# Filter 11: Solar GHI

**Status:** Not started.

**Data key:** `meanDailyGlobalHorizontalRadiationKwhM2Day`. Calculation:
[filter-calculations.md](../filter-calculations.md) §11.

## Findings

**9. The GHI formula assumes hourly, 365-day input.** It is correct for the
current 60-minute, `leap_day=false` requests. If the request interval changes,
the energy sum needs an interval-hours multiplier; leap-day handling would
also need to change the divisor.

**19. The data-sources doc recommends a GHI raster the pipeline does not use.**
Source 4 in `scripts/county_data_sources.md` says county means should come
from a gridded annual GHI raster passed with `--solar-ghi-raster`. The app
values come from NSRDB polygon archive summaries, with representative points
as fallback, applied by `apply_locally_extreme_metric_to_climate_data.py`.

**20. The base build labels any solar CSV as representative-point.** In
`build_county_climate_data.py`, the `--solar-ghi-csv` help text calls it a
representative-point fallback, and the per-row `source` tag is always
`solar-ghi-representative-point`, but the documented build command passes
`data/nrel/county_polygon_ghi_summary.csv`. The apply step later replaces both
the value and the tag, so only the base build's output is mislabeled.

Cross-filter findings that affect this filter, in
[00-cross-filter.md](00-cross-filter.md): 11 (inconsistent aggregation),
16 (the app's NSRDB source link no longer resolves), and 26 (finalized by the
extreme-temperature apply step).

## Decisions

None yet.

## Tasks

Not started; follow the per-filter review checklist in
[pipeline-plan.md](../pipeline-plan.md) §5.