Solar & battery
Solar Battery Quantity Calculator
How many battery modules a target capacity needs, and what the stack costs.
Result
Modules come in fixed sizes, so the installed capacity almost always overshoots the target. Check the manufacturer's limit on how many can be stacked on one system, and whether the inverter supports the full stack; both are common constraints that do not appear in the arithmetic.
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About this calculator
Should I oversize the battery?
Only to the next whole module. Batteries are the most expensive part per kWh and an oversized bank that never cycles fully is capital sitting idle.
Can I add modules later?
Sometimes, and it depends on the system. Some manufacturers require matching age and firmware, and mixing a new module with a three-year-old stack is often not supported.
The formula
modules = (target usable / usable share) / capacity per module, rounded up
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