Flat Savings Tables Hide Battery Degradation in BESS Loan Files

A battery savings table isn't lying; it's just frozen. Most BESS proposals show the same savings number for all ten years. Batteries don't work like that, and a ten-year table that never moves is the easiest place for a credit file to go wrong.

Usable capacity fades every year, and augmentation, when it's needed, costs money the proposal usually doesn't show. If the loan is sized on Year 1 savings repeated for the full tenor, EMI cover in later years may be thinner than the credit note says. By Year 7, actual savings can be well below what was assumed.

The gap between the file and reality

Ingro's illustration indexes savings to Year 1 = 100 and compares two lines over ten years:

• Savings shown in the proposal: flat at 100 every year.
• Actual battery savings: declining with an illustrative ~2.6% per year compounding capacity fade.

At Year 7, where the loan tenor ends in the example, the gap is about 15 points of assumed savings. The fade rate is illustrative; lenders should ask the EPC for the project-specific degradation curve.

The quick stress test

Before signing off on a solar + storage loan, credit teams can ask for three things:

1. Year 1, Year 5 and Year 7 savings, not just Year 1.
2. The year and cost of any planned augmentation.
3. Whether the cashflow uses Year 7 savings, or Year 1 savings repeated for the full tenor.

If the file can't show it, the savings case has not been stress-tested.

Stress-test the savings, not just the sizing

This is Ingro's reading of typical battery degradation behaviour, shared to help credit teams ask sharper questions. It is not a substitute for the EPC's project-specific generation and savings data, which is exactly what lenders should request before underwriting battery storage.