OREANDA-NEWS. June 23, 2015. In the first quarter of this year, with unseasonably warm dry weather tamping down wind flows in California, the amount of power generated by the state’s 44 wind farms fell off by around 35% compared to the first quarter of 2014, according to data filed with the US Federal Energy Regulatory Commission and the Energy Information Administration compiled by Platts.


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While that was a first, clear signal that wind power had its distinct draw-backs, but two more recent dates — June 8 and 9 — seemed something like days of reckoning for renewables in California.

As demand for power rose and generation surged to meet it, rain, widespread cloud cover and poor wind pushed down the amount of wind and solar generation available to help meet the demand. Because of the shortage of renewables, prices surged.

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With increasing frequency, the variability of wind and solar is being compounded by weather in an electricity market where renewables are destined to play an increasing role in the future.

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According to California Independent System Operator data, total generation on June 8 was, 755,676 MWh, significantly higher than the 631,900 MWh generated on June 1, which was a day with more typical electricity demand.

On June 1, renewable generators produced 159,756 MWh of power, or 25.3% of total generation. Also on that day, wind generators produced just over 62,089 MWh, while solar PV generators produced 50,519 MWh and solar thermal generators produced 5,259 MWh.

On June 8, however, renewable generation took a deep drop to 108,949 MWh, or just 14.4% of the total.

Wind generation fell the furthest, to 13,794 MWh, a 77.8% drop from the more typical June 1 total. At 49,074 MWh, solar PV generation was off 2.8%.  Solar thermal, at 6,428 MWh, was strong.

The impact on prices of the cumulative renewable decline, though, was immediate at the two main electricity hubs in the state. The Cal-ISO average real-time locational marginal price, or LMP, for June 8 was \\$244.20/MWh at NP 15, while it was \\$176.54/MWh at SP15. One week prior, the NP15 average real-time LMP price was \\$27.81/MWh, while the average LMP price at SP15 was \\$24.47/MWh.

On June 9, Cal-ISO’s “sum of generation” reached a still high 721,883 MWh, aided by 182,152 MWh of imported power. The import total was roughly 10% higher than the  average for the week.

The fall-off, though, of renewable generation on June 9 was even more pronounced than on June, declining to just 97,427 MWh, or 13.50% of total generation.

On that day, however, it was solar’s turn to collapse. PV solar generation fell  to just 14,518 MWh, down from 49,074 MWh the day before, a 70% drop. Solar thermal fell off the table, totaling just 1,424 MWh, a 78% drop from the day before. Wind was 41,359 MWh, compared to 13,794 the day before.

Prices, nonetheless, settled down somewhat on Tuesday, June 9. The average NP15 LMP price for that day was \\$50.62/MWh, while the average SP15 price was \\$48.99/MWh.

On June 10 total generation was closer to “normal” at 687,654 MWh, with renewables back up to 152,462 MWh, or 22.17% of the total.  Wind generation on June 10 was 61,999 MWh, solar PV 46,081 MWh and solar thermal 4,928 MWh.