Off-Grid Solar System Calculator

Calculate the size of your off grid home power system

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STEP 3: Size Your System for Off Grid

How big should your Off-Grid system be?
If you are moving from a utility-connected home in the 'burbs to an off-grid home in the boonies, you will have the opportunity (perhaps necessity) of downsizing your electricity usage. In order to calculate how large your home power system needs to be, run the calculator below TWICE. Compare and adjust your plans according to your budget and lifestyle.

Run it first with numbers from your current electricity usage.
Then run it with figures from working through the Load Evaluation Worksheet, based on the energy efficient lighting and energy efficient appliances you will choose for your new off-grid home.

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The Cost of Off Grid Solar System: Relevant Topics

Four Easy Steps to Design Your Own System

	Lower Your Energy Use!
	Decide What Kind of System You Need
	Size Your System for Off Grid or Size your System for Grid-tie
	Pick your Components or Let us Design Your System. Call us: 1(800) 472-1142

Off-Grid Energy System Size Calculator
1. How much electricity do you use each month? Look at your electric bills from the past 6 months (or less) and find the average number of Kilowatt Hours (KwH) per month. Put this number in the space to the right. OR Use the Actual Watt Hours per day at the end of your Load Evaluation Worksheet... multiplied by 30 (for monthly total) and divided by 1000 (to convert to KwHours).	KwH/Month
2. What percentage of your house/business power do you want to generate with solar power? If you want to produce 100% of your electricity, put 100.	%
3. How many Peak Sun Hours do you get per day? Look at the Solar Map below to find this number.	Hours

Minimum System Size:	Watts

Divide the Minimum System Size watts by the wattage of the solar panel you are looking at. For example, it would take 24 Mitsubishi 125-watt solar panels to produce 3000 watts..... 3000 divided by 130 = 23+ solar panels.

NOTE: These figures are approximate and do not take into account the variable efficiency ratings of solar panels and off grid inverters. Please work with experienced Wholesale Solar staff to design a system which fits within your budget and can be expanded as needed.

SUN HOURS/DAY ZONE MAP

How Many Sun Hours a Day Do You Get?

Zone 1      6    hours
Zone 2      5.5 hours
Zone 3      5    hours
Zone 4      4.5 hours
Zone 5      4.2 hours
Zone 6      3.5 hours

The hourly figure indicates the average (over the course of the year) amount of insolation (full sun hours) for these zones. These figures are based on the yearly average; consequently, systems based on these figures will provide more power in summer and less in winter. Winter figures for daily solar gain may be from 25% to 50% LESS than these average figures.

Small DC Offgrid Cabin
Medium DC Offgrid Cabin
Medium AC Offgrid Cabin

Small AC Offgrid Home
Medium AC Offgrid Home
Large AC Offgrid Home
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