Calculating your Energy Needs

I apologize for taking a hiatus over the holidays, but the solar process is slow going. After signing in November we finally anticipate install to start sometime in February. We have already made our first payments and anticipate claiming the tax credit when we file our taxes this year. As soon as all the permits are finalized we schedule install, mother nature willing since we need temperatures above 30 degrees to install panels on the roof. My blog will go into detail on the process in order and the full timing but for now first things first...

This post and the post to follow will be the not so fun posts involving math but essential steps to get your solar system in place to start saving money and the environment.

Photo compliments of Everblue Training Institute.

One of the first things you should do when you begin researching solar energy is to calculate your energy needs so that you can right size your solar system.  To calculate the size of system needed you must know your average electric use over the past 12 months. This will give you the most accurate consumption for your family. To find this information I went through my electric bills. The graph attached was found in a DTE electric bill.  It details 12 months of average daily electric use in kilowatt hours. To find out monthly usage you have to multiply the average daily use by the number of days in that month. For example this November we used 30.3 average wattage per day. To find Novembers monthly usage you must multiply 30.3 watts/day * 30 days in November which totalled 909 watts used in November. To get the average monthly usage for the last year you caculate the average monthly usage for each month for the past 12 months. Then you add them all up and then divide by 12. Our average monthly usage is 980 watts per month and our yearly usage is approximately 11,772 watts per year.

There are a number of variables that will effect your energy use and production. One that has changed ours is the fact that last winter we ran our electric hot tub all winter, this year we winterized it. While waiting on our panel install I recalculated our energy use not running the hot tub this year in October, November and December so far our average monthly use decreased 31 watts! This changes our yearly use to 11,352 watts. This will actually cause our rated system to cover more of our energy needs... precisely 3% more than we anticipated and winter isn't over yet.

My next post I will talk about panel size and how to take the monthly and yearly usage that was calculated and determine your system size. This will include the discussion of electric providers, laws and regulations regarding solar panel installation. Believe me there is more to it than I ever imagined!

Photo compliments of us.sunpower.com