Houston — The California Independent System Operator maintained its position as the grid with the most renewables across eight US power regions during for the first half of 2019, even as overall renewable output across the country slipped 1% year on year, despite multiple regions setting records.

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Cal-ISO renewable generation averaged 250,248 MWh/d, down 3% year on year, according to ISO data. The majority came from hydro, which dropped 18% year on year to average 89,437 MWh/d. In contrast, solar output increased 5.4% to average 77,384 MWh/d, the largest in the country. Wind output added 11% to average 48,328 MWh/d and set a record of 5,309 MW May 8. The ISO set a renewable penetration record of 78% April 20. Cal-ISO currently has more than 425 MW of solar and 225 MW of wind under construction.

Ranking second in total renewable output was the Southwest Power Pool with 228,216 MWh/d, according to SPP data. Wind averaged 195,158 MWh/d, down 1% year on year, with hydro at 33,057 MWh/d, up 4% year on year. SPP set a wind output record of 16,524 MW on May 17 and a wind penetration record of 67.3% on April 27, as total renewable penetration reached a record of 71.4% on April 27, according to SPP data.

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Electric Reliability Council of Texas renewable generation averaged 222,676 MWh/d, up 1% year on year, according to ERCOT data. Wind output averaged 208,132 MWh/d, down 1.3% year on year, still the largest in the nation, setting a wind output record of 19,672 MW January 21. Solar output jumped 24.1% year on year to average 10,681 MWh/d, and set a solar penetration record of 4.77% April 14. ERCOT expects to add as much as 5,850 MW of wind generation this year and 1,325 MW solar.

The Bonneville Power Administration had the largest percentage of renewables at nearly 83%, even as total renewable output dropped 27% year on year to average 219,911 MWh/d, according to BPA data. Hydro generation decreased 25% to average 204,423 MWh/d and wind fell 49% to average 15,488 MWh/d.

Midcontinent ISO renewable output increased 3% year on year to average 180,002 MWh/d and hydro rose 23% to average 30,490 MWh/d, but wind was flat, averaging 149,511 MWh/d.

PJM Interconnection renewables increased nearly 11% year on year to average 149,998 MWh/d. Wind generation rose 13% to average 75,211 MWh/d, while hydro increased 12% to average 53,608 MWh/d and solar rose 43% to average 6,470 MWh/d.

Renewable output for New York ISO and ISO New England increased 3% and 10% year on year, respectively. NYISO hydro output increased 2% to average 82,404 MWh/d, while wind output jumped 14% to average 13,866 MWh/d. In the ISO New England, hydro output increased 13% to average 29,694 MWh/d, as wind rose 4% to average 10,468 MWh/d.

RENEWABLES OUTPUT AVERAGE PER DAY JAN-JUN 2019 (GWh/change on year) BPA YOY CAISO YOY ERCOT YOY SPP YOY MISO YOY PJM YOY NYISO YOY ISONE YOY Hydro 204.4 -25% 89.4 -18% 3.9 149% 33.1 4% 30.5 23% 53.6 12% 82.4 2% 29.7 13% Wind 15.5 -49% 48.3 11% 208.1 -1% 195.2 -1% 149.5 -1% 75.2 13% 13.9 14% 10.5 4% Solar 77.4 5% 10.7 24% 6.5 43% 4.1 24% Other 35.1 71% 14.7 -11% 5.8 -6% 8.2 0%

(This story originally appeared August 14 and included incorrect historical data on renewables generation for PJM Interconnection. The story has been updated with the corrected information. PJM Interconnection renewables increased nearly 11% year on year to average 149,998 MWh/d. Wind generation rose 13% to average 75,211 MWh/d.)

-- Kassia Micek, kassia.micek@spglobal.com

-- Edited by Pankti Mehta, newsdesk@spglobal.com