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.
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?
Related Posts
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.
Hello. I have a 2 10Kva inverter and a 15KwH lithium batteries. I will like to connect them together. Please how do I do?
if you have a 48V battery, which I hope you do, then you will pull 400A+ from your batteries. If the battery is lithium and 15kW at 48V, I assume 3 100Ah, 48V server rack in parallel, then you can pull max 150A. So your setup is not properly balanced.
hi Nick. thanks for putting this up.
you specified to
“Never connect the output of two separate inverters together.”
is that just a recommendation and yet it can still work somehow? or is it a definite no no and dangerous or potential to wreck the equipment?
thanks in advance
You cannot connect two off-grid inverters because they will be damaged. You can only do this with on-grid inverters because they have phase synchronization.
Hi nick my friend has a estaurant set up,i installed 2 inverters ,running different lines each with 2x 200ah batteries,the batteries are linked in series which means i only have 200ah with 2 x 200ah the power doesnt last long enough when its loadshedding, can i connect the 2 inverters and sonehow connect the batteries to get 400ah out of the system,thx
Two batteries in series or parallel have the same energy density. Series: voltage increases, parallel: capacity (ah) increases.
12V, 200Ah x 2 batteries in series = 24V * 200Ah = 4.800Wh
12V, 200Ah x 2 batteries in parallel = 12V * 400Ah = 4.800Wh
The inverters will connect to the battery bank (two batteries in series or parallel). Look at my diagrams in the article.
I assume you have a 24V inverter, so no you cannot have 400Ah, but that’s not important, it’s the Wh that counts.
Hey nick, nice read! I recently ran 2 sun gold 6500w inverters in parallel and kept my old 5k up and running also, all pulling and charging the same set of batteries but They were feeding separate power boxes and worked great for about a week! Now the two parallel ones popped a fault 57 code and can’t find nothing on how to correct, tech support seems quite slow with them! Could the battery runs from both have possibly caused you know? Just seeking any answers now! Thanks in advance.
This is what I found in the user manual: ‘Buzzer beeps continuously and red LED is on. Fault code 08/09/53/57 Internal components failed. ‘ link to manual
Can you run the inverters in series from the battery? Ie is it possible to have a 96v battery source and use 2 48v inverters to split that 96v dc to the inverters.
In my case it’s how to possibly utilise a 80v 3kwh electric motorbike battery to 24v inverters as trying to find a 80v one is not easy etc.
Thanks.
No, that is not possible. The voltage will be the same (96V) over the two inverters. You could split the battery if that is possible. But there are some other concerns involved with that.
What about the charge settings on each inverter?
Using two independent inverter/chargers, would they both be configured to charge the common bank of batteries?
In my case, I’m considering two inverters, an MPP LV3048MK (which I already own) + a SolArk or EG4 15/18K model.
I know that the BMS on most LiFE batteries can only communicate with one inverter…. so if I needed to only use one of them to charge the batteries, that’d be fine. But I guess if both were connected to different banks of solar panels too, it’d be nice to have both able to charge (using the same bulk/float voltages I assume!?)
The BMS doesn’t have to communicate with the inverter. Checkout my article about having multiple charge controllers (or chargers) for a battery bank. You can use both charger/inverters at the same time. Just watch out for the C-rate.
I have 2 x alpha ess 6S which do not parallel but can run as grid connect or offgrid.
I am off grid,… is there a way of having one inverter as the off grid unit and the other inverter to think the first is a “grid” and so combine outputs and put into 1 circuit to power a heavier load than 1 can handle? Does the problem occur of perhaps setting the “grid connected inverter” to priority usage before taking power from the “grid forming” inverter, and so the battery of one would be cycled mostly with limited opportunity to charge as the other grid forming inverter would be fully charged unless the second went flat or could not provide the total load?
Is there some other workaround apart from purchasing dedicated offgrid paralleled inverters?
I’m not familiar with this type of battery and inverter in one. Your question is better sent to their customer support.