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
There are certain factors you need to consider to ensure a safe and efficient setup which we will take about later in the article.
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 with each other.
Below you can find a diagram of such a system running one or more appliances.
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 0.5. Using the same example of a 12V, 100Ah battery:
0.5 x 100Ah = 50A
50A x 12V = 600W
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 C/2 = 500Ah
You need a 12V, 500Ah battery to support a total of 3000W inverter power.
You might ask, what is C/2? That is the C-rate of a lithium battery. In this case, we need to multiply by 2 because the C-rate is 0.5, and the calculation is reversed. Let’s do that to check the calculation:
0.5 x 500Ah = 250A
250A x 12V = 3000W
There you have it.
If you have a lead acid battery, multiply by 5 (C/5) instead of 2 (C/2).
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 together.
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.