70-Amp Dual-Pole Circuit Breaker for PV Systems

    Scope Images
    Image
    Electrical service panel
    Scope

    To construct a home that is prepared for the installation of a future solar photovoltaic (PV) system:

    • Include a dedicated 70-amp dual-pole circuit breaker.
    • Place the circuit breaker panel box near the future balance of system components for the PV. 
    • Consider space requirements and layout within the home and on the roof for solar photovoltaic system components early in the design process. 

    See the Compliance Tab for related codes and standards requirements, and criteria to meet national programs such as DOE’s Zero Energy Ready Home program, ENERGY STAR Certified Homes, and Indoor airPLUS.

     

    Description

    A renewable energy-ready home (RERH) is one that is built with the wiring and plumbing conduit and other components in place to facilitate the future installation of solar photovoltaic (PV) panels and/or solar water heating panels. Some energy-efficiency programs, like the U.S. Department of Energy’s DOE Zero Energy Ready Home Program, require homes to be renewable-energy ready.

    To prepare for a future PV system to be connected in a home, install a dedicated double-pole circuit breaker in the electrical service panel or in a separate subpanel. The breaker is intended for protection of the PV modules and wiring from reverse current flow. The breaker should be appropriately sized for the PV array that is being installed.

    How to Install a 70-Amp Dual-Pole Circuit Breaker

    1. To meet the requirements of the DOE Zero Energy Ready Home program, designate a dedicated space in the electrical service panel for a dual-pole circuit breaker.
    2. Hire a licensed electrician certified by the local jurisdiction to install the electrical equipment associated with the electrical service panel.
    3. Label each breaker in the service panel with water-resistant labels. The breakers dedicated for the future PV system should read, “Renewable Energy Ready Home – Solar PV Dedicated Breaker.”  See Figure 1.
    4. Record the location of the future PV system and all of its components on relevant architectural diagrams to be provided to the homeowner.
    Electrical service panel with dedicated breaker for future PV system.
    Figure 1. Electrical service panel with dedicated breaker for future PV system (Source: Courtesy of US EPA).

     

    Ensuring Success

    Ensure adequate space in the electrical service panel for a dedicated dual-pole breaker, early in the design process. If possible, place the circuit breaker panel box near the future balance of system components for the PV. Confirm with local code officials early in the design process what steps are needed to guarantee that installation of PV panels will meet with local codes, homeowner's association covenants, and historic district regulations.

    Protect the electrical and mechanical components of the PV system from bulk moisture, high temperatures, and direct sunlight. The utility room should be properly ventilated and maintain average indoor temperatures. Proper clearances and working spaces should also be maintained.

    Climate

    The DOE Zero Energy Ready Home PV-Ready Checklist (Revision 07)  is required only under the following condition related to climate (See the Compliance Tab for other exceptions):

    • Location, based on zip code, has at least 5 kWh/m2/day average daily solar radiation based on annual solar insolation using the PVWatts online tool. See map below. 
    Average daily solar radiation per month.
    Map of average daily solar radiation per month.

     

    Presentations

    Compliance

    The Compliance tab contains both program and code information. Code language is excerpted and summarized below. For exact code language, refer to the applicable code, which may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.

     

    DOE Zero Energy Ready Home (Revision 07)

    Exhibit 1 Mandatory Requirements.
    Exhibit 1, Item 1) Certified under the ENERGY STAR Qualified Homes Program or the ENERGY STAR Multifamily New Construction Program.
    Exhibit 1, Item 7) Provisions of the DOE Zero Energy Ready Home PV-Ready Checklist are Completed.

    DOE Zero Energy Ready Home PV-Ready Checklist (Revision 07)

    • Install a 1” metal conduit for the DC wire run from the designated array location to the designated inverter location (cap and label both ends). (RERHPV Guide 3.2)
    • Install a 1” metal conduit from designated inverter location to electrical service panel (cap and label both ends). (RERHPV Guide 3.3)
    • Install and label a 4’ x 4’ plywood panel area for mounting an inverter and balance of system components. (RERHPV Guide 3.1)
      Alternative: Blocking is permitted to be used as an alternative to the 4’ x 4’ panel. The area designated for the future panel to mount PV components shall be clearly noted in the system documentation.
    • Install a 70-amp dual pole circuit breaker in the electrical service panel for use by the PV system (label the service panel) (RERHPV Guide 3.4)
      Alternative: Provide a labeled slot for a double-pole breaker in the electrical service.

