MISO Policy Updates

MISO is an emerging market for batteries. As the ISO works through how they are going to account for the unique attributes of storage in their policies, many rules and regulations will be evolving. We’ve got you covered. Our team of policy and operations experts will bring you the highlights – what you need to know and the impact it will have. 

[1] Transmission charges (Tx) for energy storage resources (ESRs) charging from the grid will likely be eliminated later this year.

Background

MISO is the only ISO/RTO that charges batteries for grid charging. It is an artifact of an overly generalized rule intended to charge load for pulling energy from the grid. The Independent Market Monitor (IMM) has been advocating to eliminate the Tx for ESRs given the assets actually help with reliability. In late July, MISO agreed with the position – for the most part. By the end of 2026 they will be removing Tx for economically dispatched ESRs. Self-scheduled charging will still be required to pay the fees.

Impact for Storage

This move will likely make MISO more attractive for storage – both relative to other ISOs and from a purely economic standpoint. Without Tx charges, the cost side of the profitability equation has gone down, which means that overall project profitability should increase accordingly. 

With this update, optimization models will need to be adjusted. At a high level, this changes the calculation of when it makes sense to charge, or opportunities to achieve a target spread.

For economic dispatch, this will require removing Tx as an input to the charging cost calculation. With one less cost weighing down every dispatch hour, the price threshold for charging drops. For any operator that self-schedules, this makes the tradeoff between bidding to get economically dispatched vs self-scheduling more lopsided than it used to be. Self-scheduling still buys you certainty over exactly when you charge. But that certainty now comes at a real cost, since self-scheduled charging is the only path still paying Tx.

Last updated: 08/26/26

[2] MISO is moving to model the Interconnection Service Limit (ISL) as a hard constraint in its clearing engine, ending the need for co-located resources to self-limit their bids.

Background

Today, co-located resources behind a shared point of interconnection (POI) have to self-limit their combined bids to stay under the ISL. Take a 50 MW energy storage resource (ESR) paired with 100 MW of solar behind a 125 MW ISL. In any given interval, the combined bid can’t exceed 125 MW, so the two resources have to coordinate, and neither one can bid its full capacity at the same time.

MISO filed with FERC in March, then revised the filing in June, to change this. Instead of resources self-limiting, MISO will model the ISL directly as a hard constraint in the clearing engine. In practice, this will look similar to CAISO’s Aggregate Capability Constraint (ACC).

Impact for Storage

Once this takes effect, both resources behind the shared POI can bid their full capacity, if desired, and MISO will choose what to clear based on economic merit. Using the example above, the battery would be able to bid its full 50MW and the PV its full 100MW at any given time.

Generally speaking, these changes make it simpler for co-located resources to participate in MISO’s wholesale market, which will likely drive more to the grid.

Last updated: 08/26/26

[3] The clearing process for regulation – MISO’s most lucrative Ancillary Service product – may be changing.

Background

With more solar on the grid, MISO doubled the amount of regulation reserves that they procure at any given time from ~400MW to ~800MW. When this change initially kicked in during the summer of 2024, though, non-performance – largely driven by gas and coal plants – increased in parallel. 

MISO is considering two potential fixes to address the issue:

1. Designing better incentives for regulation performance 
2. Implementing a 24-hour disqualification for any resources that fail to deliver on regulation obligations

Impact for Storage

No matter which improvement the ISO goes with, it is good news for ESRs. Batteries are well poised to deliver regulation given their fast response time and near zero marginal cost to produce power. 

Improving the incentives for regulation will just mean more revenue on the table for storage operators. The 24-hour disqualification may dissuade coal and gas plants that do not plan to deliver from participating, which can increase prices and lead to more regulations awards for batteries. Of course, storage needs to be operated strategically, managing state of charge (SOC), for example, around any obligations to be able to benefit from these changes.

Last updated: 08/26/26