To size a wind power renewable energy system, you first have to determine your energy budget.
In order to complete an energy budget you will need to know how much power typical appliances use. What follows is a chart to help you.
AC Appliances Typical Energy Usage in Watts
Toaster Oven 1500
VCR 35
Well Pump 800
Sewing Machine 87
Satellite TV 50
Refrigerator/freezer 460
Vacuum 1125
Circular Saw 1500
Hair Dryer 1500
Jigsaw 300
Computer 100
Laptop 60
Monitor 60
27” TV 200
DVD 14
Drill 800
Microwave oven 1245
Compact fluorescent 13
Battery Charger 25
Blender/mixer 350
Belt Sander 800
DC Appliance Energy Usage
Appliance Watts
Cell Phone 4
Motor (small) 65
Sunfrost refrigerator 13
Radio 15
Stereo 30
Water Pump 50
VCR 15
14” Color TV 75
Battery Charger 7
Inverter Standby 5
Halogen Light 20
Now that you know how much energy your appliances use you can figure out your total energy usage per week, and per month.
In order to do this, simply figure out how many hours each device is used each day. Multiply this number by the number of watts that device uses and you will come up with the watt-hours of usage. Add all of the totals together to come up with your total watt-hours of usage for the week, and for the month.
Keep these numbers with your notes; you will use them to design your charging capacity, battery bank and inverter sizing.
Figuring out your own energy usage
Take the numbers you got from your own appliances or use the numbers we provided and work out your own energy budget.
Example:
| Appliance | Rated Wattage (A) | Hours Used per day (B) | Watt-Hours (A) x (B) per day |
| Satellite TV | 50 | 5 | 250 |
| Computer | 100 | 5 | 500 |
| Laptop | 60 | 5 | 300 |
| Stereo | 30 | 2 | 60 |
| Fuorescent light | 13 | 10 | 130 |
Add as many items as it takes to complete your inventory. It should be noted that most households use approximately 20 Kilowatt hours per day on average.
Your new wind-powered renewable energy system would have to be very large to compensate for this high level of usage. A typical home made wind generator is only going to produce about 1 Kilowatt (1000 watts) of power. This is a wind turbine with blades 4 feet long, making a blade outside diameter of 8 feet.
Through conservation and buying newer more energy efficient appliances you can achieve the goal of living off the grid. It just takes some time and effort on your part. You can live on a total family usage of about 2 or 3 Kilowatt-hour per day and live a relatively normal life, with satellite TV, satellite internet, DVD’s, lights etc. It can be done.
Some questions answered
Once I know how much power I will need to run my home, how will I figure out how much power production I need?
Answer: You figured out how much power you use in the earlier exercise. You should be aiming for around 10 kilowatt hours per day. You could actually run your entire home on just under 3 kilowatt hours per day with energy conservation measures
The power formula goes like this:
System Power = (Wind Speed ^3) (Blade Diameter ^2) x .00478
Wind Speed is measured in miles per hour.
Blade Diameter is measured in feet.
Power is measured in Watts
It is easy to figure out your blade diameter. A widely used 8 foot blade diameter has been proved with great success.
To find your wind speed you will have to find a wind speed chart, or monitor your own wind speed for a while to obtain your own readings.
Here is a source of wind speed data.
Let’s say your average wind speed is about 12 mph, which is pretty good. Plug that into your formula too. It would look something like this:
System Power = (12^3) (8^2) x .00478 = (1728) (64 ) x .00478
= 110592 x .00478 = 528 watts
Multiply this by 24 hours and you will have 12672 watt-hours, or about 1.2 kilowatt hours per day.
Wind speed has the greatest impact on power output since it is cubed in the previous formula. You can’t change wind speed though. You either have it or you don’t.
This brings up our next question.
Should I build one large wind generator, or several small ones?
Answer: Obviously blade diameter can have a huge impact on the amount of power that your homemade wind generator produces. There are a few concerns though. Yes, you could put up a homemade wind generator with a 20 foot blade diameter, but the forces of the wind at storm levels would demand a very substantial tower. Also, if you live in a populated area your neighbor might not appreciate a huge wind generator in your backyard. Ask first.
Some areas even have bylaws about this stuff, do some research first and find out what you can and cannot do.
Usually it is much easier to find towers for several smaller wind generators and parts to build them too. If you have areas on your property that are clear in different directions, put up several homemade wind generators to capture the wind more effectively from different directions with much smaller towers.
One final thing, when you have several homemade wind generators you can shut one down for cleaning or maintenance (or if a storm does this for you) and your other ones are still providing power.
A lot less work in the long run, and less headaches with a smaller system.
Get the full scoop on How to Build Your Own Home Made Wind Generator
