A parallel kit is one of the most useful accessories you can have for your WEN inverter generator. Over the last few years, inverter generators have become ever-more-popular choices for both home and recreational use, thanks to being remarkably efficient, quiet, and portable. But what if you need more power than a single unit can provide? That's where parallel kits come in. This article will delve into the theory of operation, best practices, and frequently asked questions about parallel kits to help you understand how they can maximize your WEN inverter generator's potential.

Introduction

If you're already familiar with the benefits of inverter generators, you know they provide clean and stable power, are fuel-efficient, and run more quietly than traditional generators. (If you’re not familiar, then before diving into the specifics, we recommend checking out our previous articles on the advantages of inverter generators, how to choose the right generator for your needs, and for the technically-inclined, a deep dive into how inverter generators work, as well as a discussion about total harmonic distortion in generators.)

For those looking to increase their power output without investing in a larger, bulkier unit, parallel kits offer a practical, cost-effective solution. These kits allow you to connect two inverter generators, basically doubling your power capacity.

Theory of Operation

Parallel kits work by synchronizing the output of two compatible inverter generators. The kit typically consists of a set of cables and a control module that ensures both generators are perfectly in sync, sharing the load appropriately. This synchronization is crucial because it maintains the stable, clean power output that inverter generators are known for, preventing damage to sensitive electronics and appliances. WEN parallel kits allow both inverters to communicate directly (without the need for a separate control module) to handle this synchronization, ensuring that both generators’ outputs are perfectly aligned (in electrical parlance, in phase).

In this picture, the generators' outputs are in phase, so everything will operate smoothly.

If the outputs weren’t aligned, the generators’ outputs would be reduced (below, first), or could even interfere with each other (below, second).

In the picture above, the generator's outputs are moderately misaligned. In the picture below, they're completely misaligned - in electrical parlance, out of phase.

As discussed in the deep-dive article we mentioned before, the key to parallel operation is the inverter itself. Unlike conventional generators, which produce power directly from the alternator, inverter generators first convert AC power to DC, and then use a computer to invert it back to AC. This double conversion allows for accurate and precise control of the output voltage and frequency. When two inverter generators are connected in parallel, the inverters ensure that both units operate in harmony - matching their phase, frequency, and voltage. This basically creates a “pool” of power that can be tapped into. You can tap into this pool from the parallel kit (if it has onboard outlets), or from the outlets onboard either generator.

How to Use a Parallel Kit

Using a parallel kit is straightforward, but safety and proper setup are paramount. Consult your generators’ and parallel kit’s owner’s manuals for detailed, specific instructions; the steps below are a general guide.

1. Determine your power needs. The best parallel kit for you may be different from the best option for someone else. WEN offers several parallel kits of varying capacities, from 3000W to 6000W.
2. Check compatibility. Ensure both generators are compatible with parallel operation and the parallel kit you intend to use. All 120V WEN parallel-capable inverter generators are compatible with all 120V WEN parallel kits, but the best parallel kit for your setup depends on your total power needs.
1. NOTE: make sure you get a parallel kit that matches your generator’s parallel outlets’ voltage. If your generator has two round receptacles (red and black), get a 120V parallel kit. If your generator has three square receptacles (red, black, and white), get a 240V parallel kit. You cannot mix and match 120V and 240V parallel kits and generators.
3. Connect the generators. Position the generators close enough for the parallel cables to reach, but far enough apart to allow for adequate ventilation and heat dissipation. NEVER run a generator indoors! ALWAYS run a generator outdoors, at least 20 feet away from doors and windows, to help prevent carbon monoxide poisoning.
4. Attach the cables. Connect the parallel kit cables to each generator's parallel ports.
5. Power on. Start each generator individually. Once both are running, connect the parallel kit to one generator at a time. The inverters will automatically synchronize.
6. Connect loads. Plug your appliances into the appropriate outlets on either generator, or the parallel kit, depending on your setup.

Safety and Best Practices

When using any generator and/or parallel kit, following best practices is essential to ensure your (and others’) safety and the longevity of your equipment.

