Solar and Net Zero Homes Under California Title 24: What the 2022 Mandate Actually Requires in 2026

What Title 24 Actually Requires for Solar and Batteries

California's Title 24, Part 6 is the state's Building Energy Efficiency Standards. It governs energy use in all new construction and major renovations in California. The 2019 edition of Title 24, which took effect January 1, 2020, was the first to mandate solar photovoltaic systems on new single-family homes and low-rise multifamily buildings. California was the first state in the country to adopt a statewide solar mandate for residential construction.

The mandate requires a solar system sized using the California Energy Commission's compliance software. The software calculates a minimum system size based on three variables: the home's conditioned floor area, the climate zone where the home is located, and adjustments for shading and roof orientation. The formula is designed to produce a system that offsets a modeled average household's energy consumption under a standardized load profile.

For a 2,400 square foot home in Riverside County's climate zone (zone 10 or 15, depending on specific location), the compliance calculation typically yields a minimum solar system of 2.5 to 4.0 kW DC. That is the floor. Builders may install larger systems, but they are not required to. Most builders install exactly what the compliance calculation requires, no more.

Title 24 is an efficiency floor, not a performance guarantee. Meeting the code means your home satisfies minimum state requirements. It does not mean your electricity bill will be low, let alone zero.

How the 2022 Title 24 Update Changed the Rules Versus 2019

The 2022 Title 24 standards, which took effect January 1, 2023, made three meaningful changes to the solar and energy requirements for new residential construction. Understanding these changes is essential for buyers of homes permitted after that date, which includes virtually all new construction in Temecula communities opened in 2023 or later.

Change 1: Mandatory Battery Storage

The 2019 standards required solar but did not mandate battery storage. The 2022 update added a battery energy storage system requirement for most new residential construction. The minimum battery size is calculated by the CEC's compliance software based on the home's conditioned floor area, climate zone, and proposed solar system size. For a typical 2,400 square foot home in Riverside County, the compliance minimum typically falls between 3 and 7.5 kWh. This is a small battery by performance standards but represents a genuine policy shift: California now requires homes to have on-site storage, not just on-site generation.

Change 2: Tightened Building Envelope Requirements

The 2022 standards introduced stricter requirements for insulation, windows, air sealing, and cool roofs. A better-insulated, tighter home needs less energy to condition, which reduces the heating and cooling load the solar system must cover. In theory, a more efficient building envelope slightly reduces the solar minimum for a given home size. In practice, this reduction is modest and is more than offset by the new battery requirement and the tightening of other energy end-use requirements.

Change 3: Stronger All-Electric Incentives

The 2022 standards significantly improved the compliance pathway for all-electric homes versus mixed-fuel homes. A home with no natural gas appliances, using heat pumps for space conditioning and water heating and induction or electric cooking, meets 2022 Title 24 compliance more easily and at lower compliance cost than an equivalent home with gas appliances. This creates a strong regulatory incentive for builders to go all-electric. Most new construction in Temecula communities opened after 2023 defaults to all-electric, which has direct implications for solar sizing, discussed in section four.

Net Zero Energy vs. Net Zero Bills: Why They Are Not the Same

This distinction matters more than almost any other concept in this guide. Builders and solar salespeople use "net zero" loosely, and the ambiguity costs homeowners money.

A net zero energy home, as defined by the Department of Energy and the California Energy Commission, produces as much total energy over the course of a year as it consumes. The measurement is typically in kilowatt-hours. If your home consumes 12,000 kWh in a year and your solar system produces 12,000 kWh, you have a net zero energy home by this definition.

A net zero bill means your annual electricity charges, after all solar credits and utility fees, total zero. Under California's NEM 3.0 net metering rules, this is significantly harder to achieve than net zero energy, even with the same kilowatt-hour balance.

Here is why. Under NEM 3.0, SCE credits solar electricity exported to the grid at avoided cost rates, which average 4 to 8 cents per kWh depending on the time of day. SCE charges for electricity imported from the grid at retail rates, which range from 28 to 55 cents per kWh depending on the rate plan and time of day. The asymmetry is severe. You might export 1,000 kWh and earn $50 in credits, then import 1,000 kWh and owe $400 in charges, for a net bill of $350 on a technically net zero energy balance.

The conclusion is straightforward. Achieving a net zero bill under NEM 3.0 requires minimizing grid imports, especially during peak hours. The way to minimize peak imports is to store solar production in a battery during the day and discharge it during the 4 pm to 9 pm peak window. A solar system without battery storage, even one that is technically energy-balanced on a yearly basis, will generate a meaningful SCE bill under NEM 3.0 because of timing mismatches between solar production and household consumption.

