Global Solar Capacity Reaches 2 Terawatts, Doubling in Just Two Years After Initial 68-Year Climb

Ramez Naam, a prominent clean energy thought leader, recently highlighted the monumental achievement of global solar power, stating, "The first terawatt of solar was the hardest." This observation underscores the accelerating pace of solar energy deployment, as the world's installed photovoltaic (PV) capacity recently surpassed the 2-terawatt (TW) mark, a mere two years after reaching the initial 1 TW milestone. This rapid expansion signifies a dramatic shift in renewable energy adoption, driven by technological advancements and significant cost reductions.

The journey to the first terawatt of solar capacity was indeed a protracted one, taking 68 years from the invention of the first practical solar cell in 1954 until it was achieved in early 2022. This initial phase was characterized by high costs and nascent technology, as detailed by experts like Naam, who has extensively written on the "learning curve" phenomenon in solar. This principle, akin to Wright's Law, posits that the cost of technology decreases exponentially with each doubling of cumulative production, making the initial deployments more challenging.

The subsequent growth vividly illustrates this learning effect. According to estimates from the Global Solar Council and SolarPower Europe, the world's installed solar PV capacity doubled from 1 TW to 2 TW in an unprecedented two-year period, reaching this new benchmark in late 2024. This acceleration is further evidenced by the nearly 600 gigawatts (GW) of solar power installed globally in 2024 alone, marking a substantial increase in annual deployment rates.

Looking ahead, industry projections indicate continued rapid expansion. Analysts forecast that annual global solar installations could reach 1 TW per year by 2030, with total installed capacity expected to exceed 7 TW by the same year. While this growth trajectory is promising for global decarbonization efforts, stakeholders emphasize the need to address persistent challenges, including enhancing grid flexibility, streamlining permitting processes, and crucially, unlocking significant financing, particularly for emerging and developing markets, to sustain this momentum.