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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 solar panel calculator below TWICE. Compare and adjust your plans according to your budget and lifestyle.



Off-Grid Solar Panel Calculator

This provides a rough estimate of your solar needs. For a more precise calculation, please give us a call at 1-800-472-1142.

Wholesale Solar Off-Grid System Size Calculator
1. What's the most electricity you might use in a month?

Look at your past electric bills and find the month with the highest usage (often summer or winter, depending on cooling/heating needs in your area). The bill should show you the number of kilowatt-hours (kWh) used that 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 Calculator OR (PDF) or measure the power usage of each appliance with a Kill A Watt Meter. The Neurio Home Energy Monitor also give excellent real-time monitoring of your energy usage. Multiply results by 30 (for a monthly total) and divide by 1000 (to convert watt-hours to kilowatt-hours).
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. This gives you the annual average. If you will use your system during the winter, subtract 1.5 hours from the annual average to account for decreased sunlight during those months. This ensures your system will be properly sized to provide year-round power, even during darker months.
Minimum System Size:

Approximate Solar Panel Wattage:

Approximate Number of Solar Panels Needed:


For 30 Kyocera 140-watt solar panels to produce 4,200 watts..... 4,200 divided by 140(watts per panel) = number of solar panels needed.
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
solar insolation 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.

Load Evaluation Calculator

Wholesale Solar Load Evaluation Calculator
Appliance Quantity Watts
(V x A)
Mult. * 1.5 for AC conversion
Hours On per Day Watt Hours per Day


Total Watt Hours per Day:
Watts
Watt Hours Required Assuming Inherent Efficiency Loss:
Watts

Appliance
Watts
Appliance
Watts
Appliance
Watts
Kitchen
Living Room
Tools
Blender
500
Bluray Player
15
Band Saw - 14"
1100
Can Opener
150
Cable Box
35
Belt Sander - 3"
1000
Coffee Machine
1000
DVD Player
15
Chain Saw - 12"
1100
Dishwasher
1200-1500
TV - LCD
150
Circular Saw - 7-1/4"
900
Espresso Machine
800
TV - Plasma
200
Circular Saw 8-1/4"
1400
Freezer - Upright - 15 cu. ft.
1240 Wh/Day**
Satellite Dish
25
Disc Sander - 9"
1200
Freezer - Chest - 15 cu. ft.
1080 Wh/Day**
Stereo Receiver
450
Drill - 1/4"
250
Fridge - 20 cu. ft. (AC)
1411 Wh/day**
Video Game Console
150
Drill - 1/2"
750
Fridge -16 cu. ft. (AC)
1200 Wh/day**
Lights
Drill - 1"
1000
Garbage Disposal
450
CFL Bulb - 40 Watt Equivalent
11
Hedge Trimmer
450
Kettle - Electric
1200
CFL Bulb - 60 Watt Equivalent
18
Weed Eater
500
Microwave
1000
CFL Bulb - 75 Watt Equivalent
20
Misc.
Oven - Electric
1200
CFL Bulb - 100 Watt Equivalent
30
Clock Radio
7
Toaster
850
Compact Fluorescent 20 Watt
22
Curling Iron
150
Toaster Oven
1200
Compact Fluorescent 25 Watt
28
Dehumidifier
280
Stand Mixer
300
Halogen - 40 Watt
40
Electric Shaver
15
Heating/Cooling
Incandescent 50 Watt
50
Electric Blanket
200
Box Fan
200
Incandescent 100 Watt
100
Hair Dryer
1500
Ceiling Fan
120
LED Bulb - 40 Watt Equivalent
10
Humidifier
200
Central Air Conditioner - 24,000 BTU NA
3800
LED Bulb - 60 Watt Equivalent
13
Radiotelephone - Receive
5
Central Air Conditioner - 10,000 BTU NA
1200
LED Bulb - 75 watt equivalent
18
Radiotelephone - Transmit
75
Furnace Fan Blower
800
LED Bulb - 100 Watt Equivalent
23
Sewing Machine
100
Space Heater NA
1500
Office
Vacuum
1000
Tankless Water Heater - Electric
18000
Desktop Computer (Standard)
200

Note: TVs, Computers, and other devices left plugged in but not turned on still draw power.

**To estimate the number of hours that a refrigerator actually operates at its maximum wattage, divide the total time the refrigerator is plugged in by three. Refrigerators, although turned "on" all the time, actually cycle on and off as needed to maintain interior temperatures.

Water Heater - Electric 4500 Desktop Computer (Gaming) 500
Window Air Conditioner 10,000 BTU NA 1200 Laptop 100
Window Air Conditioner 12,000 BTU NA
3250
LCD Monitor
100
Well Pump - 1/3 1HP
750
Modem
7
Laundry
Paper Shredder
150
Clothes Dryer - Electric
3000
Printer
100
Clothes Dryer - Gas
1800
Router
7
Clothes Washer
800
Smart Phone - Recharge
6
Iron
1200
Tablet - Recharge
8

* The daily energy values listed here are for the most efficient units in their class and the information was obtained from Consumer Guide to Home and the General Electric website.