Interconnection equipment

Interconnection Equipment

Design

Balance of System components are the components that make the PV system work. This training will help you become familiar with these components as they relate to designing a PV system.

1 | CONNECTION TYPES

BREAKERS & TAPS

2 | BACKFEED BREAKERS

BACKFEED BREAKER REQUIREMENTS

3 | TAP TYPE CONNECTORS

TAP CONNECTOR OVERVIEW

FUSIBLE AC DISCONNECTS

1 | CONNECTION TYPES

BREAKERS & TAPS

The first things to familiarize yourself with in terms of interconnection equipment are

Backfeed breakers (Left)
Piercing Taps and Polaris Lugs (right)

2 | BACKFEED BREAKERS

BACKFEED BREAKER REQUIREMENTS

All PV breakers must be 2 poles/240V.

What’s the difference between 120V and 240V breakers?

First, lets define voltage again:

The measure of “push” available to motivate the electrical charge in the circuit.

See the diagram to the right:

Each bus bar is rated for 120V
120V breakers only contact one of the bus bars, therefor the continuous current is only 120V.

240V breakers make contact with both of the bus bars, therefore the continuous current is 240V.

EACH OF THESE BREAKERS TAKES UP 2 SLOTS (CONTACTS BOTH BUSBARS) AND SO THEIR CIRCUITS ARE SUPPLIED WITH 240 VOLTS

What’s the difference between a normal branch breaker and a backfeed breaker? Physically there’s no difference. The difference is completely dependant on how the breaker is being used.

Branch circuit breakers:

Draw energy from the bus bar to power loads in the home

Backfeed breakers:

Supply energy from PV to the residential busbar through the breaker.

3 | TAP TYPE CONNECTORS

TAP CONNECTOR OVERVIEW

Used to splice PV backfeed circuits to existing residential service conductors and feeders.

What are service conductors and feeders?

Service conductors and feeders are the conductors (wires) feeding a main service panel or sub panel.

PIERCING TAPS

What is a piercing tap connector?

PV wires connect to one side of the connector which pierces the insulation
The other side of the connector has piercing conductor plates that pierce the insulation of the existing service conductors or feeders.

Piercing taps are the default style of tap connections used at ION. It is worth noting that you must have 6" of conductor lenght in order to consider a tap interconnection using piercing taps.

POLARIS CONNECTORS

What is a polaris connector?

The existing service conductor or feeder is cut into two sections landing in two separate lugs in the Polaris connector.
The PV wires are spliced to the center lug.

Polaris connectors are only used when the utility/AHJ requires a tap box type interconnection or when we are tapping cloth wires.

They may also be used when there is less than 6" of conductor to splice to for a typical tap:

this method will require the existing conductors to be removed from the main lugs and placed into the polaris connector.
Then the feeders can be extended by adding new conductors of the same size on one of the other terminals of the connector and landed back into the main lugs of the panel.

4 | OCPD

WHAT IS AN OCPD?

An Overcurrent Protective Device is a device used to protect conductors and bus bars from overcurrents such as:

Overload: when too much current passes through electric wires.
Short circuit: when a low-resistance path not suited to carry electricity receives a high-volume electrical current, usually caused by faulty connections in circuit wiring.

A LOAD SIDE BREAKER TYPE INTERCONNECTION IS BOTH THE INTERCONNECTION METHOD AND THE OCPD

A BREAKER TYPE DISCONNECT ENCLOSURE PROTECTING AN INTERIOR TYPE SUPPLY SIDE TAP

A FUSIBLE DISCONNECT PROTECTING AN EXTERIOR TYPE SUPPLY SIDE TAP

All PV circuits are required to have an OCPD ahead of the point of interconnection. Here at ION we utilize one of two types of OCPDs for PV circuitry:

Breakers
Fuses

BREAKERS

For backfeed breaker type interconnections, the breaker is both the point of interconnection and its own OCPD.
- For this reason, backfeed breakers are generally preferred over taps.
In some circumstances, a 2 pole breaker type enclosure might be used for an interior tap rather than a fusible AC disconnect. We’ll talk more about this later on.