Solar energy surpasses coal for the first time, changing the electricity landscape in the United States

Introduction

In May 2026, the US power industry will reach a historic turning point: solar power generation will surpass coal for the first time and become the third largest source of electricity. According to the latest data analysis from energy think tank Ember, solar power generation accounted for 12.8% of the US electricity supply that month, while coal fell to 12.2%. This structural change not only marks a new stage in the energy transition of the United States, but also reveals the substantial substitution of renewable energy for traditional fossil fuels under multiple drivers of cost, policy, and market. This article is based on publicly available data and objectively analyzes the significance and subsequent challenges of this milestone event from dimensions such as power generation, proportion evolution, seasonal characteristics, and industry drivers.

1、 Data comparison: role reversal of solar energy and coal

Ember data shows that in May 2026, the US solar power generation reached a record high of 45.5 terawatt hours (TWh), a year-on-year increase of 17%, higher than the previous peak set in July 2025. The coal power generation during the same period was 43.4 TWh, a decrease of 11% compared to May 2025. This is not just a one month accidental breakthrough, but also a trend turning point - five years ago in May 2021, the proportion of coal-fired power generation was still 19.7%, while solar energy was only 5.4%; By May 2026, the proportion of solar energy had surpassed coal by 0.6 percentage points. It is worth noting that the coal power generation in April has hit a historic low of 39.3 TWh, and although there was a slight rebound in May, the overall decline is evident. Solar energy maintains a strong growth trend, even though it has not yet entered the traditional peak of power generation in May (usually in June and July), its power generation has already broken records. Ember predicts that solar power generation is expected to break through again in the summer of 2026, further widening the gap with coal. From the perspective of power structure, solar energy has risen to become the third largest source of electricity in the United States, second only to natural gas (about 38%) and nuclear energy (about 19%). Coal ranks fourth. Behind this ranking change is the dual effect of the doubling of solar installed capacity over the past five years and the accelerated retirement of coal-fired power units. According to data from the US Energy Information Administration (EIA), the installed solar capacity in the United States increased from approximately 95 gigawatts (GW) to over 190 GW between 2021 and 2026, while the installed coal capacity decreased from approximately 220 GW to less than 170 GW.

2、 Structural driving factors: cost, policy, and market

The reversal of solar energy over coal is not accidental, but the result of long-term accumulation of multiple factors. 1. The cost competitiveness continues to improve. According to data from the National Renewable Energy Laboratory (NREL) in the United States, the levelized cost of electricity for large ground-based photovoltaic power plants has decreased to approximately $35/megawatt hour by 2025, while the cost of coal-fired power (including environmental compliance) is generally between $45-60/megawatt hour. Although natural gas remains the cheapest power source (around $25-30 per megawatt hour), the fuel free cost characteristics of solar energy give it a significant advantage during peak daytime periods. 2. Policy incentives and mandatory targets. The Inflation Reduction Act (IRA) of 2022 provides a 30% investment tax credit for solar projects for up to 10 years and introduces a production tax credit, greatly reducing the financing threshold for projects. In addition, clean energy standards set by states such as California, New York, and New Jersey, such as the 100% zero carbon electricity target, directly drive utility companies to purchase solar power. 3. Natural gas price fluctuations and coal withdrawal. From 2025 to 2026, natural gas prices will continue to be low (approximately $2.5-3.5 per million British thermal units), which will squeeze coal's share in the base load market for natural gas power generation. But more importantly, coal-fired power plants are accelerating their retirement due to environmental regulations (such as EPA's mercury and air toxic substance standards, wastewater restriction rules) and economic disadvantages. Approximately 12 GW of coal-fired power capacity will be retired in the United States by 2025, and an additional 8 GW is expected to be retired by 2026. 4. Energy storage matching improves scheduling flexibility. The intermittency of solar energy, which is high during the day and absent at night, was once the main obstacle to its increasing proportion. But from 2023 to 2026, the installed capacity of battery energy storage in the United States will grow rapidly. As of May 2026, the operating capacity of large-scale battery energy storage has exceeded 35 GW, which can release about 3-4 hours of electricity after sunset, thereby reducing solar power curtailment and enhancing the ability to replace coal-fired power during nighttime periods.

3、 Seasonal characteristics and future prospects

The solar power generation reaches its peak in June and July each year, mainly influenced by solar altitude angle, sunshine duration, and weather factors. In May 2026, a record of 45.5 TWh was set, and it is expected to further climb to 48-50 TWh in June and July. Ember's forecast is based on the current installed capacity and the capacity factor of the same period last year - assuming that the capacity factor in June remains the same as June 2025 (about 23%), the power generation is expected to exceed 47 TWh. In contrast, coal power generation usually increases slightly in summer due to the increase in air conditioning load, but the data for May 2026 (43.4 TWh) is already lower than solar power and showing a year-on-year downward trend. If solar energy continues to reach new highs in June and July, coal may continue to be suppressed throughout the summer. Looking ahead to the second half of 2026 and beyond, solar energy surpassing coal is expected to evolve from a "single month event" to a "normalized pattern". EIA predicts in the 2026 Energy Outlook that by 2027, solar energy will surpass coal for the first time in terms of annual electricity generation, and by 2030, solar energy will account for 20% while coal will fall below 8%. This judgment is based on the following assumptions: the continued implementation of IRA policies, the rhythmic advancement of coal-fired power retirement plans, and the continued decline in energy storage costs (expected to decrease by another 30% from 2025 to 2028).

4、 The impact on the electricity market and carbon emissions

The structural significance of solar energy surpassing coal is that the carbon emission intensity of the power system will significantly decrease. By 2025, the US power industry will emit approximately 1.6 billion tons of CO2, with coal-fired power plants contributing about 60%. If solar energy gradually replaces coal-fired power generation, the reduction in coal-fired power generation in May 2026 alone (approximately 4.5 TWh of replacement) corresponds to a reduction of approximately 4 million tons of CO2 emissions. Looking at the whole year, if solar power generation increases by 20% year-on-year, it can reduce an additional 30-40 million tons of emissions. However, this transformation also brings new challenges to the electricity market. The large-scale integration of solar energy has led to a "duck shaped" net load curve during the day - the difference between the daytime net load trough (full photovoltaic capacity) and the evening net load peak (photovoltaic decline, increasing demand) widens, requiring more rapid response resources (such as gas turbines or energy storage) to balance. From 2025 to 2026, many states in the United States have experienced the phenomenon of "noon trough electricity prices" (even negative electricity prices), which puts certain pressure on the return on investment of solar energy projects. In the future, long-term energy storage (more than 4 hours), demand response, and cross regional transmission expansion will be the key to supporting further growth of solar energy.

Conclusion

In May 2026, the solar power generation in the United States exceeded that of coal for the first time, which is an inevitable result of cost reduction, policy driven, and stock structure reshaping. This is not only a numerical change in energy statistics, but also means that the fossil fuel dominated electricity era is being replaced by clean energy. Although solar energy still faces challenges in intermittency and grid flexibility, its grid connected consumption capacity during peak summer months has been validated. With the improvement of energy storage facilities and the acceleration of coal-fired power retirement, solar energy is expected to continue to surpass coal in annual power generation after 2027, providing core support for the United States to achieve the goal of reducing emissions by 50% -52% in the power industry by 2030. This milestone event also provides a reference transformation path and quantitative benchmark for other high coal-fired power countries around the world.