RINA and Hawthorne Map 300 MW Solar-Plus-Storage Plan for Washington Data Demand

A Solar-Plus-Storage Project Takes Shape in Grant County, Washington

Grant County, Washington, has become a pressure point for a new kind of electricity demand. Utilities in the region are receiving requests from digital-infrastructure customers that exceed the load they currently serve, and developers are being asked to deliver power that is not only large-scale but also reliable and financeable. The Appledale Energy Center is one response: a planned 300 megawatt solar photovoltaic project paired with a 300 megawatt, four-hour battery energy storage system.

The developer, Hawthorne Renewable Energy, hired global engineering consultant RINA to carry out early-stage technical work on the site. RINA optimized the physical layout using county slope limits, easements, setbacks and environmental constraints, and settled on a preliminary design with roughly 400 MWp of direct-current capacity. The firm also produced a preliminary project layout, completed a bankable energy yield assessment for the final preliminary design, evaluated adjacent parcels, reviewed geotechnical plans, and inspected transformer manufacturing.

The project is targeting full operation by 2028 and is expected to produce more than 650 gigawatt-hours per year, which the companies equate to powering more than 50,000 Washington households. The storage component matters because it allows solar output to be dispatched when large-load customers such as data centers actually need it, rather than only when the sun is shining.

What RINA's Early Engineering Work Reveals About the Appledale Development

Why storage is central to the Appledale pitch

Solar alone produces energy on a solar curve; data center customers need firm, schedulable power. Pairing 300 MW of solar with a 300 MW, four-hour battery turns a variable resource into a dispatchable one and increases the value of the project to large-load customers. That is the core logic behind Appledale, and it is why the battery is not a peripheral add-on but a central part of the site plan, with reserved areas for the BESS and a project substation near the point of interconnection.

What RINA's scope actually de-risks for Hawthorne

RINA's work concentrated on the uncertainties that can stall or reprice a development before construction begins. The design-optimization phase addressed Grant County's average-slope limit, easements and setbacks, translating them into a fenced development envelope. A bankable energy yield study with P75 and P90 exceedance values gives Hawthorne a performance range that lenders and investors can evaluate. The geotechnical review and transformer inspections then move the project beyond paper design and toward procurement decisions by identifying specification gaps, fabrication quality issues and commercial risks early.

The regional demand picture makes Grant County more than a local story

The backdrop is digital load growth. The account states that utilities in the region are facing requests much larger than their current peak load. For a site with existing transmission access and favorable conditions, that creates urgency, but it also raises the bar: developers must show how a project will meet grid requirements and customer expectations. The additional-parcel evaluation at Appledale signals that Hawthorne is exploring whether more capacity can be added around the existing boundary, which would make the project more flexible for an expanding data center load.

Practical Lessons for Developers, Investors and Data-Center Buyers

For renewable developers, investors and data center buyers tracking this project, the Appledale case offers several specific takeaways.

• Use early layout optimization to protect capacity. RINA moved from a constrained site envelope to an estimated 400 MWp DC design by incorporating Grant County's average-slope limit, easements and setbacks before locking the fence line.
• Treat the 4-hour battery as core project infrastructure. The site plan reserves dedicated BESS space and places a substation near the interconnection point, which is essential for selling dispatchable power to data-center customers.
• Demand bankable P50, P75 and P90 yield outputs before financing. The Appledale study provides annual energy yield plus P75 and P90 exceedance values, giving lenders a defined uncertainty range rather than a single forecast.
• Review adjacent parcels before finalizing scope. RINA's additional-parcel evaluation estimates incremental DC capacity around the existing boundary, allowing Hawthorne to judge whether expanding the footprint improves the project's value.
• Run supplier due diligence early. The transformer inspection program flagged technical gaps, specification deviations and commercial considerations before procurement, reducing schedule and cost surprises ahead of the 2028 target.