Path-Q Solar
How should battery degradation affect my estimate of long-term savings?
Answer
Model usable capacity and throughput as declining over time rather than assuming the battery performs like new throughout ownership. Lower capacity can reduce the energy shifted, backup duration, and annual savings, although the effect depends on operating limits, warranty terms, cycling, temperature, and whether the system can still meet your load needs.
Key points
- Use the manufacturer's stated degradation or retained-capacity assumptions only if they apply to the exact model and operating conditions.
- Include round-trip efficiency losses and any reserve that cannot normally be used.
- Consider whether reduced capacity triggers replacement, augmentation, or a change in backup expectations.
What it depends on
- Exact battery model and warranty
- Annual cycles and throughput
- Operating temperature and control settings
- Usable capacity and reserve limits
- Tariff, load, and solar conditions over time
Risks and trade-offs
- A warranty may guarantee capacity only under specified conditions and may offer limited remedies.
- Aggressive cycling can increase savings now while accelerating capacity loss.
- A degraded battery may remain useful for bill shifting but no longer meet whole-home backup goals.
Information you may need
- Warranty capacity and throughput terms
- Expected annual cycles and operating profile
- Usable capacity at installation and end of warranty
- Long-term savings model with replacement scenarios
Your next step
What to do next
Recalculate the financial model using year-by-year usable capacity and a conservative end-of-life assumption, then compare it with the battery warranty.
Path-Q
Find the right next step
Answer a few questions and we’ll narrow your options.
Loading…
SQ00510