Solar Powered Sensor Sizing Calculator

Work out solar powered sensor sizing instantly with clear inputs, formula shown and shareable results.

About Solar Powered Sensor Sizing Calculator

Solar sensor nodes must be sized on the worst month, not the annual average, because a December deficit cannot be repaid from a June surplus. Panel size is daily energy divided by worst-month sun hours and system efficiency, and the battery must ride out the longest expected cloudy spell.

Formula

Solar node sizing

panel W = daily Wh / worst-month peak sun hours / efficiency; battery Wh = daily x autonomy days / usable fraction

Worked example

With the default values below, Solar Powered Sensor Sizing Calculator returns Panel size required of 1.61. Change any input above and every figure here is recalculated in your browser.

Inputs used

Daily energy consumption: 1.8 Wh
Worst-month peak sun hours: 1.6 h/day
System efficiency: 70 %
Days of autonomy: 7 days

Results

Panel size required: 1.61 W
Battery capacity required: 15.75 Wh
Battery at 3.7 V: 4,257 mAh
Generation on a design day: 1.80 Wh

Step by step

1Values used
2Solar node sizing
3Panel size required= 1.61 W
4Battery capacity required= 15.75 Wh
5Battery at 3.7 V= 4,257 mAh
6Generation on a design day= 1.80 Wh

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 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

Why size on the worst month?

Because the battery only buffers days, not months. A node sized on the annual average dies every winter.

How many days of autonomy?

5-10 days for temperate latitudes, more where extended overcast is common. Each extra day is cheap in battery terms compared with a bigger panel.