Are you sure your BESS signals are accurate?

Can you trust what your BESS tells you?

When managing a BESS (Battery Energy Storage System), telemetry signals like SOC (State of Charge) and HSL (High Sustainable Limit) are your eyes and ears on the ground. They tell traders how much energy is available, and how quickly it can be delivered. They tell the grid operator how to dispatch assets and settle market activity.

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Many asset managers operate assuming these signals are reliable. Unfortunately, they’re usually not.

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After reviewing data from several hundred MWh of deployed BESS, we’ve found a troubling pattern: over 15% signal error is common, resulting in millions of dollars of lost revenue for typical grid-scale projects. If you’ve been facing reliability and/or availability issues, the hard truth may be that your BESS is lying to you.

Wholesale markets increase the stakes

Asset managers are encountering more problems with signal error in recent years as operators shift from ancillary services towards more aggressive participation in day-ahead and real-time energy markets. Unlike in ancillary services, maximizing performance in wholesale markets depends on utilizing the full depth-of-discharge of the asset, especially when marginal prices spike and accounting for every last drop of energy matters.

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The consequences are straightforward but painful:

• Underestimates of available energy and power leave potential revenue on the table.
• Overestimates result in penalties and liquidated damages when assets fail to deliver on commitments.
• Conservative market strategies, asset oversizing, and “SOC padding”, where operators add safety margins of 10% SOC or more at top- and bottom-of-charge, sacrifice revenue opportunities.
• Operational efficiency suffers from suboptimal dispatch decisions due to flawed inputs.

Why signal errors persist

We’ve found that flaws in the low-level systems that monitor individual battery cells produce errors that accumulate and compound as they propagate through the various layers of BESS controls, ultimately producing highly inaccurate site-level signals. But why would such flaws exist to begin with? 

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• First, accuracy is not a priority for OEMs who compete mainly on cost and warranty terms.
• Second, third-party plant controls accept inaccurate BMS signals at face-value, even when the error is obvious.
• Third, battery modeling is hard: batteries are extremely complex, non-linear, time-varying electrochemical devices that require sophisticated modeling and algorithms to produce accurate estimates of internal state.

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This results in contemporary BESS architectures suffering from an “integrator approach”, where no single entity takes responsibility for site-level signal accuracy, especially in projects where many disparate vendors are involved.

Zitara’s “cell-to-site” approach to signal accuracy

Zitara takes a different approach. Our software applies advanced battery modeling and algorithms directly to cell-level data gathered from your existing SCADA network, integrating seamlessly with existing control systems. We construct reliable energy and power signals bottom-up from precise cell-to-site models that account for each and every level of the BESS project.

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Our solution works with popular EMS platforms, deploying in an autonomous, on-prem package that eliminates the latency, resiliency, and cyber security issues associated with cloud-based products. In both retrofits and new projects alike, Zitara enhances signal accuracy as well as enabling smart balancing strategies that optimize asset performance and revenue.

Take control of your BESS performance

Don't let signal error limit the potential of your BESS asset. Ask yourself:

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• How confident are you in your energy and power estimates?
• Have you experienced unexpected performance limitations?
• Are you maximizing the financial returns from your asset?

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The solution starts with better data. Reach out today and get a free Insights Report to see how honest your BESS has been with you.