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 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
