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Solar Generator Sizing Calculator

Size a portable solar generator or power station for a set of loads.

About Solar Generator Sizing Calculator

Portable power stations must satisfy two independent requirements: energy capacity for the day’s consumption and inverter rating for the peak simultaneous load. Either can be the binding constraint. Solar input must be large enough to replace a day’s consumption within available sun hours, or the unit steadily depletes across a trip.

Formula

Solar Generator Sizing

Battery Wh = daily Wh × autonomy ÷ usable fraction; inverter W = peak load × 1.25

usable capacity
Share of nominal capacity the management system permits
peak load
Highest simultaneous draw, which sets the inverter rating

Worked example

With the default values below, Solar Generator Sizing Calculator returns Battery Capacity Required of 1,764.7. Change any input above and every figure here is recalculated in your browser.

Inputs used

Daily energy neededminimum 0 Wh
1,500 Wh
Peak simultaneous loadminimum 1 W
800 W
Days without solaraccepts 0.5–7 days
1 days
Usable capacityaccepts 0–100 %
85 %
Solar panel inputminimum 0 W
400 W

Results

Battery Capacity Required
1,764.7 Wh
Inverter Rating Required
1,000 W
Hours of Sun to Recharge
4.688 h
Runtime at Peak Load
1.875 h
Verdict
Solar input can recharge the unit within a day

Step by step

  1. 1Values used
  2. 2Solar Generator Sizing
  3. 3Battery Capacity Required= 1,764.7 Wh
  4. 4Inverter Rating Required= 1,000 W
  5. 5Hours of Sun to Recharge= 4.688 h
  6. 6Runtime at Peak Load= 1.875 h
  7. 7Verdict= Solar input can recharge the unit within a day

Assumptions and limits

  • The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Solar Generator Sizing calculated?

Battery Wh = daily Wh × autonomy ÷ usable fraction; inverter W = peak load × 1.25 Portable power stations must satisfy two independent requirements: energy capacity for the day’s consumption and inverter rating for the peak simultaneous load. Either can be the binding constraint.

Why does Solar Generator Sizing matter?

Solar input must be large enough to replace a day’s consumption within available sun hours, or the unit steadily depletes across a trip.

What values do I need to enter?

This calculator takes 5 inputs: Daily energy needed, Peak simultaneous load, Days without solar, Usable capacity, Solar panel input. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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