Recovered settlement variances and sharper BESS arbitrage

The challenge

Altus Energy Trading runs a portfolio that includes a fleet of battery storage assets and an active position in the day-ahead and real-time markets. Settlement statements from the ISO arrived as dense files of charge codes, and the team had no practical way to validate them. Disputes and true-ups were chased reactively, if at all.

• Reconciling ISO charge codes against internal expectations was a manual, error-prone effort that rarely got finished.
• Settlement variances slipped through because no one could shadow the statement line by line before the true-up window closed.
• Battery dispatch decisions were made on rules of thumb rather than a clear view of the DART spread and round-trip efficiency.
• There was no consistent way to evaluate FTR positions against realized congestion.

The team wanted to independently recompute what the ISO owed them and to dispatch their batteries against a defensible economic signal.

The build

Using DOTA, the analytics team built a Shadow Settlement and BESS Dispatch App that parses ISO settlement files, recomputes expected charges by code, and flags variances against the official statement so disputes can be filed before the true-up deadline.

On the dispatch side, the app optimizes battery charge and discharge against the day-ahead and real-time LMP, accounts for round-trip efficiency, and surfaces the DART spread so the desk can capture arbitrage when it is genuinely profitable. FTR positions are evaluated against realized congestion in the same view.

In the first quarter the shadow settlement caught variances we never would have disputed otherwise, and the dispatch logic stopped us from cycling the batteries on thin spreads.

The outcome

Independent shadow settlement surfaced roughly 2.4 million dollars in recoverable variances across true-up cycles that would otherwise have gone unchallenged. Optimizing dispatch against the DART spread and round-trip efficiency lifted realized battery arbitrage margin by about 18 percent.

Altus built the entire app on DOTA in about four weeks, with no traditional software project and no engineering team to staff.