California Rooftop Solar Mandate Leading Nation by Example

January 9, 2019
Car near field at sunrise
Photo: Unsplash/Benjamin Shanks

In 2020, California's rooftop solar mandate for all newly built single-family homes in the state goes into effect, and experts anticipate it will help normalize the use of solar nationally in residential construction

California is the first state to have such a mandate in its building codes, applying to its roughly 80,000 new homes built every year. The code also requires greater efficiency measures including thicker insulation and tighter sealing doors, and spurs on developers to add onsite battery storage and solar-powered water-heating systems on the roof. In terms of cost, developers now take on the cost of sourcing and installing the solar array, an average $9,500 per home. In turn, homeowners' have an average $40 added to their monthly mortgage, while saving $80 per month in energy and maintenance costs, Fast Company reports. 

Lennar, a residential developer based in California but with projects across the country, already has a formula down. In 2012, Lennar built out a solar subsidiary, SunStreet, which specializes in integrating solar into the home construction process. Rather than retrofitting a solar array onto a roof, which entails an installation and wiring process, SunStreet builds the array into the roof and connects it to the electrical system as the construction is under way. This model, Knutsen says, will be something for builders and solar providers alike to look to as they adapt. David Kaiserman, SunStreet founder and Lennar president, says that his ventures are planning to offer guidance to other developers and solar providers looking to streamline solar integrations going forward.

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