    DOE Zero Energy Ready Home National Program Requirements Mandatory Requirement 7 (Renewable Ready) shall be met by any home certified under the DOE Zero Energy Ready Home program, only where all of the following conditions are met:

    1. Location, based on zip code has at least 5 kWh/m2/day average daily solar radiation based on annual solar insolation using PVWatts online tool, AND;
    2. Location does not have significant natural shading (e.g., trees, tall buildings on the south-facing roof, AND;
    3. Home as designed has adequate free roof area within +/-45° of true south as noted in the table below. 
    DOE Zero Energy Ready Home PV-Ready Checklist - Minimum Roof Area (Revision 07).
    DOE Zero Energy Ready Home PV-Ready Checklist - Minimum Roof Area. (Source: DOE Zero Energy Ready Home PV-Ready Checklist (Revision 07).)

     

    Community Solar - If a home is served by a community solar system, it does not have to meet the PV-Ready Checklist provisions.

    Multifamily - For multifamily buildings, the PV-Ready provisions may be applied to the electric service for the building’s common space instead of being applied to each dwelling unit.

     

    2009, 2012, 2015, 2018, and 2021 International Mechanical Code (IMC)

    Follow the requirements for solar water heating systems found in the IMC, Chapter 14, Solar Thermal Systems ("Solar Systems" in 2009, 2012, and 2015 IMC).

     

    2014 National Electric Code (NEC)

    Follow the requirements for solar photovoltaic (PV) systems found in the 2014 National Electric Code (NEC), Article 690, PV Power Systems, and Article 110, Requirements for Electrical Installations.

    Existing Homes

    For a gut rehab where the objective is to renovate the home to meet the criteria of the DOE Zero Energy Ready Home program or a similar program that requires the home to be ready for the installation of solar panels, follow the new home guidance provided in the Description tab.

    For a renovation that includes installation of photovoltaic solar panels on an existing home, verify with the panel installer that the electrical panel has sufficient space and backfeed protection for the photovoltaic system desired.

     

    More Info.

    Access to some references may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.

    Case Studies
    References and Resources*
    Author(s)
    Brooks,
    Dunlop
    Organization(s)
    NABCEP
    Publication Date
    Description
    This Photovoltaic (PV) Installer Resource Guide is an informational resource covering basic requirements for PV installations intended for individuals pursuing the Photovoltaic Installer Certification credential offered by the North American Board of Certified Energy Practitioners (NABCEP).
    Author(s)
    Aldrich
    Organization(s)
    CARB,
    Steven Winter Associates,
    SWA
    Publication Date
    Description
    Brochure on specifications for PV systems.
    Author(s)
    Building Science Corporation
    Organization(s)
    Building Science Corporation,
    BSC
    Publication Date
    Description
    Report aiming to "de-mistify" technology and economic considerations of residential PV systems.
    Author(s)
    U.S. Environmental Protection Agency
    Organization(s)
    EPA
    Publication Date
    Description
    The RERH specifications and checklists take a builder and a project design team through the steps of assessing a home’s solar resource potential and defining the minimum structural and system components needed to support a solar energy system.
    *For non-dated media, such as websites, the date listed is the date accessed.
    Contributors to this Guide

    The following authors and organizations contributed to the content in this Guide.

    Building Science Measures
    Building Science-to-Sales Translator

    Solar Electric Ready Home = Solar Electric Ready Home

    Image(s)
    Technical Description

    As solar photovoltaic (PV) panels have significantly come down in price, many homeowners are installing them to produce clean power and reduce their electric bills. Many more homeowners are likely to want this option for the future. Solar electric-ready homes make this possible with minimal to no disruption or cost penalty using simple no-cost/low-cost details and best practices integrated during construction. This includes ensuring adequate unshaded roof space for the PV panels, installing conduit from the attic to the electric service panel, securing documentation that the roof is designed to support the extra weight of the PV array, and providing adequate space near the electrical panel for balance of system components.

    Solar Electric Ready Home
    Sales Message

    Solar electric ready homes include additional design features and details that enable solar electric systems to be added in the future with minimal or no cost penalty. What this means to you is that your home is ready to offset all or most of its annual energy consumption with a solar electric system. Wouldn’t you agree it feels great to have the power to eliminate most or all of your utility bill whenever you want?

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