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Powering America from Trump’s ‘solar’ border wall: how many kilowatts …?

June 7th, 2017 · 2 Comments

One can’t step away from the news for a moment without something shocking. Just in: Donald Trump has evidently embraced the idea (certainly telling people it was his, but no …) of putting solar panels on the (likely never to be built) border wall.

Put aside any other issue, just how much electricity might this create?

Some very simple calculations (after the fold).

  • If the solar panels cover the top of the wall, this would produce in the range of 23 million kilowatt hours (kWh) per day, on average, through the year (or 23,100 megawatt hours (mWh) or 23.1 gigawatt hours (gWh).  Per year, 8,431 gWh or 8.4 terrawatt hours (tWh).
  • If solar panels were to cover the surface facing south (putting aside issues of angling or tracking), this could be increased roughly by an order of magnitude — e.g., in the range of 84 tWh/year.

Total US electricity demand is about 4000 terrawatt hours/year, thus Trump’s having solar on the top of Trump’s wall would would provide roughly 0.2 percent of total US electricity supply and about 2 percent if the entire wall were covered with solar panels when (okay, IF) constructed.

Notes:

This top of the wall (back of the envelope) calculation derived this path:

  • Assumptions:
    • 3850 kilometer long wall
    • 1 meter wide solar panels on its top
      • Thus, 3,850,000 sq meters of solar panels
    • On average, 6 kilowatt hours/day per square meter
  • Results
    • 23,100,000 kWh/day
      • 23,100 mWh/day
      • 23 gWh/day
    • 8431.5 gWh /year
      • 8.4315 Terrawatt hours/year

The ‘cover the south face’ is simply a 10x calculation (1 meter on top, 9 meters on south face of wall) that doesn’t account for angling the panels, potential shading, etc that would reduce productivity. To a certain extent, production could be enhanced through solar tracking systems for a portion of the solar panels.

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2 responses so far ↓

  • 1 Longjohn // Jun 23, 2017 at 2:09 am

    Have any actual Engineers done these calculations? These are really Best Case Scenario calculations because they don’t take into account the losses in tying all the panels together in parallel or the costs of hundreds of substations to do so.

    Agree — should have put in that this is ‘best case’ … so of the linked items seek to control for shading, etc, more than the ‘back of the envelope’ of this post.

    Solar farms are laid out in some sort of grid array with a centralized location to ‘collect’ all the parallel arrays of panels. They are all roughly the same width as length like 1 KM x 1 KM NOT . 07 KM x 3850 KM like with a wall …..

    You are going to end up 50% or more cut in efficiency just trying to tie everything together and get it into the Grid.

    You’d be infinitely better off just investing that money into several traditionally (AKA CORRECTLY) laid out solar farms

    Agreed … would also say, due to T&D / resiliency, that also ‘infinitely better off’ just having a mix of rooftop (residential, commercial) + ‘traditionally laid out solar farms’.

    like these

    https://www.google.com/search?q=solar+farm+photos&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwio5peSwNPUAhXs7IMKHUm3CR8QsAQILw&biw=1920&bih=988

    And, by the way, for ‘fun’ — with ‘rolling chicken coops’ (https://foodtank.com/news/2014/03/chicken-tractors-a-simple-innovation-with-a-big-payoff/) / sheep / such munching away to keep vegetation undercontrol under solar panels.

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    […] Donald Trump has created some buzz with discussing the potential for making the Mexico border wall a power plant:  covering it with solar panels. […]