IoTTools

Solar Sizing Calculator

Size solar panels and batteries for remote IoT devices based on power consumption, autonomy, and solar availability.


Inputs

Typical values: 3–6 h/day depending on location.

Accounts for panel degradation, wiring losses, and weather margins. Typical: 1.2–1.5.


Formula Explanation

The average power consumption of the device is calculated as:

Pavg = V × Iavg

The daily energy requirement is then:

Edaily = Pavg× 24 h

The battery capacity needed to maintain operation during cloudy days:

Cbattery (Wh) = Edaily× Autonomy (days)

The recommended solar panel size, considering a safety factor for real-world conditions:

Ppanel (W) = (Edaily/ PSH) × SF

Where PSH is the Peak Sun Hours and SF is the Safety Factor.


Reference: Panel Size by Current and Autonomy

Assuming 3.3 V system, 4 PSH, 1.3 safety factor.

Current3 days7 days14 daysPanel
50 mA12 Wh28 Wh55 Wh1.3 W
100 mA24 Wh55 Wh111 Wh2.6 W
200 mA48 Wh111 Wh222 Wh5.1 W
500 mA119 Wh277 Wh554 Wh12.9 W

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