The phrase "net zero home" in a builder's marketing should always prompt the question: net zero energy or net zero bill? If the answer is energy only, ask what the projected annual SCE true-up payment is expected to be. If the sales rep cannot answer that question, the system is not designed for bill minimization, only for code compliance.

The All-Electric Home Equation: How Heat Pumps and EVs Raise the Solar Sizing Bar

California's regulatory framework is driving new homes toward full electrification. The 2022 Title 24 standards, combined with the California Air Resources Board's phase-out of gas appliance sales and local reach codes in many municipalities, means the majority of new homes in Temecula communities built after 2023 are all-electric by design.

This creates a math problem that most builder solar packages do not solve. When a home eliminates natural gas and replaces every gas appliance with an electric equivalent, total electricity consumption rises significantly, even though the home may be more energy-efficient on a BTU basis. Heat pump technology is more efficient than gas combustion for the same amount of useful heat delivered, but efficiency does not reduce the electricity demand, it just means less waste.

Heat Pump Space Conditioning

A heat pump replacing a gas furnace in a 2,400 square foot Temecula home adds approximately 1,500 to 2,500 kWh per year in electricity consumption for heating. Cooling with a heat pump is comparable to a traditional air conditioner, so cooling loads remain similar. The net addition is primarily the heating season electricity. In Temecula's mild climate, this is a smaller addition than in colder areas, but it is not negligible.

Heat Pump Water Heating

A heat pump water heater (HPWH) is significantly more efficient than a gas water heater, using roughly one-third the energy in BTU terms. However, it runs on electricity rather than gas, adding 1,000 to 1,500 kWh per year to electricity consumption while eliminating the equivalent gas usage. For a homeowner replacing gas with electric, the net effect is positive on the gas bill but adds to the solar sizing requirement.

EV Charging

A single electric vehicle driven 12,000 miles per year consumes approximately 3,000 to 4,000 kWh annually when charged at home. A two-EV household adds 6,000 to 8,000 kWh. This is often the largest single variable in residential solar sizing decisions, and it is consistently absent from the Title 24 compliance calculation because the code standardizes on a hypothetical household with no EV loads.

The gap between a Title 24 compliance minimum of 3 to 4 kW and a true net zero sizing of 10 to 14 kW is substantial. That gap represents thousands of dollars in annual SCE charges that a homeowner expecting a "net zero" home will be surprised to owe.

Battery Storage Requirements for New Construction in 2026

California's 2022 Title 24 standards made battery energy storage a mandatory component of new residential construction for most home types in most climate zones. This represented a significant expansion of the 2019 mandate, which required only solar. Understanding what the battery requirement actually requires, and what it does not, is critical for buyers evaluating new construction.

How the Minimum Is Calculated

The minimum battery capacity is calculated by the CEC's compliance software using the home's conditioned floor area and the solar system size. For a typical 2,400 square foot home in Riverside County, the compliance minimum typically falls between 3 and 7.5 kWh of usable battery capacity. The calculation is designed to enable demand flexibility and grid services, not to provide meaningful home backup during an outage.

What the Compliance Minimum Delivers

A 3 to 7.5 kWh battery can power essential circuits for 2 to 6 hours depending on load. A refrigerator running continuously draws 100 to 200 watts. A few lights and phone chargers add perhaps another 200 watts. At 500 watts total load, a 5 kWh battery provides 10 hours of runtime. However, if you add an air conditioner, a water heater, or any significant appliance, runtime collapses. A 5-ton central air conditioner draws 3,500 to 5,000 watts. At that load, a 5 kWh battery provides less than 2 hours.

What Whole-Home Backup Actually Requires

A battery sized for meaningful whole-home backup, covering critical loads for 8 to 24 hours during a PSPS event or wildfire-related outage, typically requires 10 to 20 kWh of usable capacity. A Tesla Powerwall 3 delivers 13.5 kWh of usable capacity. An Enphase IQ10T delivers 10.5 kWh usable. Two stacked units of either product provide the 20+ kWh range suitable for overnight backup with modest loads.

Local Reach Codes May Require More

Some jurisdictions within California have adopted local reach codes that exceed state minimums. Certain fire-hazard severity zone areas, including some communities in the Santa Ana Mountains near Temecula, have adopted or are evaluating codes requiring larger battery systems than the Title 24 state minimum. If you are buying in a community designated as a high fire hazard severity zone, check whether the local jurisdiction has adopted any reach code requirements beyond the state baseline.

What Sommers Bend and Other Temecula New Developments Are Required to Install

Every new single-family home permitted in Temecula after January 1, 2023 must comply with the 2022 Title 24 standards, including both the solar and battery requirements. This applies to every home in Sommers Bend, Altair, Heirloom, and any other active new construction community in the city.

