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How could I connect 3 separate 15 Kw batterys to one inverter?

S

SolarLvr12

New Member
Joined
Sep 27, 2025
Messages
55
Location
Mexico
Hello, my plan in the beginning of my setup was to have 3 batterys and one strong larger inverter but I ended up getting 3 of these 15kw batterys with 3 6kw growwatt inverters.These 3 growwatt inverters are junky and have caused me so many problems, I have to tun 1 of them off at night or it drains one of my batterys! So anyways I want to setup a new system where I have the 3 of the 15 kw batterys connected to 1 central inverter but this is 45 kw of battery so what kind of inverter would you recommend as I have no idea. One that can :

1.accept my 485 watt solar panels
2. not cost a fortune
3. receive 3 thick pairs of cables from these 3 batterys

Any ideas..?
 
Is Mexico adhering to US standard (split phase)? What's your max load?

Look for "self consumption" specs to reduce a battery drain.
I would expect about 70-100W self consumption for a big inverter.

Make sure it's a 110V/120V AC US version. Frequency is usually 50/60Hz adjustable or auto-detect. E-mail manufacturer for the self consumption.

Deye Single Phase 16KW Inverters - Efficient Solar Solutions

Find reliable single phase 16kw inverter solutions for hybrid solar systems. Deye inverters offer high efficiency and advanced features for home and commercial use.
www.alibaba.com

If you interconnect batteries and turn all inverters off, they will still charge batteries from solar.
Adding a single low self consumption 48V to AC (110V or split phase) may do the the trick.
Paralleling smaller inverters does not solve the high idle power drain, with axception of Victron, maybe.

Batteries can be connected together without any trouble, SOC should be close.
If batteries are not from the same manufacturer, it may be difficult to find a common protocol for Inverter-battery communication, but it can be operated without communication as well.
 
Last edited:
Im not sure what you mean, the solar pannles or inverters do not know what country they are in.This is all offgrid
 
SolarLvr12 said:
Im not sure what you mean, the solar pannles or inverters do not know what country they are in.This is all offgrid
Click to expand...
Different countries have different wiring standards. Mexico and Canada is similar to the US. Whether you are offgrid or not, some appliances in Europe wouldn't work in the US because of the frequency and voltage.
 
For anyone to help you we need to know the voltage 12v, 24v, 48v? 120v or 120/240v inverter. These details are important.

On a normal day, you would connect the batteries in parrallel and connect them to your inverter. This is if your batteries are 48v and your inverter is 48v.
 
Yes the entire system is 48 volt and the output is to a usa house standard of 110. I have 3 6kw inverters but want one good one of another brand that is not growwatt probabaly 12 to 15 kw...and will be able to handle the 45 kw of total batteries.Thanks
 
Just use bus bars.

6 inverters, 6 batteries, 2 bus bars.

IMG-9868.jpg
 
SolarLvr12 said:
Hello, my plan in the beginning of my setup was to have 3 batterys and one strong larger inverter but I ended up getting 3 of these 15kw batterys with 3 6kw growwatt inverters.These 3 growwatt inverters are junky and have caused me so many problems, I have to tun 1 of them off at night or it drains one of my batterys! So anyways I want to setup a new system where I have the 3 of the 15 kw batterys connected to 1 central inverter but this is 45 kw of battery so what kind of inverter would you recommend as I have no idea. One that can :

1.accept my 485 watt solar panels
2. not cost a fortune
3. receive 3 thick pairs of cables from these 3 batterys

Any ideas..?
Click to expand...
Which batteries? But yes, just connect your batteries to a bus bar and connect your new larger inverter to the same busbar. I like EG4 inverters but they may not meet your requirements.
 
You might want to double check the settings on the one troublesome inverter. Are you sure all settings are correct? Have you exchanged the battery with one of the others to verify it's not the battery? How much PV do you have charging these batteries? Are you sure that one battery is getting properly charged?
 
fatjay said:
6 inverters, 6 batteries, 2 bus bars.
Click to expand...
Love those compression plates, T-class fuses, but switches do not have a magnetic arc snuffing = do not turn off under load, especially the last connected one.
A work-around the "plate and springs" concept is a fixed setting with EVA foam inserts. The additional advantage is keepeng the pressure even over the whole battery side, thus not creating high pressure spots as the battery "breaths".
Combining EVA and pressure plates is even better, for 8 cells 9 EVA is needed.
That would compensate for EVA aging if there is any.
 
Last edited:
wpns said:
Which batteries? But yes, just connect your batteries to a bus bar and connect your new larger inverter to the same busbar. I like EG4 inverters but they may not meet your requirements.
Click to expand...
The batteries are from Big Battery, they are 15 kw big heavy things I can barely move...I will have to look into bus bar have never heard of this
 
wpns said:
Which batteries? But yes, just connect your batteries to a bus bar and connect your new larger inverter to the same busbar. I like EG4 inverters but they may not meet your requirements.
Click to expand...
could you explain a little bit how a bus bar works, it makes it one logical battery or..?
 
