Combiners

When using more than one Blue Ion battery cabinet from Blue Planet Energy you may want to use a third party battery combiner to share the power and energy supply between all inverters and solar charge controllers associated with the system and all of the Blue Ion cabinets. For Schneider and Outback you can use the integrated DC power distribution panels with integrated disconnects to parallel several inverters, solar charge controllers and battery cabinets if that is a convenient solution for your site. In other cases you may want to use a separate DC power distribution combiner for the battery banks, solar charge controllers and inverters such as the Midnite MNBCB 1000 or the Marathon BFPB XX-X-X terminal block.

OCPD & Sizing

The safety and serviceability of the system is very important for dealers and project owners alike. With that in mind we always suggest that you evaluate each systems unique aspects when sizing conductors and over current protection devices (OCPD). The Blue Ion enclosure is equipped with a 250A breaker that serves as an OCPD as well as a service disconnect. This OCPD along with the OCPD associated with each individual inverter is often more than enough to protect the conductors and provide adequate disconnection means to meet both the local Authority Having Jurisdiction (AHJ) codes and standards as well as the National Electric Code (NEC) requirements.  However, in some cases an inspector, designer or system owner may require you to provide additional disconnection or over current protection into the system. When this is the case, the MN MNBCB 1000 is a great option for combining battery cabinets,  inverters and/or charge controllers all in one location with the associated breakers. If you are simply trying to combine the battery cabinets, inverters and/or charge controllers but do not require the associated OCPD or disconnects then the Marathon BFPB XX-X-X may be a nice option for your system. Be sure to size your OCPD and cabling to account for the maximum continuous current in the system, typically the combined inverter current draw. 

Stand-Alone Inverter Input Circuit Current:

The inverter maximum DC current is based on the maximum output power of all combined battery based inverters and is defined as: 

( Combined AC output Watts / (Lowest Operating Voltage * Inverter Rated Efficiency)

Example:

The Outback Radian 8048 has a max continuous rating of 8000 Watts, lowest operating voltage is 44VDC, with a 93% efficiency

8000W / (44V * 0.93Eff.) = 195.5 Amps

With consideration for continuous duty we must size our OCPD to 125% of the maximum rated current from the above calculation, thus:

195.5 Amps x 125% = 244 Amps is the smallest OCPD we can provide for this system.

This is why we chose a 250A main breaker to accommodate the Outback Radian high power capacity.

However, as many of you are aware, internally the Outback Radian is actually made up of two individual 4000 Watt inverters which is why the GS Load Center has two 175 A breakers instead of a single 250A Breaker.  

As you add more inverters in parallel you simply add the maximum expected current to appropriately size your conductors and over current protection devices. 

There are many variations in design and layout so be sure that you understand that this is only one example. Please adjust your calculations according to the equipment you will be installing as well as the local codes and standards for your area. 

 

For more insight and design review considerations please contact support@blueplanetenergy.com

 

___________________________________________________

Reference Text below from the NFPA 70 NEC 2014 690.8

 (4) Stand-Alone Inverter Input Circuit Current.

The maximum current shall be the stand-alone continuous inverter input current rating when the inverter is producing rated power at the lowest input voltage.