HERS Testing: What It Is and What It Means for Buyers

HERS stands for Home Energy Rating System. A HERS rating is conducted by a California-certified HERS rater, an independent third-party professional who physically tests the home and verifies that the as-built construction matches the compliance documentation submitted to the building department.

What HERS Testing Involves

A complete HERS rating for a new California home includes several physical tests. A blower door test measures air leakage in the building envelope, confirming that the home is sealed to the level assumed in the compliance calculations. A duct leakage test measures leakage from the HVAC duct system. The rater also performs a visual verification that insulation, windows, and HVAC equipment match the specifications in the compliance documentation. For solar, the rater verifies that the installed system size, panel orientation, and inverter type match what was modeled for compliance credit.

The HERS Index Score

A HERS index score is produced after testing. The score is referenced against a 2006 energy code baseline home of the same size and type. A score of 100 equals the 2006 baseline. A score of 50 means the home uses 50 percent of the energy of a 2006 baseline home. A score of 0 means net zero energy. A score below 0 means the home is a net energy producer, generating more than it consumes.

Most homes built to 2022 Title 24 standards achieve HERS scores between 20 and 60, with the range depending on the solar system size, battery, building envelope performance, and mechanical systems. A home achieving HERS 0 or below is genuinely net zero energy by the DOE definition. A home with HERS 40 uses 60 percent of the energy of a 2006 baseline but is not net zero.

What Buyers Should Ask About HERS

Any builder making net zero or near-net-zero claims should be able to provide a HERS certificate from a certified rater confirming the as-built home's score. A compliance model output printed from the CEC's software is not the same as a verified HERS rating. The compliance model is based on design drawings. The HERS rating is based on the physical home after construction. The two can differ if construction does not match the design documentation.

Ask for the HERS certificate and the HERS index score before closing. Ask whether the score assumes the solar system produces at the modeled level or whether it is based on measured production. Ask what the score would be if the solar system were sized for your actual load rather than the compliance minimum.

How to Size a System for a True Net Zero Outcome, Not Just Code Compliance

Sizing a solar and battery system for a true net zero outcome requires starting from your actual household's annual electricity consumption, not from the Title 24 compliance formula. The process involves four steps: estimating total annual consumption, accounting for future loads, designing solar to cover that consumption profile, and sizing battery storage to minimize peak imports.

Step 1: Estimate Your Actual Annual Consumption

Start with your current SCE bills if you are moving from an existing home. Add the electricity loads for any appliances or loads you are replacing or adding: EV charging, heat pumps, pool pump. If you are moving from a different climate zone, adjust for Temecula's heating and cooling patterns. A licensed solar installer can pull historical production data from comparable homes in the same climate zone to validate estimates.

Step 2: Size the Solar Array for That Consumption

Divide your estimated annual consumption in kWh by the average peak sun hours in your location times 365 days and an efficiency factor. For Temecula's climate zone, peak sun hours average 5.2 to 5.8 hours per day. A rough rule of thumb: divide your annual kWh target by 1,500 to 1,700 to get the approximate kW DC system size needed. For 15,000 kWh annually, that suggests a 9 to 10 kW system. For 20,000 kWh, the result is 12 to 13 kW.

Step 3: Size the Battery for Peak Management

Under NEM 3.0, the battery's job is to store afternoon solar production and discharge it during SCE's peak rate period, 4 pm to 9 pm. Most households in Temecula draw 500 to 1,500 watts of continuous load during evening hours before the peak window ends. A 10 to 15 kWh battery provides 5 hours of 2 to 3 kW average load coverage, which is typically sufficient to get through the peak window without grid imports. If you have a pool pump running evenings or plan to charge an EV in the 4 to 9 pm window, size up accordingly.

Step 4: Account for EV Charging Strategy

Charging an EV during peak hours, 4 pm to 9 pm, is expensive under SCE's time-of-use rates. Setting your EV to charge after 9 pm, during off-peak hours, reduces the battery sizing requirement for net zero because the EV is not competing with the battery during the peak window. An EV charger with scheduling capability, combined with an SCE TOU rate plan and a properly sized solar and battery system, is the optimal configuration for minimizing total annual electricity costs.

Phased Net Zero Upgrades for Existing Homeowners

Net zero is not only a new construction concept. Existing homeowners in Temecula, Murrieta, Menifee, and throughout Riverside County can upgrade their homes toward net zero energy incrementally over time. The key is sequencing upgrades correctly to avoid cost duplication and to ensure the solar system is sized for the eventual end state, not just today's load.

Key Questions to Ask Before Buying a New Construction Home

Use this list before signing any purchase agreement. Every answer should come in writing, either in the contract or a signed addendum.

Frequently Asked Questions