Connect up to 4 batteries rated 15 kw to the busbars in my post above. They are rated 600 amps which is exactly what four 15 kw batteries can provide. Cable from the busbar to the inverter(s). Use appropriate fuses and disconnects. You will be dealing with very dangerous levels of current. Also, all DC cables and connections should be enclosed either in conduit for cables or in a cable tray. Install the busbars in the cable tray and then cable via conduit to the batteries and to the inverter. Size the cables carefully, you will probably need at least 3/0 cable and maybe 4/0 depending on length and on the size of the inverter you install. I recommend using flex cable (aka welding cable) as it has more current carrying capacity and is a lot easier to work with on short runs.
 
He wants to take only 300A. (15kW)
The bigger is always better.
Google from EU gives me mostly 230V inverters, there are not too many 15kW single phase inverters in 110/120V AC.
The cheap ones may have a high self consumption, that is mostly missing in manufacturers' specs, it's a dirty secret.

(I've got 25W self consumption on 4kW inverter, that's about 0.5kWh winter night time drain, the battery is 7kWh, an acceptable pain.)
 
Last edited:
fatjay said:
1000a.
Click to expand...
Not for the bar you linked. That would only go up to 600 amps DC. But that business cuts any size any length. Just ask them for a bar 2 inches wide by 1/2 inch thick by 12 inches long and it would handle 1000 amps. The link below is oriented more toward AC conductance, but you can use the 30 degree centigrade rise numbers for DC capacity or calculate the capacity with this formula:

Current (Amps)=1200×Width (inches)×Thickness (inches)
=1200 X .5 X 1 gives 600 amps capacity

Copper Alloy C11000 Bus Bar Ampacity Chart - Storm Power Components

Ampacity table for bus bars having an emissivity of 0.4. Observed on samples exposed for 60 days in an industrial environment.
stormpowercomponents.com stormpowercomponents.com

With high amperage, double hole lugs should be used. That puts you with a bar at least 3 inches wide so the double hole lug will fit. It would apply to 2/0 and above cable sizes.
 
SnickeringBear said:
Not for the bar you linked. That would only go up to 600 amps DC. But that business cuts any size any length. Just ask them for a bar 2 inches wide by 1/2 inch thick by 12 inches long and it would handle 1000 amps. The link below is oriented more toward AC conductance, but you can use the 30 degree centigrade rise numbers for DC capacity or calculate the capacity with this formula:

Current (Amps)=1200×Width (inches)×Thickness (inches)
=1200 X .5 X 1 gives 600 amps capacity

Copper Alloy C11000 Bus Bar Ampacity Chart - Storm Power Components

Ampacity table for bus bars having an emissivity of 0.4. Observed on samples exposed for 60 days in an industrial environment.
stormpowercomponents.com stormpowercomponents.com

With high amperage, double hole lugs should be used. That puts you with a bar at least 3 inches wide so the double hole lug will fit. It would apply to 2/0 and above cable sizes.
Click to expand...
600a at 30c temp, but at 65c temp we're at 1000a.

The tube's size determines its Current Carrying Capacity (Ampacity). Once you have the Ampacity (Current, I) and the system's Voltage (V), you can calculate the wattage (Power, P) using the formulas:
  • For DC Circuits: P (Watts)=V (Volts)×I (Amps)
  • For AC Circuits (Single Phase): P (Watts)=V (Volts)×I (Amps)×Power Factor (PF)

Estimated Ampacity for 1/2′′×1′′ Copper​

A solid copper bar of this dimension is typically used as a busbar in electrical distribution. Ampacity tables provide different ratings based on the allowable temperature rise (e.g., 30∘C, 50∘C, or 65∘C rise above ambient temperature).
Using standard tables for C11000 copper busbars, the approximate ampacities for a single 1/2′′×1′′ bar are:
Rating ConditionAC Ampacity (Amps)DC Ampacity (Amps)
30∘C Temp. Rise≈620 Amps≈632 Amps
50∘C Temp. Rise≈820 Amps≈851 Amps
65∘C Temp. Rise≈940 Amps≈1,073 Amps

Calculating Wattage (Examples)​

To get the wattage, you must choose a current rating (based on your system's required safety/temperature rise) and apply the voltage.

Example 1: Low Voltage DC System (e.g., Battery Bank)​

  • Busbar Ampacity (I): 1,073 Amps (Using the maximum 65∘C DC rating)
  • Voltage (V): 48 Volts DC
  • Calculation: P=V×I
  • Capable Wattage: 48 V×1,073 A=51,504 Watts (or 51.5 kW)
 
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