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Ivylog's avatar
Ivylog
Explorer III
Oct 21, 2018

DIY 700W solar install.

I just bought 10 102W First Solar series4 thin film panels ($550) but only have room for 7 along drivers side of my roof. May add the other 3 to passenger side if getting by them is not to much of a pain. They are 2'X4' 80V and 1.5A so I bought a Outback Power FlexMax 60A 150V MPPT controller. Going to make my own tilting mounts fastened to the top of the raised rail on my 08 Navigator. Should have less than $1000 in this installation.

The alum raised rails along each side makes it easy to attach a pivot on the inside near the top of it...a 2” piece of 1.5” alum channel. The panels are frame-less so I’ll clip each to two PT wooden battens that fit/pivot in the 1.5” alum channels. When traveling they will be angled down towards the middle of the roof...have not decided if I need to hold them down while traveling. Angled down is also the best position when we snowbird each winter.

The 100W frameless panels that are 2' X 4' so they will fit besides my AC units and hopefully will not be shaded by them. Going to silicone and clip the panels to the PT battens.





Getting the panels up on the roof was a challenge but fortunately I had a canvas bag with straps that they would fit in. Used a rope to pull the bag up the back of the MH.

Need to carefully clean the panels.
Class A
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    Oct 23, 2018
    OK Good luck.

    JMHO That the panels are a sail and need to securely fastened down at all times.
  • Ivylog's avatar
    Ivylog
    Explorer III
    Oct 23, 2018
    Cross winds lifting the panels: In the first picture you can see that the bottom of the raised rail is so well sealed that water only runs off the roof where there is a small gap in the rubber seal. Maybe when tilted up a cross wind could be a problem...note to self, do not tilt up in heavy winds. It would be fairly easy to run a cord through the grey tank vent and over the ends or the mounting boards using a eye bolt at each end (screwed into the roof) to hold them down when raised.

    To tilt up I have seven 20” long notched wooden 1X1 that clip on to the panels. I’d rather not drill into the roof so I’m going to see if hold downs are really necessary.
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    Oct 23, 2018
    Clever installation.

    Why aren't you concerned about cross winds lifting those panels when stopped?

    How are you going to support the panels when tilted?

    A hold down will ensure they don't move while driving, stopped or tilted.
  • Ivylog's avatar
    Ivylog
    Explorer III
    Oct 23, 2018
    In my first picture you can see that the black front cap is almost as high as the side rails creating a low pressure area at the front of the coach...airflow along the front of the roof may actually be forward moving. The most efficient wing is long and thin...a sailplane wing. These panels are the opposite...fat and short so I’m not to worried about them flying away. If anything, the rear panels have down forcing air. Time will tell.
  • MrWizard's avatar
    MrWizard
    Moderator
    Oct 23, 2018
    place a card vertical in front of the deck

    same thing he has done with his block at the front of the panels

    NO Edge for air to get under
  • Busskipper's avatar
    Busskipper
    Explorer
    Oct 23, 2018
    MrWizard wrote:
    'No Air' ?

    they are Not in a Vacuum !
    there is air, dense NON-moving air
    no air moving underneath, means little to NO pressure differential
    the air on top, coming over the raised front should provide down pressure

    remembering my high school physics !


    I did not fail Physics :)

    Just try to understand how it works,

    When high speed winds are blown over any kind of roof the pressure of wind reduces there but the air pressure under the roof is still the same which pushes the roof and results in the roof to blow off. That's why/how winds blow off roofs - also why Hurricane Straps are used/required on all the roofs in the Gulf and Florida strap them to the walls and strap the walls to the Floors and the Floors to the Footings.

    Just plain and simple,

    Dick, just PM me when the paper flies out, as it will fly out.

    Bill

    Easiest way to watch this work is with high speed air over the top of a deck of cards they will all lift and be blown away, just simple Physics.
  • Ivylog's avatar
    Ivylog
    Explorer III
    Oct 22, 2018
    MrWizard wrote:
    '
    no air moving underneath, means little to NO pressure differential
    the air on top, coming over the raised front should provide down pressure.

    X2 and it will probably be Christmas before I take it out again...will report back then on the test papers being under the supports or not.
  • MrWizard's avatar
    MrWizard
    Moderator
    Oct 22, 2018
    'No Air' ?

    they are Not in a Vacuum !
    there is air, dense NON-moving air
    no air moving underneath, means little to NO pressure differential
    the air on top, coming over the raised front should provide down pressure

    remembering my high school physics !
  • Busskipper's avatar
    Busskipper
    Explorer
    Oct 22, 2018
    Ivylog wrote:
    Bill, as a pilot of over 45 years I even remember the B principle BUT there is a little more to how a wing create lift...angle of attack being very important and the high pressure created by/under it. Some people think lift is due solely to the camber of the wing...the B principle. Sorry but it’s not that simple. A cambered wing only increases the differences in pressure that create lift...with no high pressure under the panels, there will be very little lift. The most important item for lift is the angle of attack of the wing...the panels probably have a negative angle of attack once the air off the front front finally comes back down.

    I will put small pieces of paper between the supports and the roof. If they are still there after a short high speed run I’ll not worry about holding them down.


    But if no air is under the panel it will lift as the speed will create the pressure differential - Right?

    That's why things fly out/off the back of a truck if not tied down.

    I owned a lot of trucks back in the day and Sh*t flew off if not tied down - Flew off - not from anything else but air pressure differentials.

    Sure it will all work out - Mine are Bolted and stationary. :)

    Just keep your eyes on it.

    Bill
  • Ivylog's avatar
    Ivylog
    Explorer III
    Oct 22, 2018
    Bill, as a pilot of over 45 years I even remember the B principle BUT there is a little more to how a wing create lift...angle of attack being very important and the high pressure created by/under it. Some people think lift is due solely to the camber of the wing...the B principle. Sorry but it’s not that simple. A cambered wing only increases the differences in pressure that create lift...with no high pressure under the panels, there will be very little lift. The most important item for lift is the angle of attack of the wing...the panels probably have a negative angle of attack once the air off the front front finally comes back down.

    I will put small pieces of paper between the supports and the roof. If they are still there after a short high speed run I’ll not worry about holding them down.

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