A Shaded panel
- Thread starter peter247
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Rednecktek
Solar Wizard
It will bring down any other panels it's in series with it, but not any panels in parallel, so it depends on your panel layout.
12VoltInstalls
life passes by too quickly to not live in freedom
How many panels? What configuration?
I would be inclined to configure differently (a parallel config) if feasible. Or basically move the panel(s) effected so it doesn’t matter.
I'm planning for 3 x 300w panels in series , but 1 panel will be shaded around midday , so is it best to have a 2 x 300 w array and maybe put the other panel which is going to be shaded on it's own controller ?
I'm thinking of setting up a time laps camera to find how much that tree is going to be a problem.
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Some panels have smarts in them and the shaded panel only drops the output of that panel. Some even have the ability to drop the output of only the shaded portion of the panel that’s shaded…
What panels do you have?
What panels do you have?
12VoltInstalls
life passes by too quickly to not live in freedom
I’d say that would work.
I’d probably use four panels - two in series to one controller, and two parallel to the other and positioning to mitigate. (You don’t need the parallel panels to be anywhere nearby each other (within reason))
You could position the 4th panel for best afternoon sun, for example. This is all assuming the panels have high enough voltage to be useful mppt
Limited space !!! , a single car garage 5m long east and west facing , so a 300w panel is 1m x 1.5m therefore will just get 3 panels to fit .
RCinFLA
Solar Wizard
- Joined
- Jun 21, 2020
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It depends on your series string total voltage and the minimum acceptable MPPT voltage for your system.
It also depends on condition of bypass diodes in panels.
Easiest to assume any panel with some shading will totally drop out and will have a three-diode voltage drop, say -3v drop. If the sum of the illuminated series panel mppt voltage - (3v x number of shaded panels) is still greater than your minimum MPPT system voltage the string will still produce output at a reduced power.
I mentioned bypass diode condition because often manufacturers put insufficient poor quality bypass diodes in the panel. When bypass diode is bypassing it carries panel current. This current x diode voltage drop is heating on the diode. If you have a 9 amp Imp panel and diode has 0.9v to 1.1v drop it will be dissipating 10 watts of heat. A small pellet bypass diode will cook and self destruct.
A cheap poor quality panel may put diodes in parallel under the assumption it can carry more current. This is bad engineering as diode with lowest voltage drop will take most of current. As diode gets hot its voltage drop reduces and it takes even more current so parallel diodes is a downward spiral to full destruction.
A good panel has large bypass diodes packaged in something like a power transistor case with some heat sinking provided.
A bypass diode is usually put across every down and back cell row pair in a panel and are located in panel junction box. For example, if panel is 10 cells long x 6 cells wide (60 cell panel) it will have three bypass diodes in junction box for three down and back row pairs.
If one bypass diode on any shaded section burns out to open state you will get zero output from total series array of panels.
A partially shaded panel can produce some output but it is difficult to predict how much.
It also depends on condition of bypass diodes in panels.
Easiest to assume any panel with some shading will totally drop out and will have a three-diode voltage drop, say -3v drop. If the sum of the illuminated series panel mppt voltage - (3v x number of shaded panels) is still greater than your minimum MPPT system voltage the string will still produce output at a reduced power.
I mentioned bypass diode condition because often manufacturers put insufficient poor quality bypass diodes in the panel. When bypass diode is bypassing it carries panel current. This current x diode voltage drop is heating on the diode. If you have a 9 amp Imp panel and diode has 0.9v to 1.1v drop it will be dissipating 10 watts of heat. A small pellet bypass diode will cook and self destruct.
A cheap poor quality panel may put diodes in parallel under the assumption it can carry more current. This is bad engineering as diode with lowest voltage drop will take most of current. As diode gets hot its voltage drop reduces and it takes even more current so parallel diodes is a downward spiral to full destruction.
A good panel has large bypass diodes packaged in something like a power transistor case with some heat sinking provided.
A bypass diode is usually put across every down and back cell row pair in a panel and are located in panel junction box. For example, if panel is 10 cells long x 6 cells wide (60 cell panel) it will have three bypass diodes in junction box for three down and back row pairs.
If one bypass diode on any shaded section burns out to open state you will get zero output from total series array of panels.
A partially shaded panel can produce some output but it is difficult to predict how much.
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Rednecktek
Solar Wizard
With that I'd say a 3p is the optimum way to go... or a larger garage.
That is under consideration .Just use a chainsaw. Hehe
12VoltInstalls
life passes by too quickly to not live in freedom
Rotate 90* and presto! 4 panels fit.With that I'd say a 3p is the optimum way to go... or a larger garage.
(unless that’s for a ken’n’barbie garage)
No , only about 1.3m of slope each side , so can't do that.
So chainsaw it is then
12VoltInstalls
life passes by too quickly to not live in freedom
A single car garage is wider than 102” so the pitch should be much longer than 51”
Unless the garage is for a bmw isetta?
12VoltInstalls
life passes by too quickly to not live in freedom
That is what the tape measure says , external side to side . But I would guess 4 - 5 inch wide ? pre cast panel walls and a 6ft lift door ? with a 16 inch pitch
