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.
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
- 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.
- Hire a licensed electrician certified by the local jurisdiction to install the electrical equipment associated with the electrical service panel.
- 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.
- Record the location of the future PV system and all of its components on relevant architectural diagrams to be provided to the homeowner.
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.
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.
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:
- 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;
- Location does not have significant natural shading (e.g., trees, tall buildings on the south-facing roof, AND;
- Home as designed has adequate free roof area within +/-45° of true south as noted in the table below.
(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.
Retrofit:
2009, 2012, 2015, 2018, and 2021 IECC
Section R101.4.3 (Section R501.1.1 in 2015, 2018, and 2021 IECC). Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with this code. (See code for additional requirements and exceptions.)
Section 401.3 A permanent certificate shall be posted on or near the electrical distribution panel that lists types and efficiencies of water heating, heating, and cooling equipment, as well as insulation R values, and window U and SHGC factors.
Retrofit:
Section R101.4.3 (Section R501.1.1 in 2015 and 2018 IECC). Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with this code. (See code for additional requirements and exceptions.)
2009, 2012, 2015, 2018, and 2021 IRC
Section N1101.3 (Section N1107.1.1 in 2015 and 2018, N1109.1 in 2021 IRC). Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with this code. (See code for additional requirements and exceptions.)
Follow the requirements for solar water heating systems found in the 2009 IRC Section M2301 Thermal Solar Energy Systems (Solar Systems in IRC 2009).
Retrofit:
Section N1101.3 (Section N1107.1.1 in 2015 and 2018 IRC). Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with this code. (See code for additional requirements and exceptions.)
Appendix J regulates the repair, renovation, alteration, and reconstruction of existing buildings and is intended to encourage their continued safe use.
2009, 2012, 2015, and 2018 International Mechanical Code (IMC)
Follow the requirements for solar water heating systems found in the IMC, Chapter 14, Solar Systems.
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.
This Retrofit tab provides information that helps installers apply this “new home” guide to improvement projects for existing homes. This tab is organized with headings that mirror the new home tabs, such as “Scope,” “Description,” “Success,” etc. If there is no retrofit-specific information for a section, that heading is not included.
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.
The following authors and organizations contributed to the content in this Guide.
Building Science Corporation, lead for the Building Science Consortium (BSC), a DOE Building America Research Team
Pacific Northwest National Laboratory
Solar Electric Ready Home = Solar Electric Ready Home
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.
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?