One of the most common questions we get is: “How much solar power do I need?” The answer is pretty complex, and frankly, most people approach it from the wrong angle when they start to look into solar.
If you want to run through calculations yourself to determine the size of the solar power system you should get for your specific circumstances, you’ll want to figure out the main constraints on the project and use those restrictions as the starting point for the design. You can approach the project from two angles:

1) How much money you’re prepared to spend.

2) How much electricity your household uses.

Take into consideration other sizing factors and common stumbling blocks that may impact how to size a solar system:

1) Local levels of sun exposure

2) Orientation of the array (tilt angle)

3) Plans for future expansion

Before you begin to size a solar system, follow these steps to determine your home’s average electricity consumption and PV needs:

1. Calculate Your kWh Usage

1) Gather the kilowatt-hours (kWh) usage from your electric bill. We will assume it is quarterly. Look at how many kWh’s you have used in the previous 4 quarters. The information will be on your bill–look for usage over time and add up the last 4 quarters. That is how many kWh’s of electricity you use per year. Let’s imagine you use 6250 kWh per year.
2) Figure your daily kWh usage. Divide your [annual kWh’s] by 365. That is your daily usage. In this example it comes out as 17kWh’s per day.

2. Look Up Your Peak Sun Hours

Average peak sun hours vary greatly depending on your location and local climate. You’ll want to determine how may peak hours of sunlight you’ll get so you can make the most of the solar power:
1) Look up your peak sun hours, through the sun hours chart below to determine the number of hours per day the sun produces peak sunlight.
2) Find the nearest city to you and write down the daily average of peak sun hours.

3. Calculate the Watts of Your Solar System

To figure out how much solar panel you need, take your daily kWh energy requirement and divide it by your peak sun hours to get the kW output. Then divide the kW output by your panel’s efficiency to get the estimated number of solar panels you’ll need for your system.
(Daily kWh ÷ average sun hours) x 1.15 efficiency factor = DC solar system size

For example, if you live in Florida, you average 4.5 peak sunlight hours per day and you need 17kWh DC per day.
(17 kWh ÷ 4.5 sun hours) x 1.15 efficiency factor = 4.3 kW DC solar system size required

Using the example above with a 4.3 kW DC system, you can multiply this number by 1,000 to confirm that you need how many watts of solar system.
4.3 kWh x 1000 (convert to watts) = 4300 watts solar panel required

ECO-WORTHY offers high performing solar panel kits and dependable customer service. Here are a few viable options to consider after you size a solar system.

ECO-WORTHY Off Grid Solar Kits Guide

Of course, if all this talk of calculation is totally confusing you, then we suggest that you can contact us using email or LiveChat. This will allow you to talk directly to an expert who can explain all the ins and outs of system sizing with you and recommend how big a solar power system and how many solar panels you’ll need based on your requirements and circumstances.

Appliance Consumption Table

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

3250

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

900

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