On 59 consecutive days this year, California's power grid ran entirely on wind, water, and solar energy—a milestone that reveals a harder truth than most people expect about the state's electricity future. While California's retail electricity rates often draw criticism, the wholesale prices that power the grid itself have become the lowest in the entire United States, according to Mark Z. Jacobson, a Stanford University professor of civil and environmental engineering who directs Stanford's Atmosphere/Energy Program.
The numbers tell a story of renewable energy's quiet revolution. Wind, water, and solar power met or exceeded 100% of the California ISO grid's demand for an average of 4.9 hours every single day so far this year. More remarkably, in 125 out of 149 days tracked—84% of the time—renewable sources powered the entire grid at some point during the day. This abundance of cheap, clean electricity is fundamentally reshaping California's energy landscape, even as the state faces other cost pressures that affect what consumers ultimately pay at home.
Jacobson shared his findings on social media in late May, highlighting that the California ISO (Independent System Operator) has maintained both the lowest wholesale electricity prices across the nation and the most stable grid, with no blackouts since 2020. For a state that produces enormous amounts of solar power and benefits from consistent wind resources and hydroelectric capacity, these cheap wholesale prices flow directly from physics: wind, water, and solar all provide free fuel. When fuel costs nothing, electricity wholesale prices drop accordingly.
This achievement carries significant implications for grid reliability and cost stability. A grid powered increasingly by renewables doesn't have to mean fragility or blackouts—the California experience demonstrates the opposite. The state's diversified renewable portfolio, combining solar generation (which peaks during sunny afternoons), wind resources (which often blow strongest at night and during winter), and hydroelectric storage, creates a system with natural built-in balance. As sunnier months approach, Jacobson expects these renewable generation percentages to climb even further.
What makes this moment particularly significant is that it dismantles a common narrative about renewable energy: the notion that clean power requires either a backup of expensive fossil fuels or inherent unreliability. California's grid data shows that a high-renewables system can simultaneously deliver cheap wholesale electricity and consistent supply. The wholesale price advantage ripples through the broader economy, though consumers don't see the full benefit at the retail level due to transmission costs, distribution, and regulatory factors that sit between wholesale markets and home electricity bills.
The findings also underscore why California's aggressive renewable expansion matters beyond state borders. As other regions watch California's grid operate reliably on renewable energy while maintaining cost advantages, the political and economic case for similar transitions elsewhere grows stronger. The data suggests that the future grid isn't a question of whether renewable-powered systems can work—it's simply a matter of building them.
For anyone tempted to dismiss California as a cautionary tale of expensive energy, the wholesale electricity numbers offer a corrective. Yes, retail rates remain high for reasons ranging from infrastructure investment to regulatory choices. But the fuel itself—the wind, water, and sun that power the grid—has become the cheapest source of electricity in the nation, and that advantage only grows as renewable capacity expands.