Data Corner: Getting to Know Stockton and Lathrop, in an Energy Way

Ava will begin service in Stockton and Lathrop this year. To get to know our newest cities, we did a brief data analysis of how energy demand, solar adoption, and electric vehicle use varies in the Valley.

Ava has welcomed the cities of Stockton and Lathrop as new members, with service starting in April 2025. Unincorporated areas of San Joaquin County will start service in 2026.

This expansion into the Central Valley helped prompt a name change, from East Bay to Ava. But it also has implications for Ava’s energy service.

Hot summers in the Central Valley are very different from the East Bay’s mild Mediterranean climate. Homes in the Valley rely much more on air conditioning to keep cool in the summer, driving up electricity demand. 

This promises to make Ava’s overall energy profile more seasonal, with bigger peaks on hot summer afternoons and evenings. Bigger peaks mean greater need for capacity (known as resource adequacy) and a better alignment with summer solar power generation.

The Valley also has some new energy opportunities. There is more room for solar farms, a newer and expanding stock of buildings, an opportunity to help decarbonize agricultural industries (like energy-intensive water pumping), and converting the large fleet of gasoline vehicles currently on the road.

To get to know our new members—in an energy way—we have compiled a number of interactive data dashboards covering energy consumption, solar power, and electric vehicles.

Since Stockton will be Ava’s second largest city, we decided to compare residential energy use in Stockton—in the hot Central Valley—to Ava’s largest member, Oakland, on the Bay.

As shown in the interactive graphic, the very different summer climates drive a boom in residential electricity demand in July and August, with the average Stockton household consuming up to five times as much power as the average Oakland home. This drives a commensurate boost in summer utility bills.

The chart at the bottom of the graphic shows that Oakland electricity demand is nearly flat year round, even slightly lower in the summer. Stockton demand is about the same as Oakland most of the year, with the huge exception of July and August. 

The line on the chart indicates “degree days,” a measure of how weather drives heating or cooling demand. A degree day is the average temperature above or below 60°F for a day. Degree days above 60°F are cooling degree days, those below are heating degree days.

So if a summer day has an average 24-hour temperature of 80°F, it counts as 20 cooling degree days. If a week in the winter has average daily temperatures of 50°F, it counts as 70 heating degree days (7 days x 10°F per day).  

The spike in cooling degree days in the summer very clearly drives the increase in electricity demand in Stockton, as shown by the bars. Generally higher electricity demand in Stockton homes year-round could be due in part to the different home types: Stockton has more single-family freestanding houses, while Oakland has more apartment buildings, which tend to be more energy efficient.  

One unknown shows up on the natural gas tab. We can see that winter demand for space heating is almost identical across the two cities, while summertime demand is higher in Oakland for some reason. Is this due to more hot showers in Oakland in the summer, or more cold showers in Stockton?

To put it in context, the differences between Stockton and Oakland are mild compared to the heat of Phoenix and the cold of Chicago, as shown in this bonus chart. Summer cooling needs in Phoenix are 2.5 times greater than in Stockton, while Chicago in January sees almost triple the heating degree days.

California has a number of energy programs designed to reduce the financial burden of utility bills. The most prominent are the California Alternate Rates for Energy (CARE) and the Family Electric Rate Assistance (FERA) programs. CARE offers a 30-35% discount on electric bills and a 20% discount on natural gas bills. FERA offers an 18% discount on electricity bills for qualified households of three or more people. The cost of these programs is absorbed in the rates of the three investor-owned utilities.

Adding Stockton and Lathrop will boost the number of Ava customers on CARE and FERA rate discount plans by 40% to a new total of 173,586.

As shown in the graphic, Stockton will be the Ava member city with the largest number of new CARE/FERA households, with its 46,527 customers just edging out Oakland. Stockton also has the highest portion of residential customers receiving energy assistance, at 41%.  In fact, the three San Joaquin County members take the top three spots, with Lathrop second at 30% followed by Tracy at 26%.

CARE and FERA customers also benefit from the bill credits Ava has been able to generate in recent years.  The Ava Board recently agreed to use $22.4 million to fund a one-time bill credit of $100 for the 108,000 customers currently on CARE and FERA.

According to the CPUC’s DG Stats database, Stockton is a leader by a long shot in the deployment of customer-sited solar, among cities in Alameda and San Joaquin counties. With 14,000 installations adding up to over 120 Megawatts (MW) of capacity, the city has almost double that of runner-up Manteca. Over 11% of housing units in Stockton have solar. The Zip code 95212, in northeast Stockton, has over 20% penetration.

While most of the systems are residential, Stockton also leads in commercial customers with solar, with 192 customers hosting almost 30 MW of capacity, far more than Oakland’s runner-up at 87 systems.

Much smaller Lathrop ranks high in solar capacity per household, at 1.39 kW, trailing only zip codes in Tracy and Manteca. Lathrop also leads with the most industrial customers with solar, with four factories hosting 2.3 MW of capacity.

Stockton also leads Ava communities in having the most solar serving low-income households.  

California has offered four main programs to encourage low-income solar. The Single-family Affordable Solar Home (SASH) program was the first such program in the country, running from 2009 to 2019, funding solar on almost 10,000 homes statewide. In the Ava territory, Oakland had the most SASH homes, with 220. Stockton had 90, with 55 installed in 2018 alone.  

The SASH program was replaced by DAC-SASH, which has installed solar on 3,000 homes in disadvantaged communities (DACs) to date. Stockton has a big lead in this program, with 524 homes completed and another 80 in the pipeline. Manteca is in second place with 129 homes solarized so far, followed by Lathrop with 76.

The Multi-Family Affordable Solar Home (MASH) program ran from 2009 to 2021, putting solar on 328 apartment buildings statewide. Oakland led in this category too, with 32 buildings hosting 2.8 MW of solar. Stockton had five buildings, installing 420 kW of capacity. 

MASH was superseded by the Solar on Multifamily Affordable Homes (SOMAH) program in 2019. The program currently has 659 projects statewide, serving almost 50,000 housing units, with $58 million paid out for completed projects. Alameda County has finished only 3, but has 24 in the pipeline, which will serve over 2,000 households when complete. San Joaquin County has 2 done, both in Stockton, and 8 more coming, to serve over 500 households.

Stockton’s two completed projects serve 168 apartments, and six more currently in the works will serve 260 housing units. Oakland has 11 buildings completed or in the works, serving 962 units.

We previously reported on electric vehicle adoption in Ava member communities. We have now updated the EV dashboard here with data through September 2024 (Q3).  

It shows that Alameda County continues to be a national leader on EVs, ranking second among the top counties in the state in 2023, with almost 40% market share for new battery-electric, plug-in hybrid, and fuel cell vehicles. Zip codes in Dublin, Fremont, and Tracy lead the way in EVs per household and per capita, with as high as one in ten households driving battery-electric cars.

San Joaquin County lags behind, although Lathrop is in eighth place among Ava Zip codes for BEVs per household, tied with Berkeley’s best Zip code. Stockton has the most registered vehicles of any Ava city, at 258,542, but 95% of them run on gasoline, diesel, or are flex-fuel (gasoline and ethanol). Stockton is tied for sixth among Ava cities for new EV registrations per household in 2023, at 93 per 1000.