Estimating the Effects of Tilt and Azimuth on Solar Installation

Warning, this is for the more advanced DIY solar fans.
I was recently discussing our solar project with a friend who is looking at homes in Atlanta and wants to factor in the feasibility of a solar PV installation.  In trying to find a tool to calculate the impact of roof pitch (aka tilt) and mounting angle away from due south (aka azimuth), I came across a tool I hadn’t used in over a year, PVwatts.  If you are at the point of seriously considering an installation on your own home, I highly recommend that you get a solar site survey by a professional solar contractor like we did When you are looking at a new house, getting a quick ballpark estimate of how the roof pitch and orientation would impact a solar installation can help you factor in the potential solar resource for different homes.

Enter the zipcode to load in the location specific information
Once you’ve selected your location, click on Send to PVWatts

In order to fill out the details in the PVWatts, you will need to estimate the roof pitch (tilt) and the orientation (azimuth).  Use Google Maps Satellite View or Bing Birds Eye View to get an idea of the roof orientation.

Plug that into PVWatts and you can get an estimate for the production.   The results from PVWatts were very similar to the data provided by our solar contractor as a result of our solar site survey using a Solar Pathfinder.  Also don’t forget to consider shading.  I love big tall trees, but they do mess up solar production if they are in the wrong places.

Happy Greening!

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  1. Really great idea. Thanks for the tips. Love the point about the solar water heating system. We are looking into installing a solar system that sits on our roof and generates electricity during the day for the night.

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