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How 5-minute solar data improved Wärtsilä's forecast capabilities

Navigating the changing weather

Finland's Wärtsilä Oyj Abp, is dedicated to a sustainable future and leverages its 189-year legacy and 15+ years of success with Wärtsilä Energy Storage Inc.'s GEMS Digital Energy Platform to offer solutions that modernizes assets reliably and flexibily without compromising safety or quality. Focused on grid management, WESI provides innovative storage solutions with purpose-built capabilities, catering to utilities, IPPs and other energy customers, delivering technology with purpose-built end-to-end grid management capabilities.

Wärtsilä's GEMS Digital Energy Platform (GEMS) optimizes and controls various generation assets, addressing challenges in managing increased renewable penetration. Using sophisticated controls informed by precise weather forecasts, WESI's GEMS unlocks the value of storage combined with renewables, maximizing the benefits of grid-connected and islanded projects, especially in the emerging trend of solar+storage.

Day-ahead renewables forecasting

Day-ahead renewables forecasting is valuable in deregulated energy markets and increasingly in bilateral contracts, independent of storage. GEMS includes an off-the-shelf capability for solar+storage plants that are contracted under PPAs which mandate the submission of day-ahead hourly energy declarations each morning, with various configurable parameters for the optimization including penalty structures for ramp rate violations (resulting in firm fixed power) or day-ahead hourly energy declarations being met within some tolerance (e.g. +/- 10%). Smaller commitments are easier to achieve, but these reduce energy revenues. Maximizing revenue requires balancing energy delivery with accuracy.

The power of accurate 5-minute solar data in tracking weather patterns

In grid-connected and islanded scenarios, GEMS orchestrates renewable and hybrid systems to reliably generate clean power, reducing the need for traditional thermal generation. GEMS Model Predictive Control, creates forecasted operational plans, incorporating data from Solcast [1], a DNV company, ground-level measurements, and equipment availability. True to Model Predictive Control principles, GEMS continuously recalibrates through perpetual re-optimization using the latest Solcast data. Enhanced by Solcast's weather forecasting, GEMS improves the dispatchability of solar+storage plants, making clean energy more competitive. It determines optimal control strategies in an integrated, automated solution, adjusting to evolving solar conditions. Integrating Solcast API into GEMS, WESI gains high-resolution forecasts, essential for the Renewables+ solution, leading to improved plant performance and cost savings for customers.


  • Accurate and reliable forecasts enable WESI to focus on making control decisions.
  • Continuously updated, high-resolution forecasts improve the performance of renewables and storage plants.
  • Confidence intervals in Solcast’s data underpin the stochastic optimization to incorporate uncertainty in WESI’s GEMS controls.

20231127 Wärtsilä Energy Storage dashboard 770x493pWärtsilä Energy Storage dashboard

Wärtsilä Energy Storage Inc.’s GEMS Digital Energy Platform is an intelligent software control suite that provides forecasts to optimize the fulfillment of customer commitments, including solar+storage PPAs.

We are impressed with how Solcast's five-minute solar data improved our ability to deliver value to our customers by providing accurate high-resolution forecasts. With hourly forecasts, there is uncertainty during sunrises and sunsets that is eliminated with a five-minute forecast. Our projects require precise forecasts and we have been pleased with the correlation to our on-site measurements.

  • Stephen Schneider ,
  • Principal Software Engineer ,
  • Wärtsilä Energy Storage, Inc.

25,000+ Solcast API calls/day


Solcast API calls/day

7+ GWH Global storage fleet

7+ GWH

Global storage fleet

> 95% Revenue capture

> 95%

Revenue capture

Re-optimization every
10 seconds [2]

Re-optimization every

10 seconds [2]


[1] Solcast, a DNV company is a leading provider of solar irradiance data and forecasting technology, dedicated to bringing accurate data to the market and helping enable the energy industry to deliver the resilient power grids it will take to build a solar-powered future.

[2] For a ~250 MW solar+storage plant, this is approximately 1,000,000 new setpoints per day across all inverters to minimize curtailment, balance SOC, and optimally allocate power based on capability.