How to estimate a Solar Grid-Tie System

Loading ...

July 20th, 2010 Solar Power

As I was researching ideas to turn my rental house into an alternative energy consuming living space, I ran across some formulas that I found very helpful to help me determine what size solar power system I wanted to add to my home. Hopefully this can be a good start for anyone else thinking about doing the same thing.

Step 1:
Find the average monthly electrical use from your electricity bill. This number will be in kWH (kilowatt-hours). Record average monthly kWH electrical use: __________kWH

Step 2:
Multiply this average monthly kWH electrical use by the percentage you want the solar system to produce: __________kWH ie: 1000kWH X 50% = 500kWH
NOTE: most homes consume between 20,000 to 50,000kWH a day on average.

Step3:
Divide by 30 for the daily output from your solar power system: __________kW

Step4:
Divide by the daily average sun hours for your location: __________kW 6 in Sun Belt, 4in NE / NW

Step5:
Divide by 75% to compensate for system efficiency: __________kW

Step6:
DONE: Take your final kW number, and this is the smallest size system you should build. You can make it bigger if you want to account for margins of error.