​July in MISO was defined by day-ahead energy spreads diverging between MISO North and MISO South. The day-ahead four-hour top-bottom (TB4) spread at Indiana Hub averaged $619/MW-day, up 93% year over year, reaching a 12-month high. The four southern hubs cleared between $153/MW-day and $198/MW-day.

Modo Energy's virtual BESS benchmarks reflect that split. A BESS in MISO North could have earned $609/MW-day, 83% more than MISO South's $333/MW-day. MISO North's benchmark revenue was 63% day-ahead energy while MISO South revenue was 80% day-ahead regulation. This increase contrasts with the trend from June, when Indiana real-time spreads fell 32% YoY in a comparably calm month.

The month's ancillary service and arbitrage value concentrated into four days that produced 41% of July BESS revenue in MISO North. Two heatwaves drove that concentration: an early-July heat dome behind the July 1 real-time spike, and a mid-month heat wave behind the elevated day-ahead prices.

Key takeaways

• A BESS in MISO North could have earned $18.3/kW-month ($609/MW-day) against MISO South's $10/kW-month ($333/MW-day). The gap was driven by day-ahead arbitrage.
• The Indiana Hub day-ahead TB4 spread rose 93% year over year to $619/MW-day, the highest of the past year.
• Two price events shaped July. Demand peaked at 122 GW on July 1 as Indiana Hub cleared $1,415/MWh in real time in the 7 PM hour, and the mid-month heat wave pushed day-ahead TB4 spreads to $2,642/MW-day on July 15.
• Solar generation rose 49% year over year to a 7.2 GW average, but coal and natural gas together supplied 71% of MISO generation.
• Regulation anchored the MISO ancillary stack: day-ahead regulation held at $18/MWh while spinning and supplemental reserve prices fell by 50% or more year over year.

Northern batteries out-earned Southern batteries by 83% in MISO

Modo Energy's virtual BESS (vBESS) benchmarks simulate the revenue available to a battery energy storage system dispatching against market prices. For this article, the North benchmark is sited at Indiana Hub (LRZ6) and the South benchmark at Arkansas Hub (LRZ8).

In July a BESS at Indiana Hub earned $11.5/kW-month from day-ahead energy alone, six times the $1.9/kW-month at Arkansas Hub. The South's reliance on regulation reflects suppressed southern energy prices: the transfer limit between the regions constrains flows and holds southern spreads down.