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Time to look at installing solar power alongside California's highways

California should take advantage of the vast, untapped solar energy potential next to its highways. New analysis of three counties identifies enough solar potential to power over 270,000 homes annually.

By Steven King

California has long been a leader in renewable energy and particularly in solar power.

In 2021, the state ranked number one in the nation for solar energy generation. From a successful Million Solar Roofs initiative leading to more than 1.7 million solar roofs and counting, to a bold 100 percent clean energy commitment by 2045, California has continually been at the forefront of deploying renewable energy solutions.

The state has also seen a 1,020 percent increase in battery storage capacity since 2020, which allows for the storage and use of solar energy once the sun sets each day. However, according to the California Energy Commission (CEC), the state still needs to triple the amount of solar power capacity it builds if we are to meet that crucial 100 percent clean energy target.

Solar power and battery storage are key clean energy tools that can help California transition away from dirty fossil fuels that pollute our air and disrupt our climate. Solar panels allow us to generate clean, renewable energy from the sun’s abundant rays. To quickly and sustainably achieve a future powered by 100 percent renewable energy, California must take advantage of untapped solar energy opportunities. 

Based on new analysis conducted by The Ray, a Georgia-based non-profit that supports state departments of transportation on solar project execution through solar suitability analyses and advising agencies on procurement and deployment processes, three counties examined in Southern California have enormous solar potential within the state-owned right-of-way (ROW).

Together, the counties of Los Angeles, Ventura and San Diego have more than 4,800 acres of suitable space to develop solar power alongside highways, which if covered by solar panels could generate enough electricity to power over 270,000 homes annually. Installing solar panels in these roadside locations could add up to 960 MW of much-needed clean energy capacity and generate an estimated 1,960.9 GWh of electricity per year.

The total acreage available for solar power in these three counties represents the total technical potential if all suitable land was developed, and includes all land alongside highways not located in a zone excluded for safety, environmental, or other reasons. Areas excluded from the analysis include environmentally sensitive or protected lands, areas within roadway clear zones, and areas in close proximity to pipelines, transmission lines, and other infrastructure.

Using prime areas identified by the tool’s suitability analysis—like the San Diego interchange where the Cabrillo Freeway and Clairemont Mesa Blvd. intersect—we can visualize what putting solar panels alongside California’s highways would look like. Just this site alone could produce enough solar energy to power 180 homes for a year. Now imagine the huge clean energy potential if we scaled this approach throughout the entire state of California.

Siting solar panels alongside highways brings a variety of benefits to local communities, the state, and Californians at large:

  • Increase speed and reduce conflict: One of the strongest benefits is that the state already controls all this idle land in its highway rights-of-way, which reduces conflicts and makes it easier to lease or otherwise develop sites for solar energy generation. Because these areas are controlled by the state and are often near existing transmission lines, panels can be built quickly along highways in comparison to large, utility-scale solar projects, which can take six years to complete and 13 years just to plan and construct necessary transmission lines that connect the power to the electric grid. Building solar infrastructure along highways—in already developed or disturbed areas—also avoids many of the land use and conservation concerns that come with siting large amounts of clean energy infrastructure in environmentally sensitive areas like California’s deserts.
  • Contribute to a clean energy future: Putting solar along highways can also contribute significantly to achieving a future powered by clean energy in California. Los Angeles, Ventura, and San Diego Counties have impressive solar power potential that, if fully realized, could generate significant clean, renewable energy that promotes cleaner air and fights climate pollution caused by burning fossil fuels for energy. Installing this solar along highways throughout the state can boost energy reliability, especially when extreme heat waves strain the electric grid, and expand the benefits of clean energy to all Californians. When paired with battery storage systems, these installations can continue providing clean energy to the electric grid even after the sun sets.
  • Save money and generate revenue: Solar along highways presents an opportunity for California to generate revenue from lease payments and electricity generation while potentially saving money by reducing ongoing roadside maintenance expenses. Solar developers can take on the responsibility of maintaining their sites along highways, which can reduce maintenance costs for the state.
  • Leverage the full productivity of existing highways: The Federal Highway Administration issued guidance in 2021 encouraging utilization of state rights-of-way for renewable energy generation. The agency notes that these projects help leverage the full productivity of existing highways, reduce pollution and greenhouse gases, promote energy security and diversity, foster green jobs, create a potential state revenue source and reduce ongoing maintenance expenses. Additionally, the Biden Administration considers repurposing transportation rights-of-way for energy infrastructure like solar and transmission to be a “net-zero game changer” that can help the country meet its climate goals.

A 2020 research report commissioned by Caltrans provides guidance for installing solar generation facilities in its right-of-way and analyzes best practices, which can help California take advantage of solar opportunities alongside highways.

There are examples of solar installations alongside highways in other states, with case studies in Oregon, Georgia and Maine.

This new analysis of Los Angeles, Ventura, and San Diego Counties suggests that California is primed to take a monumental step towards sustainability by going solar along its highway system. Leveraging these untapped areas in Los Angeles, Ventura, and San Diego can generate significant amounts of clean energy, not to mention the potential solar generation of California’s other 55 counties.

To help counter the risk of blackouts and boost local energy reliability, these solar installations can also include battery storage capacity.

California can utilize The Ray’s solar analysis pre-planning tool to analyze solar suitability next to highways and quickly make plans to develop solar in these prime locations. Let’s drive towards a future powered by clean energy in California by putting solar panels alongside our highways. 

Steven King is a Clean Energy Advocate with Environment California Research & Policy Center. Steven leads Environment California’s campaigns to increase clean, renewable energy throughout the Golden State, spearheading efforts to transition away from fossil fuels and address climate change.

This Guest Column was originally published on the website of the Environment California Research & Policy Center: 

 Q1 2024