Start from the electrical load profile
Battery and panel selection requires the complete system load, not just the nominal rating of one lamp. List signal heads, controller, communication equipment and other loads. Record operating hours and the applicable indication duty cycle.
Estimate stored-energy requirements
Calculate daily energy demand from power and operating time, then account for the planned autonomy and system losses. Select usable battery capacity using the battery manufacturer’s limits, temperature behavior and aging allowance. Nominal capacity alone does not establish usable energy.
Check the solar resource at the site
Use location-specific solar data for the design period and consider shading, orientation, dirt and seasonal conditions. Annual average sunshine is not a substitute for the conditions governing availability. Panel output and charging losses must be considered together.
Match the charging and protection equipment
Check battery chemistry, system voltage, charging profile and the electrical limits of the panel and charge controller. Verify protection, cable sizing and environmental suitability using the equipment documentation and applicable installation requirements.
Validate the proposed configuration
Request a calculation sheet stating load, solar assumptions, autonomy, temperature range and replacement assumptions. Check charging and load behavior during commissioning. A sample panel-and-battery combination should not be presented as suitable for every site.