Friday, June 8, 2012

Ready, Solar, Go

Hello Mr. Gomez

I'm impressed with the new building efficiency standards and in particular the Solar Ready roof requirement. Can you tell me what the Solar Ready roof requirement costs are per home or business? Is this information broken out in the analysis?


Dear Photomofo,

The final version of the solar ready requirements (Section 110.10 of the 2010 Building Energy Efficiency Standards) may be viewed at  The attached errata includes changes in grey highlight.

The solar ready requirements are really for a reserved piece of roof space that isn’t self-shaded by other features on the building. There are no ‘infrastructure’ type items such as conduit/piping, collateral structural loads, or pre-installed mounting hardware, thus costs are expected to be minimal to none.

For single family homes, the solar ready requirements are applicable to subdivisions with 10 homes or greater. The cost that single family homes built in 2014 would incur to make them “solar ready” was calculated to be $182.  The primary report relied upon for the development of the “Solar Ready Roofs” requirement for single family homes was done by the California Utilities State Wide Codes and Standards Team (CASE).  You can find this report in its entirety at For single family homes there is a requirement for a 200 amp bus bar and spare breaker space opposite of the main breaker/service conductors, which resulted in the $182. The $182 is averaged across expected single family housing starts. For the approximately 80% of homes that would already be designed to have a 200 amp bus bar or electrical service, the actual costs would be less. For the 20% of homes where the 200 amp bus bar or electrical service would be considered an ‘upgrade’, the actual costs would be higher. This is detailed in the CASE report. 

The report for nonresidential buildings can be found at  While there was an added cost determined for single family homes, there was no added cost for nonresidential buildings.  Below is an excerpt from this report explaining why.

From the Nonresidential Solar-ready Building Report done by the California Utilities Statewide Codes and Standards Team

3.5 Cost Effectiveness Methodology
The proposed code change does not require equipment installation nor does it have any incremental
maintenance costs. The only costs associated with the measure are design costs. Initially designers
will need to familiarize themselves with the solar-ready requirement, but over time design will
become streamlined and the costs will be minimal. The LCC Methodology does not include design
costs in the costs of a measure, so for LCC purposes the measure has no costs.

A list complete with links for all documents relied upon for the development of the 2013 Building Energy Efficiency Standards can be found at

If you have any further questions, feel free to email back at the hotline email address below, or contact us by phone at (800) 772-3300.

Best regards,

Javier Perez
Energy Standards Hotline Staff
California Energy Commission
1516 Ninth Street
Sacramento, CA 95814


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