Can I Feed Three Meters Using Polaris Taps

PV Interconnection

The majority of US residential and commercial PV systems are grid-interactive (or grid-tied ), which means that they are designed to be able to export excess power to the utility grid. Export occurs when the power generated by the solar system is greater than the power used by the loads on site. A photovoltaic system will be given permission to interact with the power grid only after a formal approval has been issued by the utility. The process through which a utility verifies a solar system's compliance to its technical and administrative requirements is commonly referred to as interconnection process .

The interconnection process runs in parallel with the permitting process . During this process, the local Authority Having Jurisdiction (AHJ) verifies the system's compliance to the National Electrical Code, Fire code and other local standards. While the AHJ and the utility company will generally not interact during the process, they will require and recognize each other's approval documents.

During the interconnection process, utilities certify that a PV system meets the following general requirements:

a) The power exported to the grid is measurable and compliant with the grid's standards in terms of voltage, frequency, power quality. that the equipment used is certified

b) The AC side of the PV system (between the inverter and the utility meter) meets the utility's safety requirements (labeling, location of equipment, connection to electric panel)

c) The power and energy generated to meet the net metering program requirements

To gather the necessary information about the proposed system, utilities usually require that an interconnection application is submitted to their interconnection department. The application may be submitted by the account holder or, when properly designated, by the contractor that designs and installs the PV system. The interconnection application usually includes professional technical drawings, such as site plans and an electrical diagram.

In the parallel permitting process, the AHJ will complete the inspection and, when passed, will issue a signed final permit .

Once the utility has received the approved final permit, it will schedule an inspection of the installed system. During the site visit, performed by qualified utility personnel, the solar system will be tested, and, if necessary, revenue meters installed and/or replaced. When the system is approved, the utility will notify the account holder and the installer, which will then be able to turn on the system and export power to the utility grid.

Connection to the Main Panel

Grid-interactive systems have a physical connection to the existing electrical equipment, which is electrically continuous with the power grid. The technical requirements for interconnecting a customer-owned generator are listed in a technical document (usually called Electrical Service Requirements) that is published by the utility company. The physical connection to the electrical equipment can be done according to one of the following methods:

Circuit breaker connection :  The AC wires from the inverter are connected to the electrical panel through a circuit breaker. This is the most common type of connection with residential systems and is always allowed by utilities. It is also used with commercial applications, whenever the main panel is able to accommodate the PV backfeed current.

The overcurrent protection devices are the main circuit breaker and the PV backfeed circuit breaker in the electrical panel.

Image courtesy of Home power Magazine

Load-side tap connection :  Applied when there are no circuit breaker slots available. The wires are connected directly to the existing wires, between the electrical panel and (on the load side of) the main breaker. Some utilities do not allow this connection or do so only if it is approved by a professional electrician. The overcurrent protection device is the main breaker. Some utilities, however, may also require a fused AC disconnect between the inverter and the tap location.

Line-side tap connection :  This method requires that the wires from the inverter are connected to the service wires on the line side of the circuit breaker. This connection is very rarely allowed for residential systems but is increasingly common in commercial systems. Utilities usually require that the design for this connection and the installation are approved by a professional electrician. Once the utility engineers have approved the line side tap connection, it is necessary that a transformer power shutdown is scheduled, to allow the electrical contractor to perform the connection on wires that are otherwise connected to the utility grid.

The overcurrent protection device is the PV fused AC disconnect.

Image courtesy of Home power Magazine

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8 years 2 months ago

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Source: https://www.greentechrenewables.com/article/pv-interconnection-load-side-vs-line-side

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