Off-grid Raspberry Pi Zero solar power sizing

Two combined sources: RaspberryTips “Outdoor Raspberry Pi Setup” (undated) and SwitchDoc Labs “Sizing your Solar Panels for the Raspberry Pi” (August 2021).

RaspberryTips

Pi Zero W power draw: ~120 mA idle, ~150 mA with WiFi active. Worked example for a 192 mA average load: 8 peak sun hours/day → needs 3,072 mAh for 16 nighttime hours → 6,144 mAh minimum after accounting for 50% depth-of-discharge on Li-Ion → recommends a 10,000 mAh battery with an 8.46W panel, explicitly advising over-provisioning (“if calculation says two panels, buy three”). Enclosure guidance: humidity and heat are the top two risks; recommends IP67-rated junction boxes, heat sinks + ventilation in warm climates, and condensation/ventilation planning before deployment. Mentions the GeekPi UPS HAT (four 2S 18650 cells, ~24,000 mAh) as an off-the-shelf battery-management option.

SwitchDoc Labs

Runtime formula: (Solar Hours × Sun% × Panel Current) × Efficiency ÷ Device Current = Hours. Worked example for a Pi Zero W (160 mA average w/ WiFi dongle): four 2W/6V/330mA panels (8W total) + a 6600 mAh LiPo battery survives 24-hr operation, with night-only draw (~3,011 mAh) comfortably under the 6600 mAh capacity. Disabling HDMI output saves ~20 mA — worth doing on a headless logger. Recommends monitoring actual battery voltage (not the regulated 5V rail) for low-battery shutdown, with ~3.5V/cell as the cutoff; suggests an INA3221 for voltage/current monitoring. Charging + boost-converter losses run ~15% (85% system efficiency) — a good de-rating factor for any capacity plan.

Why it matters for this archive

Best available worked sizing methodology for powering a Pi Zero fully off-grid on solar/battery — directly usable for a South Texas outdoor monitoring build. See Small-scale passive-thermal experiment monitoring.