Solar Panels and Your Sun Number

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The sun number is the rating for the solar capabilities of your house. The closer your home’s score is to 100, the more suitable it will be for solar technology. Let’s look at the factors going into the rating system when you’re considering installing solar panels.

Sun Numbers

Here are some of the elements determining the sun number score:

  • Direction your roof facesSolar panels positioned on your roof facing true south when you live north of the equator will have the best results for green energy production and savings. Solar panels will produce about 20% less electricity when your roof faces directly east or west.
  • Slope or pitch of your roof – Solar panels produce the most energy when placed exactly perpendicular to the sun at an angle between 30 degrees and 45 degrees. Your local solar installation company can help you with the optimal angle as it can vary between winter and summer.
  • The area of your roof available to support solar panels – Steep roofs may result in solar panels being placed directly against the roof. Flat roofs will generally use a racking system for the optimal angle. Low angle roofs may require specialized racking.
  • Average number of sunny, partly cloudy, and overcast days – The Valley of the Sun averages about 299 sunny days per year. Between 36 and 72 days a year are overcast according to
  • What types of obstructions blocking sunlight – Tall buildings and tall trees can cast a shadow on your roof impacting how much sunlight can be captured by the solar panels. A small amount of shade can affect power output.
  • Amount of direct sunlight hitting the roof – Average peak sun hours can vary depending on the area you live in. There are about six hours of peak sun hours in metro Phoenix.
  • Cost of electricity – There’s a way to determine approximate electricity production by considering the angle, cost of electricity per kWh, and average annual solar radiation. The average price per kWh in the Valley of the Sun in 2021 ranged from $0.12 kWh to $0.15 kWh.
  • Cost of solar panel installation – It’s always best to use a local professional solar system installation company to mount panels on your roof to guarantee optimal energy production and safety.

Contact Cool Blew Solar for more information on how you can go solar now. Call our professionals valleywide at 623-234-2836. We’ll be happy to get you started!