Battery storage plays an absolutely critical role in all off-grid solar power and lighting systems. In essence, all the energy produced by the solar array is stored in deep cycle gel batteries, which in turn provides on-demand power to the light fixture or device (ex. security camera, wi-fi, meter etc.)
One of the most common mistakes that many companies in the industry make is designing a system with insufficient battery storage (i.e. anything less than 4x’s the daily load requirement) which will invariably wreak havoc on a system in two ways.
First and foremost, the system will fail under bad weather patterns (not a matter of IF the bad weather patterns occur, but WHEN!) simply because cloudy weather significantly reduces the solar array’s energy production capacity. With less energy stored in the batteries each day, combined with a constant load amount, it’s only a matter of time before insufficient back-up battery power storage is depleted, thus causing the system to fail.
Bad weather patterns notwithstanding, a system designed with insufficient battery storage will also experience a much higher ‘depth of discharge’ which simply means that the batteries will forced to work much harder because the daily load requirement uses a much higher percentage of the battery’s useable capacity each day. A high depth of discharge significantly reduces the overall life expectancy of the batteries to the point where instead of changing the batteries every 5 to 7 years, the system owner will be forced to change the batteries every 2 to 4 years.
At SEPCO, every solar lighting system we design has a minimum of 5 times daily load requirement with 7 to 10 times (or even more) daily load requirement in geographic areas with very low solar insolation like Northeast and Northwest US. This ensures not only ultra-reliable year round system performance, but also provides a robust, cost effective 5 to 7 year battery life expectancy.