-- Set :meter, :from and :to from Grafana variables.
-- Current power:
SELECT timestamp AS "time", active_power_total_kw AS "value"
FROM power_meter_readings WHERE meter = '${meter}' AND $__timeFilter(timestamp);

-- Energy today / rolling 24h (counter increments are reset-safe).
SELECT COALESCE(sum(energy_delta_kwh), 0) AS kwh
FROM power_meter_readings
WHERE meter = '${meter}' AND timestamp >= now() - interval '24 hours';

-- Frequency and outages in selected period.
SELECT min(grid_frequency_hz) AS frequency_min_hz, max(grid_frequency_hz) AS frequency_max_hz,
       COALESCE(sum(outage_delta), 0) AS outages
FROM power_meter_readings WHERE meter = '${meter}' AND $__timeFilter(timestamp);