Living Sustainably
in the shadow of climate change

March 2015
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A solar day
Filed under: General, Solar Power
Posted by: Guy @ 10:29 am

Recently I was talking with a friend of mine whom I had assumed was somewhat knowledgeable about solar energy.  I was surprised when he made the assertion that “solar panels only produce power in direct sunlight”.  I corrected him and informed him that even on heavily overcast days, my solar array can produce over 3 kWh.  But on a typical sunny day like yesterday, September 20 you can see the power curve shows power being generated before and after sun strikes my solar array which is facing West at 270°.  Sunrise on this day was at 6:25 AM and it set at 6:38 PM, and my array was producing power for every minute of this time.

Total amount of power produced on this day was 22.9 kWH and the sun first hit the solar array at around 9:20 AM and Dropped behind the trees at around 5:30 PM (17:30).  As you can see my solar array was producing hundreds of Watts before and after the sun was shining directly on the panels.

Compare this with the power curve from today which was heavily overcast with the sun barely making an appearance, yet the array produced 9.71kWH.

4 Responses to “A solar day”

  1. rj Says:
    With the ability to generate electricity becoming more mainstream and affordable, the next challenge is storage. I believe the next Edison or Steve Jobs will imagine and implement a practical way of saving large amounts of electrical energy, if even for a relatively short time. I suspect it will come, it will be relatively simple and it will be revolutionary in it’s impact. It might involve kinetic or thermal energy transfer or something besides chemical means.
  2. Guy Says:
    When I met the design engineers that developed the battery for the Chevy Volt, they explained that from the very beginning they were considering secondary uses for those batteries after they were no longer considered “automotive grade”. A logical use for them turns out to be storage for Residential scale solar power systems. I expect in another five or six years we will see these batteries being repurposed when they are removed from older electric vehicles, since they will have plenty of remaining life in them.
  3. rj Says:
    Here is an interesting story on compressed air storage of energy. Mechanical Storage of Energy
  4. Brian Edwards Says:
    I am new to the idea of going solar, it is natural to have some questions.I might be asking myself, how do I go solar for my home/business, and where do I should start? Who can I trust to make this long term investment worthwhile? I used this service to compare free quotes from local solar installers and I was able to save a lot of money on my system. I encourage anyone who is looking to go solar to do the same, it took me 30 seconds and it’s free! Here is the link to their website: