California utilities release maps showing where solar generation projects can easily be developed (2024)

California has just taken a major step forward in bringing clean local energy online. The Clean Coalition played a major role in this progress as a leading advocate for streamlining the interconnection of distributed energy resources (DER) to the electric grid.

On December 28, 2018, California’s major utilities, Pacific Gas & Electric (PG&E), Southern California Edison (SCE) and San Diego Gas & Electric (SDG&E), published their updated Interconnection Capacity Analysis (ICA) maps, or ICA 2.0. These online grid maps are a product of the Distribution Resources Plan (DRP) proceeding at the California Public Utilities Commission (CPUC), in which the Clean Coalition has been the leading non-utility intervenor.

The expected July publication of the ICA 2.0 maps was delayed because of unwarranted issues raised about exposing easily discernable grid details, such as the location of substations. This “concern” led the utilities to take the drastic step in September of restricting access to their existing maps, which had already been publicly available since 2012. Fortunately, that action was reversed when Administrative Law Judge Robert Masonruled on October 9 that the previously published maps should be made publicly availableagain.In a subsequent ruling on December 17, 2018, Masondirected the utilities to make the ICA 2.0 maps available by December 28, 2018through a public portal, like the predecessor maps had been accessible for over half a decade.

ICA maps assess all points on the existing distribution grid for accommodating new DER capacity without significant grid upgrades. The maps, which contain details on available interconnection capacity, are crucial tools for bringing DER online more quickly and cost-effectively.

Interconnection is often the most complex, uncertain and time-consuming aspect of DER project development. This is particularly true for smaller projects, which can easily be rendered uneconomic due to a lack of predictability in terms of interconnection costs and timelines. For this reason, since 2010 the Clean Coalition has successfully pushed for utilities to provide increasingly detailed and accurate interconnection data in the grid maps, which help project developers and property owners determine whether sites are appropriate for serious DER siting consideration.

The ICA 2.0 update represents the first full-scale release of ICA maps with reliable data. Although the utilities published demonstration ICA maps in 2015 with detailed data, those maps relied on models and assumptions that did not meet the accuracy standards required by interconnection engineers. In contrast, the ICA 2.0 maps can be used with a high degree of accuracy for interconnection assessments. The new maps evaluate the most common interconnection capacity factors at the node level on every line section of all primary distribution circuits — that is, at every point on the circuits where there can be a change in values that would affect the ICA results. Significantly, for the sake of facilitating certainty and accuracy for project developers and property owners, the maps are publicly available and will be updated every month.

Example of new ICA maps, showing color-coded existing capacity and detailed information for the specific identified point, as well as circuit load profiles, at the Paul Sweet substation.

“The updated ICA maps make a great leap forward from what has been available to date,” said Sahm White, Economics and Policy Analysis Director at the Clean Coalition. “The new maps take a huge amount of risk and uncertainty out of DER project development, which will result in more of these projects being built at lower cost. A developer can now determine, early in the decision-making process, what size of project can be sited at any location with little or no modification to the existing grid. This is critical for easily choosing the best locations for siting projects, and then for projects that are moved forward, being informed with realistic costs and timing expectations regarding interconnection.”

Craig Lewis, Executive Director of the Clean Coalition, added, “ICA 2.0 provides an unprecedented level of transparency and certainty through publicly available grid data. There is still a long way to go to truly streamline interconnection processes for commercial-scale DER in California, but ICA 2.0 provides the first real foundation for distribution grid planning in the United States. With continuing efforts, California will keep improving, and other states, and even FERC, will at least match California’s progress in streamlining interconnection for local renewables and other commercial-scale DER.”

The Clean Coalition has been a major contributor in the effort to publish and improve the ICA maps, providing the vision for modernized, streamlined interconnection processes and leading the effort to realize that vision.

While ICA 2.0 is a welcome major development, there are more improvements to come. Next steps have already been defined for ICA 3.0 and include these additional ICA refinements:

  • Current ICA maps pertain to just the distribution grid. ICA 3.0 will add constraints related to the transmission grid that could affect interconnection — for example, other projects being proposed for that part of the transmission grid.
  • ICA 2.0 maps model each circuit, but they do not show how a circuit may affect neighboring circuits. ICA 3.0 will dynamically model multiple circuits and their impact on one another.
  • ICA 3.0 will aim to update the maps in real-time, to ensure that the results are never out of date.

