How to Design a Solar-Powered Embedded System for 24/7 Operation

A practical example of designing a continuously powered embedded system using a solar panel, battery, and SUNMOD03PU, including power sizing, system connections, and configuration.

10/9/2026

SUNMOD03PU powering an embedded system with a 50 W solar panel and battery

Many embedded systems installed outdoors need to operate continuously even when no grid power is available. Examples include wireless access points, surveillance systems, monitoring equipment, digital signage, and other remotely installed electronics.

A typical system combines a solar panel, rechargeable battery, charge controller, and the embedded load. The solar panel must provide enough energy during the available sunlight period to both operate the system and restore the energy taken from the battery during the rest of the day.

In this example, we design a system for a continuous 10 W load operating 24 hours per day, using a 50 W solar panel, 12 V / 18 Ah SLA battery, and SUNMOD03PU. We assume approximately 5 hours of effective peak sunlight per day and generally favorable solar conditions. The system can tolerate temporary downtime during extended cloudy periods, so this example is not intended for mission-critical applications requiring guaranteed uninterrupted operation.

System Design

The proposed system uses the following components and operating assumptions:

Solar panel: 50 W, approximately 17 V maximum operating voltage and 2.8 A maximum current
Battery: 12 V / 18 Ah SLA
Load: Continuous 10 W embedded system
Daily charging time: Approximately 5 effective peak-sun-hours
Battery reserve: No additional reserve days assumed

Energy Requirement

A continuous 10 W load consumes:

10 W × 24 h = 240 Wh per day

The battery supplies the system whenever the solar panel cannot provide sufficient energy, including during nighttime operation.

A 50 W solar panel receiving approximately 5 effective peak-sun-hours theoretically produces:

50 W × 5 h = 250 Wh per day

These figures provide a useful starting point, but actual solar energy production will vary with irradiance, panel orientation, temperature, weather, and system losses. Therefore, panel sizing should always include appropriate margin for the intended installation and required availability.

Note that the configuration is illustrative and that a larger panel or reduced load consumption would generally be necessary for a sustainable 24/7 system.

Battery and Charging

A typical 50 W solar panel can provide approximately 2.8 A under favorable conditions. With sufficient sunlight, SUNMOD03PU can charge the selected 12 V / 18 Ah SLA battery while managing power delivery to the embedded load.

System Connection

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The information in this article is provided for general engineering guidance. Please review our Disclaimer before applying these recommendations to your design.

SUNMOD03PU is installed between the solar panel, battery, and embedded system. The solar panel connects to the panel input, the battery connects to BAT+, and the embedded system is powered through the protected L+ load output.

The module can be configured before installation. Alternatively, if the embedded system provides a UART interface, it can be connected to SUNMOD03PU for in-system configuration and access to additional module functions.

The S3 load-shutdown input can also be used by the embedded system to power-cycle itself. If this function is implemented, the system must be designed so that S3 is released after reset, allowing SUNMOD03PU to restore power to the load. Depending on the operating state, reconnection may take up to approximately 60 seconds.

Configuring SUNMOD03PU

For this application, SUNMOD03PU can normally operate in Automatic Mode, allowing the module to manage charging and load operation independently. UART communication is optional unless the host system needs configuration, diagnostics, or additional control.

The important battery settings should be selected according to the specifications of the actual SLA battery being used. In the application-note example, the suggested starting values include a 14.7 V maximum battery voltage, 13.8 V full-battery voltage, 10.0 V empty-battery voltage, and 3 s battery rest time. Final charging thresholds should always be verified against the battery manufacturer’s specifications. See table below:

Design Considerations

This example represents a relatively simple solar-powered embedded system operating in generally favorable conditions. Real installations should account for seasonal sunlight variation, consecutive cloudy days, conversion losses, battery aging, temperature, load variation, and the required system availability.

If uninterrupted operation or operation under harsh environmental conditions is required, additional energy margin, battery reserve capacity, and appropriate protection and system-level design considerations should be included.