150w folding flexible solar panels

Farmhat · Senior Member

150w folding flexible solar panels

woofta and precious · Senior Member

Cheapest I can see at the moment
www.ebay.com.au/itm/140W-FLEXIBLE-FOLDING-SOLAR-PANEL-KIT-MONO-CARAVAN-BOAT-CAMPING-POWER-BATTERY/362023128769

T1 Terry · Guru

The one yr warranty is a bit of a worry. Hopefully there are blocking diodes between each panel or they will be lucky to last the yr. Price looks good though

T1 Terry

Farmhat · Senior Member

T1 Terry wrote:
The one yr warranty is a bit of a worry. Hopefully there are blocking diodes between each panel or they will be lucky to last the yr. Price looks good though

T1 Terry

Thanks. sunyee-au has confirmed that they do have the blocking diodes.

woofta and precious, do you know if the 140w have the blocking diodes?

joe

T1 Terry · Guru

Just check they know the difference between bypass diodes and blocking diodes. Not many solar panel manufacturers fit blocking diodes these days so they would have been specially fitted and they would know the value of each diode if they had it specially fitted.

T1 Terry

Farmhat · Senior Member

T1 Terry wrote:
Just check they know the difference between bypass diodes and blocking diodes. Not many solar panel manufacturers fit blocking diodes these days so they would have been specially fitted and they would know the value of each diode if they had it specially fitted.
T1 Terry wrote:
The one yr warranty is a bit of a worry. Hopefully there are blocking diodes between each panel or they will be lucky to last the yr. Price looks good though

T1 Terry
T1 Terry

Thanks Terry. If not many solar manufacturers fit blocking diodes these days, can I assume that all their panels wont last a year? Is this the case just on flexible panels?

I would love an explanation about these 2 sorts of diodes to unconfuse me a bit if you wouldn't mind please. I don't want to buy something that would only last a year at those prices. Thanks

joe

T1 Terry · Guru

I'll give it a go :lol: Semi flexible panels use a different junction set up that passes more current at a lower resistance and therefore lower losses and greater output. The trade off is protection against back current flow.

While all the modules in all the panels are putting out their best output and the battery is accepting all they can give, there isn't a problem, the problem starts when the battery can no longer accept all the output. At this point the panel voltage is no longer tied to the battery voltage because the panel output is greater than the battery will accept without the voltage rising to a level that could damage the battery. The solar controller now starts turning the solar panel output on/off/on at a switching rate fast enough to hold the battery at a safe voltage. The longer the off part of the cycle, the higher the solar panel voltage reaches until it reaches the open circuit voltage.

At about this point theory and reality don't see eye to eye. Theoretically solar open circuit voltage has no current so it can do no damage, in reality the resistance in the cabling and joints produces a bit of voltage drop and that is all that is needed for the solar panel to again produce current.

Now this high voltage backed up by the combined current from all the solar panels in parallel has no where to go because the solar regulator won't allow it to flow through to the battery, so it looks for some where to go.

Every solar panel has a few less than perfect modules as part of the build, these actually produce more than the other modules but have less back current flow protection and this is the first place the high voltage back by the combined current goes. The module now becomes a heater because it can't match the combined output of all the modules in the string and finally the module breaks in pieces. Once that module has lost its circuit through it the remainder of that part of that panel has no path for the current to flow so that output is lost. The high voltage backed by the remaining combined current looks for the next weakest module and so the destruction continues until there are not enough still performing panel sections to produce enough current to burn out any more modules.

First off, a diode is just an electric current one way valve, it can flow through in one direction but not back the other way. Now for how the 2 different types of diode work. They are both the same type and size, a bypass diode works when the panels are in series and allows the current from the other panels to go through the diode rather than through the panel if for some reason that panel is not performing well enough to add to the voltage produced after that panel. This could be because of shade of a dirty panel. Basically, if the panel is producing voltage it will add to the string and the voltage after the panel will be higher than the voltage before the panel. The one way valve bit of the diode will not allow the current to flow from the higher voltage to the lower voltage. If the panel is not adding to the voltage string there is nothing to stop the flow through the one way valve so the current bypasses that panel. Clear as mud eh :lol:

A blocking diode does the same job but on the output of each panel. If the panel is producing the current will flow through the diode, if it is not producing the one way valve won't allow the current from the other panels to flow back into that panel ......

