Dive Brief:

An Xcel Energy resource solicitation received more than 400 individual proposals, the utility reported last month, including what may be record-low prices for renewable energy paired with energy storage.

The median price bid for wind-plus-storage projects in Xcel's all-source solicitation was $21/MWh, GTM Research's Shayle Kann noted on Twitter, and the median bid for solar-plus storage was $36/MWh. Previously, the lowest known bid for similar solar resources was $45/MWh in Arizona.

The utility detailed the bid information in its 30-day status report for the solicitation, dated Dec. 28. Bids are beng evaluated and a first round of projects will be selected next month.

​Dive Insight:

Xcel Energy's latest resource solicitation returned renewable energy and storage bids so competitive they have the sector abuzz on social media. While Kann noted details about battery duration and sizing were not made available, the price of battery-paired solar in the solicitation is a full $9/MWh cheaper than the cheapest contract announced just last year.

In the Arizona case, storage added $15/MWh to the PPA price. Here the combo bids are $3-$7/MWh higher than standalone wind and solar. Lots of caveats (online by 2023, don't know the storage duration, etc.), but incredible nonetheless. — Shayle Kann (@shaylekann) January 4, 2018

Last year Xcel subsidiary Public Service Co. of Colorado announced a plan to shutter 660 MW of coal-fired capacity at the Comanche Generating Station and issued a competitive request for proposals of up to 1,000 MW of wind, 700 MW of solar, and 700 MW of natural gas and/or storage.

In its status report, Xcel told state regulators that "the response to this solicitation is unprecedented." The utility received 430 total individual proposals including 238 total projects. More than 350 of the individual proposals are renewable energy proposals or renewable energy with storage proposals, according to the report.

For comparison, Xcel said it received 55 bids in its 2013 all-source solicitation.

Many developers provided multiple bids for a single project resulting in significantly more bids than projects, Xcel noted. Differing bid information, such as different proposed in-service dates, different power purchase

agreements terms, and different ownership structures can result in multiple bids from a single proposed

project.

Of the 238 projects proposed, 99 projects included some level of utility ownership.

Importantly, Kann noted the addition of storage did not appear to raise bid prices as much as in the past. Wind energy with battery storage was bid at $21/MWh, just $3 higher than wind-only. In the Arizona deal last year, the addition of storage added about $15/MWh to the power purchase agreement bid.

Before the Arizona deal, the previous cheapest solar-plus-storage project was $0.11/kWh, set last July for a PPA between the Kauai Island Utility Cooperative and AES Corp. for a project that combined a 28 MW solar array with a 20 MW, 100 MWh battery system.