Solarize Plano Project - Homework Assignment

January 15, 2014

To be prepared for the Information Session meetings, you will need to invest some time in preparation for two items - (1) determine the orientation of your residence, and (2) determine for your home, three potential PV solar system sizes - we will call them SMALL, MEDIUM, and LARGE.

If you have any questions while doing this homework, please contact Larry Howe (rlhowejr@gmail.com) or Bob Litwins (rlitwins@gmail.com) with your questions.

1. Determine the orientation of your residence:

The ideal position to install solar panels is on a south-facing roof, however, even an east-west configured roof can still produce sufficient electricity to make it worth your while to go solar. Most installations in Plano will be roof mounted so understanding your home’s directional orientation and consideration for any surrounding structures or trees that could cause an undesirable amount of shading is important. While a site survey performed by the solar installation company will ultimately determine the suitability of your home’s roof and shading impacts, it is important for you to do some preliminary assessments.

It is recommended that you use Google Maps to input your home address and then look at the satellite view to determine your home’s directional orientation and see how much desirable roof area you have. Normally, the top of the Google Maps page faces north.

2. Calculate three potential PV solar system sizes:

Knowing an estimate for how much electricity you use on an annual basis is one of the first key steps in determining what size of PV Solar system would be most appropriate for your situation. For this homework exercise, you will calculate a small, medium, and large size system for your situation.

SMALL means a PV solar system size (measured in kW) that will provide approximately 33% of your total annual energy usage.

MEDIUM means a PV solar system size (measured in kW) that will provide approximately 50% of your total annual energy usage.

LARGE means a PV solar system size (measured in kW) that will provide approximately 67% of your total annual energy usage.

Recall - the estimate for your annual electricity usage is determined by adding up the per month kWh usage for the last 12 months.  This information is available on your electricity bills, or possibly available when you log into your account on your electricity company's website.  (See note B below if you are having trouble locating this information.)

Knowing these three potential systems sizes in kW for your specific home, and with the information to be discussed during the Information Session meetings, you will be able to calculate estimated system costs.

The basic calculations to perform before the meeting are:

1. for the SMALL system size determination, multiply your total annual energy usage by 33%. Then take this number and divide it by 1400, which is the estimated annual production in kWh from a 1KW south facing PV system in North Texas.  As an example, assuming your annual energy usage is 15,000 kWh:

15,000 * 0.33 = 4,950

4,950 / 1,400 = 3.5 kW PV system

2. for the MEDIUM system size determination, multiply your total annual energy usage by 50%. Using the example from above.

15,000 * 0.50 = 7,500

7,500 / 1,400 = 5.4 kW PV system

3. for the LARGE system size determination, multiply your total annual energy usage by 67%. Using the example from above.

15,000 * 0.67 = 10,050

10,050 / 1,400 = 7.2 kW PV system

Be sure to bring the results from your calculations for SMALL, MEDIUM, and LARGE to the meeting along with a calculator and something to take notes with.

Best Regards & Shine On!

Larry Howe & Bob Litwins, Plano Solar Advocates volunteers

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Note:

A. If you are having trouble locating the last 12 months of energy consumption, you may also try contacting Oncor's Service Request line at 1.888.313.6862 (see http://www.oncor.com/EN/Pages/I-Need-To.aspx) and asking for consumption or usage history.  If you live in the CoServ service area, try calling the CoServ Customer Service number and inquiring about usage history for your address.

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