• Use generators in well-ventilated areas. NEVER run a generator indoors! ALWAYS run a generator outdoors, at least 20 feet away from doors and windows, to help prevent carbon monoxide poisoning.
• Ground your generators. A grounding rod driven several feet into the earth is best. Ensure the parallel kit’s grounding wires are connected to the grounding lugs on the generators’ control panels.
• Avoid overloading. While parallel kits do increase your power capacity, ensure the combined output does not exceed the total wattage rating of the connected generators.
• Perform regular maintenance. Keep both generators in good working order so they’re ready to roll when needed. Check out our handy guide to generator maintenance, and consult your owner’s manual for detailed, step-by-step instructions and recommended service intervals.
• Store everything safely. Store everything indoors in a safe, dry place when not in use.

Which WEN Parallel Kit is Best for Me?

It depends on your total power requirements. Currently, WEN offers three parallel kit models. 

1. GNA25i - cord only, 5.5 ft long, maximum 3000W. Recommended for small inverter generators, or for those who need maximum portability and minimum storage impact. 120V only.
2. GNA36i - cord and panel, 5.5 ft cords, maximum 3600W. Features onboard cable storage. Recommended for small or medium inverter generators where a little extra power is needed. 120V only.
3. GNA50i - cord and panel, 7 ft cords, maximum 6000W. Recommended for medium or large inverter generators where maximum power is needed. 120V only.

FAQs

Can I get 240V from a parallel kit?

Some parallel kits and generators are designed to output 240V when used together. Most WEN generators are designed to operate at 120V only when using a parallel kit. Check your generators’ owners’ manuals and parallel kit manual for additional details and specifications.

Are there any power losses when using a parallel kit?

Generally, there are minimal power losses (usually less than 1%) when using a parallel kit, as long as the system is properly set up and the generators are compatible.

Can I use the outlets on the generators when using a parallel kit?

Generally, yes. Make sure you’re using outlets of the same voltage as the parallel kit (for example, you cannot use a 240V outlet when using a 120V parallel kit). Consult your generators’ owners’ manuals for specific instructions.

Can I run two generators of different sizes together? How does load balancing work?

Yes, you can connect any two WEN inverter generators, even if they aren't the same wattage. Think of the parallel kit as creating a “pool” of power to draw from. Whatever a generator's percentage contribution to the pool of power, that will be the amount it provides to the load - the inverters try to automatically balance the load.

For example, say you have two 2000W generators. Each will provide 50% of the required load (if the load is 1000W, each will provide 500W).

If you have a 2000W and a 3000W generator (total power 5000W), the 2000W generator will provide 40% of the load, and the 3000W generator will provide 60% (if the load is 1000W, the 2000W generator will provide 400W, and the 3000W generator will provide 600W).

What if the generators are rated for more (or less) power than the parallel kit can provide?

Say you have a parallel kit rated for 4000W. If you have 2 generators rated 1500W each, they'll only provide 3000W total to the pool of power that the parallel kit creates. So you can't get 4000W from this setup.

If you have two generators rated 3000W each (6000W total), if the parallel kit's electrical components (outlets, breakers, etc.) are only rated for 4000W, you'll only have 4000W available through the kit. To get the rest of the power that's available, you can use the outlets on the generators. Just don't overload the generators.

Can I run a WEN inverter generator in parallel with another brand of generator?

We do not recommend this. Our inverters are designed to communicate only with other WEN generators’ inverters. Mixing and matching may damage one or both of the generators.

Can I use other brands of parallel kits?

We do not recommend this, since we have not tested other brands’ parallel kits and cannot guarantee their performance or compatibility. Mixing and matching may damage one or both of the generators.

How do I use a parallel kit with a transfer switch?

Generally, follow the same instructions and recommendations as operating a single generator with a transfer switch. However, make sure that both of your generators are properly set up regarding neutral-ground bonding. The National Electrical Code (NFPA 70) stipulates that there must be only one point of neutral-ground bonding in a system, in order to avoid ground loops. If you have questions about this, consult your generator’s owners’ manual (including its wiring diagram), or contact a professional local electrician to ensure that you are operating in compliance with all local and national electrical codes.

Conclusion

Thanks for reading! If you have any questions about your generator, parallel kit, or just need help choosing which parallel kit is right for you, please give us a call at at 1-847-429-9263 (M – F, 8 – 5 CST), or drop us a message here to talk to our friendly and knowledgeable technical support team.