Breath deep and the head spinning will clear wink

T1 Terry

-- Edited by T1 Terry on Tuesday 24th of April 2018 01:50:35 PM

Farmhat · Senior Member

Well I did ask didn't I smile .

Thank you Terry for that explanation. Sure is appreciated.

It makes sense and I am sure many people will get some new knowledge from it.

I think I will take a chance on these panels. The weight on some of the larger conventional type portable panels is insane, having to lug these heavy things around can be a pia.

Now I will have to wait around for the first puff of wind to make sure these lightweights don't blow away, biggrin

joe

T1 Terry · Guru

Farmhat wrote:
Well I did ask didn't I .
Thank you Terry for that explanation. Sure is appreciated.
It makes sense and I am sure many people will get some new knowledge from it.
I think I will take a chance on these panels. The weight on some of the larger conventional type portable panels is insane, having to lug these heavy things around can be a pia.
Now I will have to wait around for the first puff of wind to make sure these lightweights don't blow away,
joe

Post a photo of the panels when you receive them and I'll guide you through the steps of fitting blocking diodes to save their lives. We even have the diodes here, had to buy 500 of them as this was the smallest quantity they'd sell the size we required :lol:

T1 Terry

oldtrack123 · Guru

T1 Terry wrote:
I'll give it a go :lol: Semi flexible panels use a different junction set up that passes more current at a lower resistance and therefore lower losses and greater output. The trade off is protection against back current flow.
While all the modules in all the panels are putting out their best output and the battery is accepting all they can give, there isn't a problem, the problem starts when the battery can no longer accept all the output. At this point the panel voltage is no longer tied to the battery voltage because the panel output is greater than the battery will accept without the voltage rising to a level that could damage the battery. The solar controller now starts turning the solar panel output on/off/on at a switching rate fast enough to hold the battery at a safe voltage. The longer the off part of the cycle, the higher the solar panel voltage reaches until it reaches the open circuit voltage.

[1]
At about this point theory and reality don't see eye to eye. Theoretically solar open circuit voltage has no current so it can do no damage, in reality the resistance in the cabling and joints produces a bit of voltage drop and that is all that is needed for the solar panel to again produce current.

Now this high voltage backed up by the combined current from all the solar panels in parallel has no where to go because the solar regulator won't allow it to flow through to the battery, so it looks for some where to go.
Every solar panel has a few less than perfect modules as part of the build, these actually produce more than the other modules but have less back current flow protection and this is the first place the high voltage back by the combined current goes. The module now becomes a heater because it can't match the combined output of all the modules in the string and finally the module breaks in pieces. Once that module has lost its circuit through it the remainder of that part of that panel has no path for the current to flow so that output is lost. The high voltage backed by the remaining combined current looks for the next weakest module and so the destruction continues until there are not enough still performing panel sections to produce enough current to burn out any more modules.

First off, a diode is just an electric current one way valve, it can flow through in one direction but not back the other way. Now for how the 2 different types of diode work. They are both the same type and size, a bypass diode works when the panels are in series and allows the current from the other panels to go through the diode rather than through the panel if for some reason that panel is not performing well enough to add to the voltage produced after that panel. This could be because of shade of a dirty panel. Basically, if the panel is producing voltage it will add to the string and the voltage after the panel will be higher than the voltage before the panel. The one way valve bit of the diode will not allow the current to flow from the higher voltage to the lower voltage. If the panel is not adding to the voltage string there is nothing to stop the flow through the one way valve so the current bypasses that panel. Clear as mud eh :lol:

A blocking diode does the same job but on the output of each panel. If the panel is producing the current will flow through the diode, if it is not producing the one way valve won't allow the current from the other panels to flow back into that panel ......
Breath deep and the head spinning will clear

T1 Terry

-- Edited by T1 Terry on Tuesday 24th of April 2018 01:50:35 PM

IF you had left out out your theory in [1] it would have been pretty good

You obviously still have a problem understanding Ohm's Law[ the basic law that all electrics work on]

But you do now seem to understand the reason why cell burn out problems are occurring with some brands of flexible panels and why the makers recommend they should not be connected in parallel

But it is not only when the battery is fully charged that the problem can occur

Shading of one panel has been shown to be a problem.

Simple reason ,shading reduces the panel's output voltage, poor reverse current blocking , panel with higher voltage feeds back into the shaded panel,hot spots /burn outs occur

biggrin

-- Edited by oldtrack123 on Sunday 6th of May 2018 05:39:43 PM