Self-Reliant Living Home

OFF-GRID Array Sizing Worksheet

Use this worksheet to figure the total number of solar modules required for your system. To find average sun-hours per day in your area (line 3), check local weather data, look at the map below or find a city on the next page that has similar weather to your location. If you want year- round autonomy, use the lowest of the two figures. If you only want 100% autonomy in summer, use the higher figure. The peak amperage of the module you will be using can be found in the module specifications. You can also get close enough if you divide the module's wattage by the peak power point voltage, usually 17 to 18.5.



	1 . Total average amp-hours per day from the System Loads Worksheet, line 10.

	2 . Multiply line 1 by 1.2 to compensate for loss from battery charge/discharge.

	3 . Average sun-hours per day in your area.

	4 . Divide line 2 by line 3. This is the total solar array amps required .

	5 . Optimum or peak amps of solar module used. See module specifications.�

	6 . Total number of solar modules in parallel required. Divide line 4 by 5.

	7 . Round off to the next highest whole number.

	8 . Number of modules in each series string to provide DC battery voltage:

		Number of Modules
	DC Battery Voltage	in Each Series String
	12	1
	24	2
	48	4

	9 . Total number of solar modules required. Multiply line 7 by line 8.



	THESE CHARTS SHOW THE SUN-HOURS PER DAY FOR THE U.S.