In May of 2018, the California Energy Commission (CEC) approved the latest edition of the state’s building energy efficiency standards which are designed to reduce unnecessary consumption of energy in newly constructed buildings. The 2019 efficiency standards, known as Title 24, Part 6, are a part of the California Code of Regulations and went into effect on January 1, 2020.
The “Solar Mandate” is the latest edition to the California energy code which introduces the requirement for photovoltaic (PV) systems to be installed on all new low-rise residential buildings. This includes single-family homes as well as multi-family homes up to 3-stories.
The energy savings from the 2019 efficiency standards is estimated to be 53% less than homes built under the 2016 standards. With 80,000 new homes built in California each year, greenhouse gas emissions will be reduced by 700,000 metric tons over three years, which is equivalent to taking 115,000 petroleum-based cars off the road.
The photovoltaic system requirement is the latest step towards California’s zero-net-energy goal. It builds upon the 2013 code that required new subdivisions of 10 or more homes to be constructed “solar ready.” A new “solar ready” home must include allocated space for a minimum 250 sq-ft unshaded, obstruction-free, “solar zone.”
Zero-net-energy buildings utilize energy efficiency elements to limit energy consumption to match the energy they generate from renewable energy sources, such as solar or wind. The new photovoltaic requirement section specifies that all new low-rise residential buildings shall have a PV system with an annual electrical output greater than or equal to the dwelling’s annual electrical usage. It is important to note that these standards do not yet mandate zero-net-energy compliance as other forms of fuel, such as gas, can be incorporated into the new construction.
How Much Solar?
The minimum system size is based on the home’s square footage and location (climate zone), and is determined by the equation:
kWPV = (CFA x A)/1000 +(NDwell x B)
kWPV = kWdc size of the PV system
CFA = Conditioned floor area
NDwell = Number of dwelling units
A = CFA adjustment factor
B = Dwelling adjustment factor
Determine your basic PV system size: California Solar Mandate Calculator
There are 16 unique climate zones established by the California Energy Commission with energy budgets based on local energy use, temperature, and weather. The CEC climate zone map along with the Conditioned Floor Area (CFA) and dwelling adjustment factors for each zone are shown below.
Find your climate zone: Climate Zone Locator
Example PV size calculation:
What is the minimum PV system size (kW) required for a 2100 sq-foot single-family home located in Mountain View, CA (climate zone 3)?
(2100 x 0.628) / 1000 + (1 x 1.12) = 2.44 k
Exceptions to the minimum PV system size calculation are provided to adjust the required system size based on various attributes such as climate zone, habitable stories, and annual solar access.
A notable exception is that the required PV system size can be reduced by 25% when coupled with a battery storage system with a minimum capacity of 7.5kWh.
Read how exceptions affect the PV system size: The California Solar Mandate: How to Calculate
The CEC estimates the additional up-front cost for the mandated solar is approximately $8,400. This works out to about $40 more per month over the life of a 30-year mortgage.
The new energy standards are estimated to save new homeowners about $80 per month on their heating, cooling, and lighting bills.
Some real estate market experts are concerned that the added cost of mandated solar will push homeownership beyond the reach of many new buyers. Others believe that the up-front increase will only affect a small, less than 1%, segment of new home buyers.
This latter opinion seems to be substantiated by early solar adopters in the building industry that report no slow down in sales of new homes pre-built with a PV system.
System Sizing ToolsTo find out how much PV you will need under the new mandate, check out our California Solar Mandate Calculator and Climate Zone Locator.
If you need help getting started, you can watch our video tutorial on how to use the Solar Kit Guide, or contact the Renvu sales team at firstname.lastname@example.org or 855-755-5855.