​SPP West began operating on April 1st 2026, marking SPP’s expansion into the Western Interconnection.

In its first month, Real-Time Top-Bottom four-hour (TB4) price spreads at the new price hub averaged $632/MWh - nearly three times higher than the existing North and South hubs.

​This article is the first in a series of monthly SPP benchmarks tracking wholesale market dynamics across SPP.

Read the article to learn why Real-Time price volatility in RTO West was so high in April, and what battery investors can take away from it.

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Real-Time prices at the SPP West hub hit both negative and positive extremes

​The increased spreads in the West came about as the result of both deeper negative prices and extreme positive prices.

This can be measured by the top-bottom four-hour (TB4) spread, which tracks arbitrage revenues for four-hour duration batteries performing a single cycle a day, the most common configuration in SPP.

Four-hour charge-side prices averaged -$32/MWh at the Western hub, much lower than -$18/MWh of the Wind-driven South.