Space solar index falls 1.87% as solar-cell costs retreat

(SpaceEnergy) The SE Space Solar Supply Chain Cost Index (SESSCI) fell 1.87% in July to 113.29 points as lower semiconductor and solar-cell manufacturing costs outweighed continued strength in advanced materials.

The principal driver was the semiconductor and solar-cell manufacturing component, which dropped 2.47% month on month to 94.972 points. The decline coincided with persistent oversupply and inventory pressure across China’s photovoltaic manufacturing chain.

Taiwan-based market intelligence provider TrendForce’s EnergyTrend, which tracks prices and supply-demand conditions across the photovoltaic industry, said buyers remained cautious, with polysilicon procurement dominated by small-volume purchases and inventory drawdowns.

EnergyTrend estimated polysilicon inventories at around 520,000 tonnes in mid-July and said the supply-demand imbalance was worsening. Solar-cell inventories had risen to around 12 days of supply, while sluggish shipments pushed mainstream cell transaction prices lower.

EnergyTrend said ample raw-material inventories at ingot producers were delaying purchasing demand, adding to near-term pressure on polysilicon prices.

Semiconductor packaging and integration costs also weakened, falling 4.20% to 92.530 points, reinforcing downward pressure on the overall index.

The decline was partly offset by advanced inorganic materials, which edged 0.51% higher to 122.322 points. Aluminium structures remained the most elevated component of the basket at 152.795 points, although the sub-index fell 1.64% from June.

The July decline reversed some of the SESSCI’s gains earlier in 2026. Despite falling from 115.44 points in June, the index remained 6.15% above its December 2025 level of 106.73 points.