How to size an off-grid solar system in BCS

Sizing an off-grid system means designing for the worst case, not the average. You design around your daily energy use in kWh, the loads that must always run, and how many "days of autonomy" you want the batteries to carry you through cloudy stretches — so your property never runs out of power even when the sun doesn't cooperate.

Start with your daily loads (kWh/day)

List your appliances, the hours they run, and especially the heavy loads — water pumps, AC, and refrigeration. Off-grid, you pay to generate and store every kWh, so efficiency matters even more than on a grid-tied system. That daily consumption figure is the foundation of the whole design.

Days of autonomy and the battery bank

"Days of autonomy" is how many days your system can run on batteries alone, with no sun. BCS is very sunny, so fewer days are usually needed, but sites with critical or heavy loads are sized with more reserve. There's a balance between growing the battery bank and adding a backup generator — we set it based on how critical your power is.

Size the array for the lowest month

Generation is designed for the lowest-sun period (winter) so you stay charged year-round. Slightly oversizing the array beats running short in the low months — that way the system covers your consumption even when days are shorter and cloudier.