Input discipline for accurate energy
Voltage and amp‑hour entries convert to energy using kWh = (V × Ah) ÷ 1000, matching DC nameplate ratings. For series strings, voltage rises; for parallel strings, amp‑hours rise. If you already know usable energy from test data, switch to direct kWh to avoid rounding from nominal values. Keep units consistent, and treat efficiency as the system round‑trip value, not the cell coulombic metric, for realistic delivered‑energy results. Include temperature derating too.
Cost stack and yield effects
Total upfront cost is built from cells plus balance‑of‑pack items such as BMS, enclosure, busbars, thermal parts, and assembly labor plus QA. Fixed engineering costs are spread across quantity, so low‑volume builds show higher unit cost. Overhead is applied as a percentage uplift on subtotal, while scrap rate is modeled as a yield loss by dividing by (1 − scrap%). This mirrors how rework and rejects inflate effective spending per good pack.
Landed cost drivers: logistics, duty, and tax
Logistics, duty, and tax often dominate landed cost for imported components. Model freight and insurance as per‑pack logistics, then apply duty to the goods value, because duties typically exclude domestic installation costs. Taxes are commonly assessed on goods plus logistics plus duty, so a small tax rate can compound. Contingency captures volatility in freight, material markets, and schedule risk. Use the currency selector to keep reporting consistent across quotes and invoices accurately.
Lifetime delivered energy and levelized cost
Economic comparison improves when cost is normalized by lifetime energy delivered. Usable energy per cycle equals total kWh × depth‑of‑discharge × efficiency. Lifetime cycles are limited by the smaller of stated cycle life and cycles per year times calendar life years. Multiply usable per cycle by lifetime cycles to obtain delivered kWh, then divide total upfront plus O&M by delivered kWh. The result approximates a levelized cost of stored energy for comparisons.
Using results for engineering decisions
Outputs are most valuable when used for sensitivity checks. Start with cell cost per kWh and scrap rate; these usually produce the largest swings. Next test labor, overhead, and fixed engineering to see how automation or volume affects unit cost. Compare per‑pack and fleet totals to validate impact, then review delivered‑energy metrics to align with warranty targets. Document the assumptions for each scenario so stakeholders can reproduce decisions and audit changes later.