Engineering
Solar PV panel array & battery bank (Ah) sizing calculator with ROUNDUP
Build an illustrative daily-energy panel-count and nominal battery-capacity worksheet with explicit loss assumptions. This is not a complete electrical design.
Account for real-world derate losses and usable Depth of Discharge (DoD)
The panel-count estimate divides daily energy by peak-sun-hours, an assumed delivered-energy factor and panel nameplate watts. The 0.80 factor is an example, not a universal loss figure or a PVWatts default. Use location, season, shading, orientation and system-specific losses; avoid counting the same loss twice.
The battery expression divides required usable energy by nominal voltage and usable depth of discharge. Here A2 is energy demanded at the battery output; conversion/discharge losses and reserve margins are not modeled. If A2 is an AC load, account for those losses before using it. Nominal voltage*Ah is an approximation, and manufacturer capacity, discharge power, aging and temperature constraints also matter.
| Solar / Storage Sizing Step (12,000 Wh/day) | Formula | Design Requirement |
|---|---|---|
| Required DC Solar Array (W) | 12,000 / (5 PSH * 0.80 Derate) | 3,000 W (3.0 kW DC) |
| 400W Solar Panel Count | ROUNDUP(3,000 / 400, 0) | 8 Panels (3,200 W installed) |
| 48V Battery Bank Capacity (Ah) | ROUNDUP((12,000 * 2) / (48 * 0.80), 0) | 625 Ah (30.0 kWh nominal) |
Number of solar panels required (rounded up to whole panels)
A2=DailyLoad_Wh (12000), B2=PeakSunHours (5), C2=DerateFactor (0.80), D2=PanelWatts (400).
=IF(OR(COUNT(A2:D2)<>4,A2<0,B2<=0,B2>24,C2<=0,C2>1,D2<=0),"Invalid inputs",ROUNDUP(A2 / (B2 * C2 * D2), 0))Battery bank capacity in Amp-Hours (Ah) for N days of autonomy
E2=AutonomyDays (2), F2=SystemVolts (48), G2=UsableDoD (0.80).
This is an energy estimate only; inverter power, surge loads, protective devices, wiring, series/parallel limits and local electrical requirements remain separate design work.
=IF(OR(NOT(ISNUMBER(A2)),COUNT(E2:G2)<>3,A2<0,E2<0,F2<=0,G2<=0,G2>1),"Invalid inputs",ROUNDUP((A2 * E2) / (F2 * G2), 0))Try the example
Use the original values or change them to test your understanding.