C&I Grew While Residential Peaked and Fell
Commercial and industrial solar added 2,345 MWdc in 2025, a 6% year-over-year gain, at the same time residential solar was heading into the contraction that followed the Section 25D tax credit’s expiration. Every stats page on this site tracking residential volume shows the same story from the other direction: SEIA forecasts residential installations down 18% to 21% for the full year of 2026. C&I is not immune to that broader environment, but 2025’s growth shows the segment was not moving in lockstep with residential demand even before 2026 began.
Why 2026 Dips Before a 2027 to 2030 Rebound
SEIA forecasts a 13% decline for C&I solar in 2026, driven largely by California’s regulatory changes, a state-specific policy shift rather than a national demand collapse. Looking further out, SEIA projects C&I returning to roughly 6% annual growth from 2027 through 2030, as rising retail electricity rates make commercial solar’s economics more compelling and the segment’s growth leans less on the residential Section 25D credit that ended for systems installed on or after January 1, 2026. Residential solar has no equivalent path back to that credit outside of third-party-ownership structures; C&I’s 2026 dip and its projected rebound are shaped by a different set of forces entirely.
The Numbers
Commercial and industrial (C&I) solar grew 6% in 2025, adding 2,345 MWdc.
SEIA forecasts a 13% decline for C&I solar in 2026, driven largely by California’s regulatory changes.
SEIA projects C&I solar returning to roughly 6% annual growth from 2027 through 2030, as retail electricity rates rise and the segment leans less on the now-expired residential federal tax credit.
The Section 25D residential tax credit ended for any system installed on or after January 1, 2026, a driver behind why C&I’s 2026-to-2030 trajectory looks different from residential’s.
For comparison, residential solar installations are forecast down 18% to 21% for the full year of 2026, a contraction C&I is not experiencing on the same 2026 timeline.
Sources
The external data in this article draws on the sources below. Figures described in the text as estimates or industry triangulations are directional and are not attributed to a single dataset.