BESS IRR and DSCR: Chile, Mexico, and the Report Case
IRR is the annualized return implied by the cash flows. DSCR is cash left after tax divided by debt service. They do not peak on the same battery. That is why the highest return is rarely the case that goes to the committee.
OPTIMUS does not lend and does not publish a Chile or Mexico return benchmark. A live study uses your node, your prices, and your costs. The homepage Chile contract demo is sample math, not your result.
What moves the return
Return rises when more of the battery's energy is sold at a wide gap between the charge hour and the discharge hour, and when the plant is not oversized for that gap. In Chile, tolls, losses, and curtailment come out of a contract before that gap is real. In Mexico, a wholesale node and an on-site CFE bill are two different engines. Do not add them together.
A larger battery can raise energy revenue and still lower the return if the extra capacity is idle in too many hours.
What moves coverage
Coverage is the cash left after tax, divided by the debt payment. The lender sets how much room they want. OPTIMUS does not set that test.
Coverage gets tighter when debt is sized off the highest-return case, when a dry year cuts output, or when merchant revenue is treated as if it were a contract. The size with the highest return often has the least room under that test.
Why the two peaks are different sizes
The return peak asks, "Which size makes the equity case look strongest?" The coverage peak asks, "Which size still pays the debt in a weaker year?" Those questions pick different megawatt-hours.
The Recommended Case is the risk-adjusted size, not the highest return. It is the one case the committee and the lender can use. Battery sizing is where that size is chosen. The lender pack is where coverage is built from the same case.
Sample only, not a project result
This table is an illustration of the conflict. The words "higher" and "lower" are not Chile or Mexico results.
| Case | Return | Room under the lender's coverage test | What you do with it |
|---|---|---|---|
| Highest return | Higher | Tighter | Keep it as a sensitivity. Do not send it as the only case. |
| Recommended Case | Lower | More room | This is the case in the memo and in the model a lender reads. |
A live comparison uses your site. Start from the market you are actually in: Chile or Mexico.
Questions
- Why focus on Chile and Mexico instead of ERCOT?
- OPTIMUS runs Chile, Mexico, and the Argentina tender. This note explains how return and coverage can point at different battery sizes. It does not publish a US market benchmark.
- What coverage do banks require for batteries?
- The lender sets the coverage test. OPTIMUS does not lend. We show the same battery under a sponsor case, a base case, and a downside case so you can see which size still fits that test.