+--------------+-----------+-----------------------+
| energy_usage | device_id |  timestamp            |
+--------------+-----------+-----------------------+
| 10           | 1         |  2019-02-12T01:00:00  |
| 16           | 2         |  2019-02-12T01:00:00  |
| 26           | 1         |  2019-03-12T02:00:00  |
| 24           | 2         |  2019-03-12T02:00:00  |
+--------------+-----------+-----------------------+

+--------------+------------------+--------------------+-----------+------------+
| energy_usage | energy_usage_day | energy_usage_night | device_id |    date    |
+--------------+------------------+--------------------+-----------+------------+
| 80           | 30               | 50                 | 1         | 2019-06-02 |
| 130          | 60               | 70                 | 2         | 2019-06-03 |
+--------------+------------------+--------------------+-----------+------------+

WITH temp AS (
  SELECT *, SUM(usage) OVER(win) > 50 qualified,
    SUM(usage) OVER(win) - 50 rolling_sum,
    EXTRACT(HOUR FROM timestamp) BETWEEN 8 AND 19 day_hour,
    EXTRACT(MONTH FROM timestamp) month,
    FORMAT_TIMESTAMP("%Y-%m-%d", timestamp) date
  FROM `project.dataset.table`
  WINDOW win AS (PARTITION BY device_id, TIMESTAMP_TRUNC(timestamp, MONTH) ORDER BY timestamp)
), temp_with_adjustments AS (
  SELECT *,
    IF(
      ROW_NUMBER() OVER(PARTITION BY device_id, MONTH ORDER BY timestamp) = 1,
      rolling_sum,
      usage
    ) AS adjusted_energy_usage
  FROM temp
  WHERE qualified
)
SELECT ROUND(SUM(adjusted_energy_usage), 4) energy_usage,
  ROUND(SUM(IF(day_hour, adjusted_energy_usage, 0)), 4) energy_usage_day,
  ROUND(SUM(IF(NOT day_hour, adjusted_energy_usage, 0)), 4) energy_usage_night,
  device_id,
  date
FROM temp_with_adjustments
GROUP BY device_id, date

+--------------+-----------+-----------------------+
| usage_charge | device_id |  timestamp            |
+--------------+-----------+-----------------------+
| 0.2          | 1         |  2019-02-12T01:00:00  |
| 0.6          | 2         |  2019-02-12T01:00:00  |
| 0.1          | 1         |  2019-03-12T02:00:00  |
| 1.2          | 2         |  2019-03-12T02:00:00  |
+--------------+-----------+-----------------------+

+--------------+------------------+--------------------+--------------+------------------+--------------------+-----------+------------+
| energy_usage | energy_usage_day | energy_usage_night | usage_charge | usage_charge_day | usage_charge_night | device_id |    date    |
+--------------+------------------+--------------------+--------------+------------------+--------------------+-----------+------------+
| 80           | 30               | 50                 | 1.2          | 0.4              | 0.8                | 1         | 2019-06-02 |
| 130          | 60               | 70                 | 2.5          | 1                | 1.5                | 2         | 2019-06-03 |
+--------------+------------------+--------------------+--------------+------------------+--------------------+-----------+------------+