This post was written by Josh Weiner, Solar Expert Witness & Solar Engineering Expert. Mr. Weiner has been at the forefront of the solar energy industry for over 20 years and is an industry leader on solar-plus-storage engineering & design. Josh’s expertise spans both in-front of and behind-the-meter initiatives including residential, commercial, utility, grid-scale, and ev charging solar and storage applications. 

If you’re an architect, new homebuilder or housing developer in California, you’ve probably heard by now that the California Energy Commission (CEC) has updated its Title 24 solar and energy efficiency standards. Effective January 1, 2020, the update specifically mandates that all new California homes under three stories install solar panels on the roof or achieve an equivalent total home energy efficiency reduction through other measures.

To comply with Title 24, new homebuilders, architects and developers will be required to use Title 24’ssoftware for calculating the building’s “Energy Design Rating” (EDR), which not only includes inputs for solar but also for energy storage and other options.

To give builders more flexibility, the EDR is scored like a golf tournament—the lower the score, the better (or, the more “energy efficient” the home is). The goal is to achieve an equal-to-or-less-than EDR for a solar home than a comparable “regular” home, of the same square footage.

Depending on the square footage and climate, new-home solar will range between 2.7 and 5.7 kW DC to meet the requirements, but that doesn’t tell the whole story. Rather than meeting the minimum requirements, builders may be better off designing their Title 24 solar systems with battery storage.

Why Builders Should Include Storage with Solar

As mentioned, the EDR software gives homebuilders a score, but there are many ways to meet that score, and one is combining solar with energy storage. Including energy storage will not only meet the minimum solar requirements, but will maximize energy savings for the home, offering customers a financial advantage over other homes.

When solar engineers design a solar system, they typically take into consideration the following factors:

• The climate
• The average amount of sunlight for the area
• The orientation of the roof in relation to the sun
• The amount of potential shading over the course of the year
• The pitch of the roof
• The home’s annual kWh usage

While these parameters are important, equally important are the utility rate considerations that system designers like SepiSolar factor into their plan sets. These rate policies affect the solar system’s ROI and include:

•  Tiered Rates. Tiered rates vary by utility and charge customers higher rates when they use more energy over a certain monthly amount.
• Net Energy Metering (NEM). NEM is like rollover minutes for solar. Utilities will credit solar homeowners for any excess solar power that is exported to the grid. The value of NEM varies by the utility and the time of day that the solar is exported to the grid.
• Time of Use (TOU). TOU rates also vary by utility. Customers incur charges when they use grid energy. During peak times, such as rush hour when the sun is setting and people are coming home, utilities charge solar and nonsolar homeowners a higher rate when they draw power from the grid, making any exported solar energy less valuable during that time of day.

That’s where energy storage (batteries) comes in.

Designing Systems for Overall Cost Savings for Solar and Title 24

Due to the above utility rate considerations, home developers that want to design premium homes that maximize utility savings as well as comply with the Title 24 solar mandate should consider including energy storage systems with their solar designs.

Solar+storage with smart battery management software will counteract the cost of tiered rates and TOU through “load shifting,” and “peak shaving.”

With peak shaving, homes using solar+storage will be able to use as much free solar as they can during the highest TOU rates while saving the excess energy in their batteries instead of exporting to the grid. Then, during peak TOU periods, the home will use this free stored solar-generated energy when the utility rates are high.

Additionally, battery management systems can also “load shift” the time when appliances are turned on or off, such as turning on a dishwasher, dryer or charging an EV when utility rates are low or when electricity can be drawn from the battery that was charged by solar.

Both peak shaving and load shifting with solar+storage encourage the home to use more of its own self-generated power, relying less on importing power from the grid. With so many homes using solar after 2020, homeowners with solar+storage will also help stabilize the grid, and can be paid a higher credit for any power the utility draws from the storage system during peak hours.

Another sales advantage for developers is that solar+storage offers some emergency power in case of a blackout. That is not the case with stand-alone solar PV systems. To protect power line repair workers, stand-alone solar systems will automatically shut down during an outage.

Things to Keep in Mind About Solar+Storage with Title 24

If you decide to meet your Title 24 solar mandate with energy storage, there are several requirements to keep in mind.

First, when adding storage to solar, there is a minimum required battery size of 5 kWh. This is a reasonable size that will allow for taking advantage of tiered rates and TOU, and it will provide a minimal amount of backup power in case of an outage.

Second, your solar+storage system designer and engineer will have to select one of three control options for the battery:

• Option 1 – Basic Control (Title 24, Section JA12.2.3.1): With Basic Control, the battery system can only be charged by the solar system and can only discharge when there’s not enough solar power to meet the home’s current energy usage.
• Option 2 – TOU Control (Title 24, Section JA12.2.3.2): With TOU Control, battery system will be set up with Basic Control, but will only discharge during the peak TOU hours of the day. This will change from season to season, and must be configured from the battery manufacturer or programmed by the installer at the time of commissioning.
• Option 3 – Advanced Demand Response Control (Title 24, Section JA12.2.3.3): With this configuration, solar+storage systems will be programmed with Option One or Two. In addition, the battery control system must meet the demand-response requirement of a utility or third-party owner; that is, the utility or third party will be able to remotely control when the battery is charged and discharged. Typically, the homeowner will receive a financial benefit for this utility interaction with the grid.

The rules within each category will most likely be refined over time, so it’s important for your solar designer to be up to date with these standards and make any necessary changes. The above is a summary, so please review the entire Joint Appendix 12 to take full advantage of the above credits.

As longtime solar+storage engineers with thousands of projects, SepiSolar has a great deal of experience designing solar and battery systems that meet the new Title 24 regulations, as well as designing systems that comply with the local requirements of counties and other local authorities having jurisdiction (AHJs). Please contact us if you have any questions about these new Title 24 solar requirements for your new residential solar development projects.