Solar sizing is a system calculation. Sensors, the data logger, modem and camera all consume energy, and a short transmission peak can affect the power design even when the average load is low. Ask for a calculation tied to your actual capture and reporting schedule.
Build a daily energy budget
For each component, estimate power in watts and operating time in hours per day. Add sleep, sensing, communication and capture periods without double-counting overlapping loads. Include conversion losses and realistic retry activity. The result is daily energy in watt-hours. Validate this estimate on a complete device using the intended firmware and network conditions.
Calculate usable battery energy
Nominal battery energy is voltage multiplied by amp-hours. Usable energy is lower after allowed depth of discharge, conversion losses, ageing reserve and temperature derating. Divide usable watt-hours by the measured daily load to estimate no-sun days. State every assumption; battery capacity alone cannot demonstrate autonomy.
An illustrative calculation
For illustration only, a 12 V, 20 Ah battery contains 240 Wh nominal energy. If an assumed 70% is usable, it provides 168 Wh. At a hypothetical 24 Wh daily system load, that is seven days before any additional reserve. This is arithmetic for planning, not a specification or performance claim for a Zhice Yunlian product. A camera or weak cellular signal can change the load substantially.
Allow the solar array to recover
The panel must support normal operation and recharge the battery after poor weather. Use local low-sun-season data, mounting direction, shading, dirt and controller losses. Compare expected daily generation with demand and agree how quickly a depleted reserve should recover. Annual average sunshine is a poor substitute for the limiting season.
Treat cold-weather charging separately
A discharge temperature limit is not the same as a charge temperature limit. Ask for the battery chemistry, cell datasheet, battery-management settings and solar-controller limits. Some lithium batteries require charge inhibition or a heating strategy below their permitted range. Confirm heater consumption in the energy budget and validate all components at the project temperature.
Write an acceptance test
Agree the full configuration, initial charge, ambient conditions, capture schedule and simulated network availability. Measure low-voltage behavior, restart recovery and the effect of failed transmissions. Keep the logs and document any load-reduction modes. Final panel and battery sizes should be confirmed in the project specification and quotation.
Before requesting a quotation
Send a clear project brief.
- Daily sensor, logger, camera and modem operating schedule
- Measured average load and peak current at supply voltage
- Minimum temperature and charge/discharge limits
- Required no-sun days, reserve and recharge target
Continue your project
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Farm station selection checklist ↗
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