Architectural Drawings for Solar Photovoltaic Systems

Scope Images
PV system drawing example
PV system drawing example
Scope

Provide an architectural drawing and riser diagram for the homeowner showing the planned location for future photovoltaic and solar hot water system components.  Space requirements and layout for photovoltaic and solar water heating system components should be taken into account 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 meet the requirements of the DOE Zero Energy Ready Home program, provide an architectural drawing and riser diagram of RERH solar PV system components and solar hot water.

Develop architectural drawings and diagrams that summarize the installed system equipment (conduit, etc.) as detailed below (see Figure 1). These drawings should accurately represent the installed elements of the system and should be provided to the homeowner (likely to be used by future solar installer for obtaining a building permit).  In addition, the homeowner should be provided with a one-line electrical riser diagram of the PV system components. The diagram should have sufficient detail to clearly identify:

  • Configuration of the PV array
  • Conduit size and type
  • Electrical service panel location and dedicated circuit breaker slots
  • Length of conduit from the designated array location to the designated inverter location
  • Location and number of necessary pull boxes in line with each conduit run
  • Length of conduit from the designated inverter location to the electrical service panel
  • Location of the Balance-of-System (BOS) components

The drawings should also contain information about the PV array mounting system and identify the specifications for the major equipment including manufacturer, model and installation details.

PV system drawing example
Figure 1. PV system drawing example.

When designing the system, always follow the recommendations of all local and national codes as well as manufacturer’s recommendations.

Ensuring Success

Ensure adequate utility room early in the house design process to allow for ample space for solar photovoltaic (PV) and water heating system components.  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. 
Map of average daily solar radiation
Map of average daily solar radiation
Presentations
CAD

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)

Provide architectural drawing of solar PV system components. (RERHPV Guide 3.5)

Alternative: Provide home buyer with the following information:

  • List of renewable-ready features
  •  Available free roof area within +/- 45° of true south
  • Location of panel or blocking for future mounting of PV system components
  • Location of Breaker or slot for future breaker in electrical service panel
  • Copy of the PV-Ready Checklist
  • A copy of the RERH Solar PV Specification Guide

Footnote 18) DOE Zero Energy Ready Home requires that the provisions of the PV-Ready Checklist are completed based on the requirements and allowances in this end note. 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. DOE encourages, but does not require, the use of the Solar Water Heating-Ready provisions.

The PV-Ready Checklist only applies when all of the following conditions 1 through 4 below are satisfied. Homes for which the PV-Ready Checklist does not apply based on these criteria may still qualify for DOE Zero Energy Ready Home if all other program requirements are satisfied. Homes that utilize renewable energy from utilities or third parties on a contractual basis may also be exempt from the PV-Ready Checklist – contact DOE for further guidance.

  1. The home does not already include a PV system. This includes installed community solar systems which contribute some amount of offset to the home’s electrical usage.
  2.  Location, based on zip code, has at least 5 kWh/m2 /day average daily solar radiation based on annual solar insolation using this online tool: PVWatts Calculator. Users should enter the project location zip code, use the System Info default settings, and then proceed to the “Results” tab on the tool to see the Average Annual Solar Radiation value in kWh/m2 /day.
  3. Location does not have significant natural shading (eas designed has the minimum free roof area within +/- 45◦ of true south as noted in the table below. Note that in some cases a house may have insufficient roof area for the Solar Electric RERH checklist, but it may still have the minimum roof area for the solar thermal RERH Checklist and would therefore have to comply with the Solar Thermal RERH checklist. In other cases, the home may only have adequate south facing roof for the Solar Electric or Solar Thermal RERH Checklist, but not both. In that case the builder can decide which one of those two checklists to apply (e.g., trees, tall buildings on the south-facing roof).
  4. Home as designed has the minimum 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, and 2018 International Energy Conservation Code (IECC)

Section R401.3 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: 

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.)

2009, 2012, 2015, and 2018 International Residential Code (IRC)

M2301 Solar Energy Systems (Solar Thermal Energy Systems in 2015 and 2018 IRC)  - See requirements for solar water heating systems.

Retrofit: 

2009, 2012, 20152018, 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.)

Appendix J regulates the repair, renovation, alteration, and reconstruction of existing buildings and is intended to encourage their continued safe use.

List of National Fire Protection Agency (NFPA) Codes & Standards and the 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.

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)
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.
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)
Building Science Corporation
Organization(s)
Building Science Corporation
Publication Date
Description
Report aiming to "de-mistify" technology and economic considerations of residential PV systems.
Author(s)
Aldrich
Organization(s)
CARB,
Steven Winter Associates,
SWA
Publication Date
Description
Brochure on specifications for PV systems.
Author(s)
National Renewable Energy Laboratory
Organization(s)
NREL
Publication Date
Description
Website that estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations.
Author(s)
National Fire Protection Association
Organization(s)
NFPA
Publication Date
Description
This standard provides a benchmark for safe electrical design, installation, and inspection to protect people and property from electrical hazards and has been adopted in all 50 states.
Author(s)
U.S. Environmental Protection Agency
Organization(s)
EPA
Publication Date
Description
Website providing the technical specifications and related documents for home builders, subcontractors, architects, and other housing professionals interested in certifying a home to the EPA's Indoor airPLUS program requirements.
*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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