Ethan BrooksBy Ethan Brooks

Updated November 2026

Solar thermal power plants in the world operate mainly in sunny, dry regions with strong direct sunlight, and the largest concentration is in Spain, followed by the United States, China, Morocco, and India. Most use concentrating solar power (CSP), where mirrors focus sunlight to heat a fluid that drives a steam turbine. Installed capacity has grown unevenly, with bursts of construction tied to government incentives and then slowdowns when those incentives ended.

Where Solar Thermal Power Plants Are Located

Spain was the early leader. Plants in Andalusia and Extremadura came online after the country introduced feed-in tariffs in the mid-2000s, and many of them use parabolic trough collectors with thermal storage tanks that let them generate for several hours after sunset. The Solar Thermal Power Plant Spain: How the Plants Work and Where They Stand article covers those sites in more detail.

Shopping for one? See our guide: 7 Best Solar Thermal Energy Power Plant Books for Engineers and Students.

In the United States, the Mojave Desert in California and Nevada hosts the largest cluster of plants, including the Ivanpah facility, which uses power towers rather than troughs. Morocco’s Noor Ouarzazate complex is among the biggest CSP installations anywhere, and it combines trough and tower technology on one site.

China and India have added capacity more recently. India’s Rajasthan region has sites suited to the high solar irradiance found there, and Solar Thermal Power Plant in Rajasthan: How It Works and Why It Matters explains the local context. South Africa, Chile, and the United Arab Emirates have also built or permitted projects, with Chile’s Cerro Dominador plant pairing a tower with molten salt storage.

Factors That Decide Where Plants Get Built

Direct normal irradiance is the single most important factor. CSP only uses the direct beam of sunlight, so cloudy or humid regions perform poorly compared with desert climates. Land cost, water availability for cooling, grid access, and the presence of a stable power purchase agreement all matter as well. A plant without a long-term buyer for its electricity rarely gets financed.

Technology choice also varies by region. Parabolic troughs are the most mature design and dominate the installed base. Power towers offer higher operating temperatures and easier storage integration, and they are increasingly favored for new projects. Linear Fresnel and dish systems make up a smaller share.

What to Watch If You Are Tracking the Sector

  1. Check installed capacity figures from the International Renewable Energy Agency or national energy ministries, since project statuses change quickly.
  2. Distinguish between operating, under construction, and announced plants. Many announced projects never reach completion.
  3. Look at storage hours, not just megawatts. A plant with six hours of storage delivers power differently than one with none.
  4. Read the feed-in tariff or auction terms in each country, because they largely determine whether new plants are built.

FAQ

Which country has the most solar thermal power plants?

Spain has historically had the largest installed CSP capacity, though the United States and China have grown significantly. Rankings shift as projects are commissioned, so check current data before relying on a specific order.

Why are most solar thermal plants in deserts?

CSP needs strong direct sunlight, and deserts offer clear skies and high irradiance. Humid or cloudy areas receive too much scattered light for concentrators to work efficiently.

Can solar thermal plants operate at night?

Plants with thermal energy storage, usually molten salt tanks, can keep generating for several hours after sunset. Plants without storage stop when the sun goes down. Consult a qualified energy engineer or the plant operator for project-specific performance details.

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Ethan Brooks

About Ethan Brooks

Ethan Brooks is part of our editorial team and reviews and edits our solar water heaters guides, checking product details against manufacturer specifications and owner feedback.