Know your data sources.

ONS (Operador Nacional do Sistema Elétrico) — Brazil's national electricity grid operator. Public Tempo Real REST/JSON feed, no credentials. Real-time national system load (SIN, ~77 GW), generation mix by source (hydro, thermal, wind, solar, nuclear), marginal operating cost (CMO) by submarket (Southeast/Center-West, South, North, Northeast) in R$/MWh, the energy balance snapshot (generation, load, import/export and interchange by submarket plus international ties with Argentina/Paraguay/Uruguay), and reservoir energy storage (EAR). Joins the power-markets family (ercot/spp/nyiso/caiso/aemo/cammesa/eirgrid).

CAMMESA is Argentina's wholesale electricity market and grid operator (SADI). This connector exposes real-time, public demand and temperature for the 24 provinces and 8 regions plus the system-wide total, refreshed every 5 minutes (today, yesterday, same-day-last-week, and the dispatch forecast), and the live generation mix by fuel (hydro, thermal, nuclear, renewable, imports). No setup needed.

CENACE (Centro Nacional de Control de Energía) — Mexico's grid operator / ISO. The canonical Mexican wholesale-power PML feed (Precios Marginales Locales / Locational Marginal Prices). Public PÚBLICA web service, no key. Hourly LMP per node for day-ahead (MDA) and real-time (MTR) markets, with energy/loss/congestion components. Systems: SIN (national grid), BCA (Baja California), BCS (Baja California Sur). upstream quirks: non-standard port 8082; hard 7-day date-range cap per request (getNodePriceSeries chunks longer histories); node keys are system-specific (a SIN key under BCA returns ZERO_RESULTS); no node-catalog endpoint; Spanish field names; price strings parsed to numbers.

EirGrid Smart Grid Dashboard — the all-island Irish transmission system operator (Republic of Ireland + Northern Ireland). Public REST/JSON, no credentials. Live 15-minute system demand (MW), wind and solar generation actuals and forecasts (MW), the live fuel mix (gas/coal/renewable/net-import shares), named interconnector flows (EWIC, Moyle, Greenlink), carbon intensity and emissions, and System Non-Synchronous Penetration (SNSP). Region can be all-island, Republic of Ireland (ROI), or Northern Ireland (NI). Joins the power-markets family (caiso/ercot/aemo/entsoe/cammesa).