Two Inverters on one Battery Bank ‣ Clever Solar Power

Yes, you can have two inverters connected to one battery bank. We can have two different kinds of inverters, these are:

• Synchronized inverters running the same loads
• Separate inverters running separate loads

You need to consider certain factors to ensure a safe and efficient setup, which we will discuss later in the article.

Key Takeaways

• When connecting multiple inverters to a single battery bank, you can either use synchronized inverters for the same load or separate inverters for different loads.
• It’s important to ensure the battery bank has enough capacity and the right C-rate to handle the total power demand of the inverters.
• Never connect the outputs of two or more inverters that are not synchronized.

Synchronized Inverters

If you plan to use two inverters simultaneously to power the same appliances, you must choose inverters that can synchronize their outputs.

Some off-grid inverters are specifically designed to work together in parallel and include built-in synchronization features. They are usually connected with an ethernet cable to synch their output. That way, they can put out the same voltage and frequency, and their sinus waves are synched.

Below is a diagram of such a system running one or more appliances.

With synchronized inverters, you can create 3-phase systems. This is not possible with separate inverters.

Separate Inverters

If you choose this setup, it can have two reasons:

• You want to add an inverter to your existing system for more power.
• You want a more efficient inverter to run your fridge 24/7

If the two off-grid inverters are meant to power different sets of appliances or loads, synchronization might not be necessary. In this case, you can use two separate inverters connected to the same battery bank, each serving a different load.

A diagram of such a system can be seen below:

Things to keep in mind when you wire two inverters to one battery

Connecting two inverters to the same battery is easy.

But there are some extra calculations and considerations we need to do.

C-rate

The C-rate is how fast a battery can discharge. For example, a 12V, 100Ah lead-acid battery has a c-rate of 0.2.

0.2 x 100Ah = 20A

This means you can discharge the battery at 20 amps to achieve a long battery lifespan. The total power will be:

20A x 12V = 240W

So you can only have a 240W inverter on a 12V, 100Ah lead-acid battery.

Now, lithium has a C-rate of 1. Using the same example of a 12V, 100Ah battery:

1 x 100Ah = 100A

100A x 12V = 1.200W

We can see that we can have a larger inverter if we use lithium.

The point I want to make here is that you cannot just add another inverter. You need to calculate the C-rate of your batteries and the inverters.

Let’s say you have a 2000W inverter and want to add another 1000W inverter.

2000W + 1000W = 3000W

3000W / 12V = 250A

250A x 1C = 250Ah

You need a 12V, 250Ah battery to support a 3000W inverter power.

If you have a lead acid battery, multiply by 5 (C/5 or 0.2C):

250A x 5 = 1250Ah

Wiring and Safety

Proper wiring and safety precautions are essential when connecting multiple inverters to a single battery bank. Use appropriately sized cables, fuses, and circuit breakers to ensure a safe and efficient setup.

• Read my guide on how to size wires here
• Read my guide on how to size fuses here

Conclusion

It is possible to connect two inverters to the same battery bank. Either you choose inverters that can communicate with each other or you have two separate inverters powering a different load.

Never connect the output of two separate inverters.

FAQ

How many batteries can be connected in parallel to an inverter?

You can have as many inverters in parallel as you want. Remember that the inverters need to communicate with each other OR have each their separate load. Never connect the output of two or more inverters that are not synchronized. You also need to keep in mind the C-rate of your batteries.

Read more: How many batteries for a 3000W inverter?

I’m an off-grid enthusiast. I created this website to give clear and straight-to-the-point advice about solar power. I’m also the author of the book ‘Off-grid solar power simplified‘. Read more about me on my about page, check out my Youtube channel, or send me a message.