Free tool
Solar & Battery Sizing Calculator
Size a solar system from your daily energy use: panel wattage, battery bank capacity, inverter rating and the days of autonomy you want to cover.
Three numbers decide a solar system
The array is sized by daily energy, not by peak load. Divide what you use in a day by the peak sun hours and the system losses, and that gives the kilowatts of panel you need. Peak sun hours are not daylight hours: they are the equivalent hours at full rated output, which in Lebanon averages around five and a half across the year but drops closer to four in winter.
The battery is sized by how long you want to run without sun. Lithium gives you around ninety percent of its rated capacity and lasts thousands of cycles. Lead acid gives you half before you start destroying it, so a lead acid bank has to be roughly twice the size for the same usable energy, which usually erases its price advantage within a few years.
The inverter is sized by peak load, the largest amount you would ever draw at one moment. It is a separate question from the other two, and sizing it from daily energy instead of peak demand is the most common mistake in a self specified system.