touch-safe distribution blocks, and bidirectional fuse holders. Installers will include them in every project if we make it as time-saving, cost-effective, and simple as feasible with a turnkey solution.

A combiner box isn’t necessary for projects with only two or three strings, such as a normal dwelling. Rather, you’ll connect the string to an inverter directly. Combiner boxes are only necessary for larger projects, ranging from four to 4,000 strings. Combiner boxes, on the other hand, can be beneficial in projects of all sizes.

Combiner boxes can bring a limited number of strings to a single area for convenient installation, disconnect, and maintenance in residential applications. Differently sized combiner boxes are frequently utilized in commercial applications to gather power from unusual building layouts. Combiner boxes allow site planners to optimize power supply boxes while lowering material costs for utility-scale projects.

What Functions Do You Need?

Simple photovoltaic power system for remote home system
Source: Pinterest

PV modules, inverters, Pv distribution boxes ( from reliable power distribution box manufacturers), meters, and power grids are typically included in a PV power generating system, and distribution boxes, while not accounting for a large percentage of the total system cost, play a significant part in the PV power production system.

It can just come down to price and availability when it comes to choosing a combiner box. There are off-the-shelf alternatives that pack in a variety of potential configurations for a residential installation, saving time and money over a custom solution.

However, because there are so many different panel layouts, the combiner may need to do more than just combine circuits and fuses, depending on the other components in the system. Not every manufacturer has the ideal off-the-shelf combiner box for every circumstance. Do you require flexibility or do you simply require simplicity? Let’s say you have two completely different solar systems that both go into the same box and then go to separate controllers. Some boxes can handle it without issue, while others may require custom construction.

Previously, all inverters were just grounded, and installers would parallel strings into a combiner before connecting them to the inverter. Transformerless inverters are now available that are ungrounded, requiring installers to fuse the negatives. The setup is more complicated and necessitates the use of a combiner box to bring everything together.

Today, you must first define the inverter before deciding on a combiner. “What inverter is being used?” “With so many inverter options available, ranging from typical string inverters to transformerless and transformerless with dual-channel MPPT, we had to narrow down our code-compliant disconnecting combiners to a few that would cover all of the bases.

Have You Considered Surveillance?

combiner box
Source: Pinterest

Wireless monitoring technology can be bundled inside the combiner box by some manufacturers, allowing for panel-level and string-level monitoring of current, voltage, and temperature. Monitoring gives real-time feedback when commissioning the field, in addition to the inherent benefits during the life of the installation. In this manner, any errors or faults will be noticed early on, rather than later. 

Combiner boxes require very little maintenance. The level of maintenance should be determined by the environment and frequency of use. It’s a good idea to inspect them for leaks or loose connections regularly, but a properly installed combiner box should last the life of the solar project. When choosing a combiner box, the quality is the most important factor to consider, especially since it is the first piece of equipment connected to the solar modules’ output. Combiner boxes are inexpensive when compared to other solar project components, but a faulty combiner box can cause a dramatic failure with flames and smoke.

The use of a whip, which is a length of wire with a solar connector on the end, is a new trend. We attach whips at the factory that allow the installer to easily connect the output wires to the box using a mating solar connection, rather than a contractor drilling holes in the combiner box and installing fittings in the field. Plugging in a toaster is all it takes.

Is It Capable of Safeguarding the System?

Solar combiner box
Source: Pinterest

First and foremost, make certain that everything you choose complies with the code standards in your jurisdiction. For a roof mount, the 2011 rule required everyone to install a disconnecting combiner within 6 feet of the array. The 690.12 codes need a quick shutdown of the system.

An arc fault is a high-power electrical discharge between conductors that generates a lot of heat. Insulation between wires gets broken down as a result of this.

The arc fault remedy must be connected to the inverter. Detecting an arc problem at the inverter for central inverters is challenging, according to Eric Every, senior applications engineer at Solectria, a Yaskawa firm.

“If the inverter has 100 to 200 strings, a fault on one string does not generate enough signals to indicate an arc when compared to the natural electrical sounds in the system,” says the author.

Detecting an arc above 50 kW gets significantly more challenging. Arc fault detection at the combiner level, rather than putting arc fault circuit at the inverter, gives more precise detection.

Because DC arcs produce a lot of electrical noise, arc fault detection works. The arc fault sensors are looking for noise signatures that signal a system arc fault. The frequency range for noise suggestive of arcs is similar to the natural switching noises from inverters, which is one of the issues in implementing arc fault detection.

The inverter may supply AFCI in conventional grid-tied systems, but the inverter is isolated from the PV array in battery-based systems. Positioning the AFCI in the combiner box, as close to the main source of arcing events as possible, not only improves visibility but also lowers the risk of “nuisance tripping.”

Because all arc fault events must be manually reset under the 2014 NEC, nuisance tripping is one of the main challenges with AFCI solutions. When an AFCI event occurs, whether it is a true arcing event or merely a nuisance trip, this can be a huge problem. Installers can lose time and money due to AFCI nuisance tripping.

Is a Combiner Necessary?

Combiner box
Source: Pinterest

Some locations may be able to connect everything without using a combiner, depending on the other materials used. The Big Lead Assembly (BLA) harness, which is essentially just a thicker gauge of wire capable of handling the arcing current voltage of the strings without the use of a combiner, made its premiere at Intersolar NA.

A combiner box isn’t necessary for projects with only two or three strings, such as a normal dwelling. Rather, you’ll connect the string to an inverter directly. Combiner boxes are only necessary for larger projects, ranging from four to 4,000 strings. Combiner boxes, on the other hand, can be beneficial in projects of all sizes. Combiner boxes can bring a limited number of strings to a single area for convenient installation, disconnect, and maintenance in residential applications. Differently sized combiner boxes are frequently utilized in commercial applications to gather power from unusual building layouts. Combiner boxes allow site planners to optimize power while lowering material costs for utility-scale projects.

Conclusion

A solar combiner box, which costs less than a couple hundred dollars, adds a lot of value to your solar power system. Phew! Fewer cords, improved efficiency, emergency disconnect, and higher security! Who wouldn’t want to put one of these in their home? They not only provide all of these advantages, but they are also simple to set up. I hope this article was useful to you, if you have any questions contact us, at Eabel, we will be glad to be of help.

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