El Niño Shifts Solar Irradiance Worldwide

Global solar resource will be reshaped by a strengthening El Ñiño through 2026

The developing El Ñiño, now well above the 0.8 °C threshold on the Niño 3.4 index, is projected to intensify and peak later this year, altering cloud cover and rainfall patterns that directly affect solar irradiance. Historical strong events show regional swings of up to ±10 % in July‑September, and the current event is expected to follow the same pattern.

India will see up to +15 % more sunshine, boosting solar output

Across past strong El Ñiño years, most of India recorded solar irradiance about +10 % higher than average, with Rajasthan – a hub for mega‑solar farms – reaching roughly +15 % above normal. This translates into a proportional increase in energy yield for existing panels, meaning a 1 MW plant could see a comparable boost in output.

Eastern Australia, equatorial Africa and Central America gain modestly

These regions typically enjoy around +5 % more irradiance during strong El Ñiño events. In eastern Australia, places like Toowoomba sometimes exceed the historical range, while other years hover near average, reflecting the interplay of Indian Ocean dynamics.

Western and southern South America, plus East Asia lose about ‑10 % solar resource

The opposite effect hits western and southern South America, where cloudier conditions cut irradiance by roughly ‑10 % during strong El Ñiño phases. Eastern China, including Shanghai, also experiences increased rainfall and a comparable dip in solar resource.

Solcast’s high‑resolution AI model underpins the forecast

Solcast, a DNV company, derives its figures by tracking clouds and aerosols at 1‑2 km resolution using satellite data and proprietary AI/ML algorithms. The platform delivers irradiance estimates with a typical bias of less than 2 % and powers the forecasts used by over 350 companies managing more than 300 GW of solar assets worldwide.

What it means for Israel’s rooftop solar owners

For an Israeli homeowner with a typical 5 kW rooftop system, a +10 % irradiance boost (similar to the average gain seen in Indian‑like conditions) would increase annual generation by roughly 10 % of the typical yield (around 1,700–2,200 kWh per kWₚ). At the residential feed‑in tariff of ₪0.48 /kWh, this would add extra revenue, while a ‑10 % dip would reduce it proportionally. While Israel’s climate isn’t directly tied to the Pacific El Ñiño, the example illustrates how modest irradiance swings can affect household savings.

Outlook and actions for investors and developers

The expected continuation of El Ñiño through 2026 suggests that solar projects in the identified “winner” regions should anticipate higher capacity factors and may benefit from accelerated cash‑flow forecasts. Conversely, developers in the “loser” zones should factor in potential yield reductions when modelling returns. Monitoring Solcast’s real‑time forecasts can help operators adjust maintenance schedules and market trading strategies to capture the most sunshine‑rich periods.

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Key take‑aways

• El Ñiño will likely stay strong until 2026, reshaping global solar irradiance.
• India (especially Rajasthan) could see up to +15 % more solar resource.
• Western/Southern South America and East Asia may lose about ‑10 %.
• Israeli rooftop owners would see a proportional increase in output and revenue from a +10 % irradiance boost.
• Solcast’s AI‑driven, 1‑2 km resolution model powers the forecast used by hundreds of solar firms worldwide.