Solar in SPP West: The Next Growth Market for Corporate Procurement

Jan 26, 2026
By
Katie Hoffmaster

For corporate and non-utility energy buyers looking for low-priced solar power purchase agreements (PPAs), Southwest Power Pool's (SPP) expansion into the Western Electricity Coordinating Council's (WECC) territory — with RTO West and Markets+ — is an attractive alternative to the Electric Reliability Council of Texas (ERCOT) market.

Figure 1: Broker Reported Solar PPA Pricing Trends (LBL: Utility-Scale Solar - 2025 Data Update)1

By April of 2026, SPP will expand its footprint into Colorado with RTO West, integrating seven western entities (see dark green region on the SPP map below) into SPP’s wholesale market. Solar (and other) projects interconnecting to these entities will be able to participate in the broader SPP market, making virtual PPAs possible for the FIRST TIME in non-CAISO WECC. PPA rates in these newly expanded areas are competitive with ERCOT pricing, the lowest rates in the U.S.

Figure 2: SPP Market Expansion Map2

Historically, solar PPAs in non-CAISO WECC have been the lowest in the U.S. due to the region’s exceptional solar resources, but they were largely ONLY available to utilities. With SPP’s expansion into WECC, corporate and other non-utility buyers will be able to access lower-cost areas through virtual PPAs – just like in legacy SPP and other wholesale markets (e.g. ERCOT, MISO, and PJM).

Figure 3: 2022-Present Sample PPAs (LBL) Utility-Scale Solar - 2025 Data Update

By 2027, SPP is expected to expand into WECC even more with Markets+, which will encompass the rest of Colorado and Arizona (shown in yellow on the SPP map).

Now is a good time, as there are limited projects that are advanced in the queue and can begin delivering energy ahead of the tax credit cliff to provide the lowest priced PPAs, settling in the expanded market via traditional corporate deals.

Definitions:

1) RTO West refers to the Southwest Power Pool's Regional Transmission Organization expansion, which aims to enhance grid reliability, increase operational efficiency, and promote renewable energy integration. This expansion allows for the integration of the Eastern and Western grids under SPP RTO, creating a unified market that benefits both new and existing members. The RTO West initiative is part of SPP's strategic plan, Aspire 2026, and is expected to provide significant benefits to the Western energy landscape.

2) Markets+ is a program that centralizes day-ahead and real-time unit commitment and dispatch, facilitating the integration of renewable generation. It aims to enhance reliability, increase participant value, and equitably compensate participants. The program is part of SPP and designed to support the growing fleet of renewable generation across the Western U.S.

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1Seel, Joachim, Julie Mulvaney Kemp, Anna Cheyette, Will Gorman, m R Darghouth, Dana Robson, Joseph Rand, and Seongeun Jeong."U.S. Utility-Scale Solar, 2025 Data Update." (2025).

2Southwest Power Pool. Markets+. (2025). https://www.spp.org/western-services/marketsplus/

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