If you’re building a new home in California, you’re getting solar, thanks to the landmark Title 24 mandate. However, the solar system your builder installs may be designed to meet a minimum legal requirement, rather than your family’s actual energy needs.
But here’s the crucial question for new homeowners: Does simply meeting the code guarantee you’re getting the best, most cost-effective solar system for your family’s future? The answer, surprisingly, is often no.
What is California’s Title 24 Solar Requirement?
California’s Title 24 mandate is not just one law; it’s a comprehensive set of building codes that governs nearly all aspects of construction, from insulation and windows to lighting and, most recently, on-site energy generation. The energy efficiency portions are updated every three years by the California Energy Commission (CEC) to ensure buildings reduce wasteful and unnecessary energy use.
The landmark solar mandate, adopted as part of the 2019 California Energy Code and taking effect on January 1, 2020, requires that all new low-rise residential buildings (single-family homes, duplexes, apartments up to three stories) must include a solar photovoltaic (PV) system.
The Core Requirement
The mandate is designed to ensure that the installed solar system is sized to offset the home’s projected annual electricity usage. The system size is not a one-size-fits-all number. It is calculated based on several factors:
- Climate Zone: California has 16 distinct climate zones, and the expected energy use varies significantly between them (e.g., a hot inland zone requires a larger system than a mild coastal zone).
- Conditioned Floor Area (CFA): The size of the living space in square footage.
- Energy Efficiency Measures: The efficiency of the home’s overall design which can reduce the required solar system size.
Builders typically use a calculation, often referred to as the Prescriptive Method, to determine the minimum solar system size required for compliance.
Why the Minimum Might Not Be Enough
While Title 24 is a monumental step toward a cleaner energy future, homeowners need to understand that compliance is not the same as optimization. The systems installed by builders are designed to meet the minimum legal requirement, which might not align with a homeowner’s real-world energy goals for two key reasons: Electrification and Lifestyle.
1. The Electrification Evolution
The Title 24 calculation for the minimum solar size is based on a set of assumptions that may not account for a homeowner’s future plans.
- Electric Vehicle (EV) Charging: A growing number of new homes will have an EV, or multiple EVs. Charging even one EV at home can add hundreds of kilowatt-hours per month. The minimum mandated solar system will almost certainly not be sized to cover EV car charging.
- Electric Appliances: While many new homes are moving toward all-electric designs, the calculation often assumes a “mixed-fuel building” with natural gas for heating and water. If you convert your home to a fully electric heat pump HVAC and water heating system, a common and highly efficient upgrade, your electricity needs will spike, leaving the minimum system undersized.
2. Family Size and Lifestyle
The CEC’s calculation uses a fixed assumption about how much energy a typical family in that sized home will use. However, your actual energy use is unique:
- Working from Home: Families with one or more members working from home use significantly more electricity during daylight hours than the average commuting family.
- Pool or Spa: Operating a pool pump or heating a spa uses a substantial amount of electricity.
- Larger System for Zero Bill: Homeowners often seek a system that generates enough power to cover 100% or more of their usage to achieve a near-zero utility bill. The Title 24 mandate is only designed to offset the expected usage, and any major deviation (like those listed above) will lead to higher-than-expected utility bills.
In short, meeting the Title 24 requirement is a fantastic starting point, but it’s often a case of the builder’s minimum versus the homeowner’s maximum savings. Contacting your local solar installer, like OC Solar, is the best way to ensure accurate system sizing.
The Storage Imperative: Moving Beyond Just Panels
Although Title 24 primarily focuses on solar panels, homeowners in California now face utility rate structures that make battery storage equally important. While not always strictly required for a low-rise home to achieve Title 24 compliance, batteries are essential for maximizing solar savings under the current utility rate structures, particularly the latest shift to Net Energy Metering (NEM 3.0).
A battery allows you to store the solar energy you generate during the low-demand midday hours and use it during the high-cost Time-of-Use (TOU) peak hours in the late afternoon and evening. Modern batteries like the Tesla Powerwall 3 and Enphase 5P or 10C allow homeowners to store excess energy and avoid buying electricity when rates are highest. This is the difference between simply having solar and having an optimized, money-saving energy solution.
Final Thoughts
Title 24 is a strong starting point for clean energy in Southern California, but it is not a one-size-fits-all solution. The minimum solar requirement helps new constructions meet statewide efficiency goals, but it rarely aligns with the real energy needs of a modern household. Whether you already live in a Title 24 home or are preparing to build one, taking the time to design a system based on your lifestyle gives you better savings, more comfort, and greater long-term value.
Ready to Go Beyond the Minimum?
If you want a solar system that truly matches your energy use, OC Solar can help. Our team designs custom systems for homeowners across Southern California, offering high-performance solar panels, batteries, and complete turnkey installations.
Contact OC Solar today to schedule a free custom solar evaluation and discover how much more you can save with the right system!