LONDON – Solar energy has become one of the fastest-growing sources of electricity worldwide. By the mid-2020s, global installed photovoltaic capacity had surpassed roughly 2 TW, with hundreds of gigawatts being added each year. But not all solar power is created equal. The technologies that convert sunlight into usable energy fall into three main categories: photovoltaics (PV), solar thermal, and concentrating solar power (CSP). Each serves distinct purposes, operates at different scales, and comes with its own set of advantages and limitations.
Photovoltaics (PV): The Dominant Force
Solar panels are a well-known form of solar technology. They convert sunlight directly into electricity by means of semiconducting material, usually silicon. When light strikes the material, electrons are liberated which results in the generation of current. An inverter changes the produced direct current (DC) into alternating current (AC) and the voltage is ready for use in homes, businesses, and the power grid.
There are various configurations for solar energy systems. One type is the grid-connected systems that rely on the utility grid but don't store energy. They make up more than 90% of the residential photovoltaic installations. The systems that use photovoltaic technology and batteries for self-use are becoming popular due to the decreasing price of batteries. The off-grid systems are implemented in the areas that are not covered by the utility lines. Utility-scale solar farms are one of the major applications of photovoltaic systems.
In PV technology itself progress has been made, particularly by 2026 through TOPCon (Tunnel oxide passivated contact) taking over as the top leading technology competing with heterojunction (HJT) and back-contact (BC). With the next-generation technologies such as perovskite solar cells having efficiencies greater than 26 percent in laboratories and multi-junction tandem cells with more than 33 percent efficiency under one-sun, this is only going to get better.
Solar Thermal: Harnessing Heat
Solar thermal is the process of generating heat through solar energy rather than electricity generated from solar panels. The technology is based on using collectors to catch sunlight and convert it into a heat-transfer fluid typically comprising of a water-glycol mixture, which then cycles through a heat exchanger located inside a tank filled with water.
As of late 2023, total solar thermal capacity reached approximately 560 GWth and provided about 440–450 TWh of heat production each year. While solar thermal covers a smaller share of the total energy generation in the world than PV, the technology is very useful in places where there is constant demand for hot water.
Concentrating Solar Power (CSP): The Utility-Scale Heavyweight
CSP systems are drastically dissimilar to conventional systems. They don't turn sunlight into power; instead, they utilize mirrors and lenses to gather sunlight and focus it on the receiver to produce heat that can power a steam turbine. A key feature of CSP technology is the utilization of thermal energy storage (usually molten salt), which allows for generation of power after the sun sets.
There are four primary CSP configurations, each with distinct technical characteristics:
Parabolic Trough Collectors (PTC) are the most popular CSP technology and make up for around 73% of the CSP market in 2026. These technologies focus sunlight on tubes using curved mirrors shaped as troughs. The maximum operating temperature is around 300-400 °C with thermal oils and even 550 °C with molten salt. In April 2026, China General Nuclear began building a 50 MW parabolic trough plant in Tibet at a height of 4,550 meters (the highest CSP plant ever). The company also confirmed the world's largest (8.6-meter) molten salt parabolic trough collector system in Qinghai.
Solar Power Towers (SPT) or central receiver systems use a collection of heliostats (sun-tracking mirrors) to concentrate sunlight onto a receiver located on a central tower. These systems achieve very high temperatures between 400-750 °C, with other advanced systems reaching temperatures up to 1,000 °C. Concentration ratios can also exceed 1,000. In June 2026, the company CGN started the Golmud 350 MW CSP Demonstration Project in Qinghai which is said to have the world's largest heliostat field area and thermal storage capacity in one single unit. Tower CSP is also advancing at high altitudes, as Amdo Tushuo 100 MW tower CSP plant has combined 100 MW of tower CSP and 8 hours of thermal storage with PV capacity of 900 MW and it was able to complete the first milestone of commissioning solar field in August 2026.
Linear Fresnel Reflectors (LFR) take the form of flat or curved mirrors that direct sunlight towards the receiver unit. LFR technology offers a complete solution for CSP systems that is less complicated, more affordable and efficient. The Chinese renewable energy giant, Three Gorges Corporation, installed a 1 GW hybrid solar energy power generation plant in Hami, Xinjiang. This innovative plant contains a 900 MW photovoltaic and 100 MW linear Fresnel CSP unit with eight hours of molten salt heat storing system. The plant alone covers about 800,000 square meters and will utilize a staggering 260,000 mirrors for sunlight collection.
Parabolic Dish Collectors (PDC) represent point-focus technologies that harness the parabolic shape of a reflector to gather solar rays at the focal point of the dish. The concentration ratios of the PDCs can reach levels of up to 3,000 and they can operate at temperatures over 750 °C. Although they can be very efficient as the dish-Stirling systems have demonstrated 29.4% efficiency results in field tests, their application remains very small.
The Hybrid Future: PV and CSP Working Together
One of the more important trends with regard to 2026 is the merging of photovoltaic (PV) and concentrating solar power (CSP) technologies in hybrid generation plants, including the Hami project in Xinjiang. It is the first innovation of its type in solar power generation as it relies on PV electricity generation by day and CSP technology with storage system during the night and in overcast conditions which will generally make solar power generation much more continuous than before. There are even more ambitious projects being planned such as the one announced by China Energy Engineering Corp that has commenced construction of another hybrid project that will bring together 1.3 GW of PV and 150 MW of CSP.
As solar power grows its reach, and renewable sources are projected to reach about 45% of all electricity worldwide by the year 2030, understanding the specific function of PV technologies, solar thermal, and CSP becomes essential. Each one of the technologies has its use: PV can produce electricity in a decentralized manner or bulks of power cheaply, solar thermal should be used for heating, while CSP with storage technology provides on-demand green energy to enterprises.
