Version 2.3. Updated May 2026. The model is reviewed quarterly. When it changes, all historical scores are recalculated.

May 2026 changes.

1) Hybrid weight formula. After auditing the composite-score weights, we adopted a hybrid formula to address two gaps: (a) the original documented weights (35/30/25/10) under-emphasized permit approval history, and (b) the actual live weights over-emphasized data uncertainty, creating a "state-halo effect" where counties in strong-RPS states appeared safer than their actual approval records warranted. The new formula — 33% Compliance + 23% Saturation + 24% Trajectory + 20% Uncertainty — restores saturation importance and moderates uncertainty to fix both issues. It uses whole numbers for transparency.

2) Permit-record adjustment to Compliance Stringency. We compute each county's approval rate from recorded utility-scale permit decisions and add a penalty if it's below 30%, or a small bonus if it's above 80%. To handle counties with sparse history (1–2 decisions, or none), the observed rate is blended with the state's base rate using Beta-Binomial smoothing — effectively, every county starts from its state's average and moves toward its own observed rate as more decisions accumulate. The output is tagged with a confidence level (high for ≥3 decisions, moderate for 1–2, preliminary for 0); the county page shows a "Preliminary score" badge when the rate is mostly state context rather than local evidence. This moves grades toward actual board behavior, while never falsely treating a quiet county as if it had been silent on solar.

3) Moratorium hard cap. Any county with an active utility-scale solar moratorium is scored at the worst-possible value (100, grade F), regardless of underlying sub-scores. An active moratorium means the site is functionally closed; the underlying numbers don't override that.

4) Two new context badges shown next to the county grade — both separate from the score itself, so a weak county in a strong-policy state still reads as a weak county and a county with significant land constraints is flagged even if its ordinance reads permissively:
• State policy (Favorable / Mixed / Hostile): a read on the state's RPS policy framework.
• Site constraints (Light / Moderate / Heavy): conservation easements, prime farmland, federal-land overlay, FEMA floodplain. Only appears when we have constraint data for that county — counties with no badge are unknown, not unconstrained.