PG&E’s updated ICA map can be accessedhere. SCE’s map, known as their Distributed Energy Resources Interconnection Map, or DERIM, can be foundhere. SDG&E’s map can be accessed byregistering at this link.

News item from Clean Coalition

California utilities release maps showing where solar generation projects can easily be developed (2024)


What is the potential solar energy in California? ›

California has the technical potential to install 128.9 GW of rooftop solar panels, which would generate 194,000 GWh/year, about 74% of the total electricity used in California in 2013.

What percent of California is solar? ›

2021 Total System Electric Generation
Fuel TypeCalifornia In-State Generation (GWh)Total California Power Mix
Total Renewables67,46133.6%
Total System Energy194,127100.0%
11 more rows

How big is California solar capacity over time? ›

According to Environment California Research & Policy Center's Renewables on the Rise 2023 dashboard, solar in the Golden State has grown tremendously over the last decade. In 2022, California generated nine times as much solar power as it did in 2013, enough to power 5,876,199 typical homes.

What is the solar power record in California? ›

MOST SOLAR ENERGY EVER GENERATED AND SERVED: Solar projects served a new high of 17,170 MW, an increase of over a thousand MW from last year's peak – enough to power millions of homes. And, the amount of demand served by solar hit a new record, powering 86.4% of electricity demand.

What city in California uses the most solar energy? ›

The report designates Los Angeles a “Solar Superstar,” meaning it boasts 100 or more watts of solar PV capacity installed per capita. Los Angeles is home to 649.9 megawatts of solar capacity total, which comes out to 166.7 watts per person. San Diego has the next highest rooftop solar capacity with 468 megawatts.

Will California really pay for solar panels? ›

The California Public Utilities Commission's Self-Generation Incentive Program (SGIP) offers rebates to residents for installing a solar battery along with the solar panel. The rebate amount varies depending on battery storage capacity and the local utility company.

What happens to excess energy from solar panels in California? ›

But now, the state and its grid operator are grappling with a strange reality: There is so much solar on the grid that, on sunny spring days when there's not as much demand, electricity prices go negative. Gigawatts of solar are “curtailed” — essentially, thrown away.

Can you get solar for free in California? ›

On top of the federal ITC, there are incentives exclusively for certain Californians who decide to go solar. In particular, these incentives target low-income households, offering them a way to get free solar installation. This program is called the DAC-SASH rebate program.

How big of a solar farm could power the US? ›

“If you wanted to power the entire United States with solar panels, it would take a fairly small corner of Nevada or Texas or Utah,” he explained. “You only need about 100 miles by 100 miles of solar panels to power the entire United States….

What is the largest solar project in California? ›

The largest combined solar and energy-storage project in the U.S. is now online and operating in California's Mojave Desert. The sprawling megaproject stretches across 4,600 acres in Kern County and is located on private land as well as the Edwards Air Force Base.

Is net metering going away in California? ›

But in 2023, California changed its net metering policy to something called net billing, also known as NEM 3, making solar a much less compelling offer to homeowners. Net metering is one of the most important solar incentives, and the way it works is pretty simple.

What is happening with solar in California? ›

In December 2022, the CPUC slashed the financial credits provided to new solar users for excess solar energy generated from their panels and sent to the grid. Utilities pushed for the change to weaken demand for solar, their biggest competition in California.

What is the potential of the solar energy market? ›

Solar Power Market Size [2022-2029] worth USD 373.84 Billion by 2029 | Exhibiting CAGR of 6.9% The global solar power market size was valued USD 167.83 billion in 2021 and USD 234.86 billion in 2022 respectively.

What is the potential of solar energy in the US? ›

As a result of new solar projects coming on line this year, we forecast that U.S. solar power generation will grow 75% from 163 billion kilowatthours (kWh) in 2023 to 286 billion kWh in 2025. We expect that wind power generation will grow 11% from 430 billion kWh in 2023 to 476 billion kWh in 2025.

Which state has the highest potential for solar energy? ›

Rajasthan has the highest solar power generation potential of any state in the country. The state recently surpassed Karnataka as the leading state in solar installations. As of August 2023 Rajasthan's operational solar power projects produced roughly 17.8 GW of solar energy.

How much energy does a solar panel produce in California? ›

You can calculate your estimated annual solar energy production by multiplying your solar panel's wattage by your production ratio. This means a 400-watt panel in California will produce about 600 kWh in a year, or about 1.6 kWh daily.


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