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Sticking flexible solar panels


jenevers

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If it is not too late - It is better to NOT use 'stick-down solar panels.

They don't like the heat (from hot tin roofs) and the performance is degraded. Solar is inefficient enough without adding in avoidable reductions in output.

Far better to use 'solid' ones and mount then a couple of inches above the roof to get an air flow under them.

 

As a matter of interest the maximum output of panels is usually on a bright frosty winters day (assuming you have Sun)

 

It may seem counter-intuitive, but solar panel efficiency is affected negatively by temperature increases.  Photovoltaic modules are tested at a temperature of 25 degrees C (STC) – about 77 degrees F., and depending on their installed location, heat can reduce output efficiency by 10-25%.  As the temperature of the solar panel increases, its output current increases exponentially, while the voltage output is reduced linearly. In fact, the voltage reduction is so predictable, that it can be used to accurately measure temperature.  

As a result, heat can severely reduce the solar panel’s production of power. In the built environment, there are a number of ways to deal with this phenomenon.  

 

How to Reduce the Effects of Heat

 

After the module technology is selected for an installation, there are several ways to minimize the negative effects of high temperatures: 

 

• Install panels a few inches above the roof to allow convective air flow to cool the panels down.

• Ensure that panels are constructed with light-coloured materials, to reduce heat absorption.

• Move components like inverters and combiners into the shaded area behind the array.

 

Another source of similar information :

 

https://solarcalculator.com.au/solar-panel-temperature/

 

Edited by Alan de Enfield
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5 minutes ago, jenevers said:

I know, but they are going to be stuck to polycarbonate sheets?

Why would you put contour solar panels on polycarbonate sheets? Attaching a less efficient panel to a base seems counterproductive. 

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16 minutes ago, Cloudinspector said:

My flexible panels are mounted on pot magnets to raise them off the roof. 

They must be hellish powerful!

 

1 hour ago, BWM said:

Why would you put contour solar panels on polycarbonate sheets? Attaching a less efficient panel to a base seems counterproductive. 

What would you attach them to?

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31 minutes ago, jenevers said:

They must be hellish powerful!

 

What would you attach them to?

Yes they are. 

https://e-magnetsuk.com/magnet_products/work_holding_magnets/pot_magnets/external_threaded_stud.aspx

i used 4xE1006 on each panel. We moor on the western L&L where it’s pan flat and wide open and the panels haven’t budged even in the strongest winds. 

Edited by Cloudinspector
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1 hour ago, Cloudinspector said:

My flexible panels are mounted on pot magnets to raise them off the roof. 

I’m thinking of similar as it still gives a lower profile than a solid panel but allows some airflow....what size panels are you using? Do they sag in the middle?? 

 

My other option was magnetic tape in a herringbone pattern to allow water to drain. I thought then you could remove them to allow roof maintenance etc. And they could still be walked on a push....I’m also not a fan of holes in boat roofs!  

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I stick most things with Bondit PU18 and have yet to come across a material that doesn't stick.  The bond can be broken if necessary using a long thin blade like a bread knife.   My flexibles are stuck down to my polycarbonate canopy.   

 

Edited by Murflynn
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1 minute ago, Murflynn said:

I stick most things with Bondit PU18 and have yet to come across a material that doesn't stick.  The bond can be broken if necessary using a long thin blade like a bread knife.   My flexibles are stuck down to my polycarbonate canopy.   

 

Thanks for the info. How long since you stuck the panels down and are they flat or curved?

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3 hours ago, jenevers said:

Thanks for the info. How long since you stuck the panels down and are they flat or curved?

3years, no issues.   

flat, but I can't see it makes any difference.  

even tolerates my little boat being towed at 60mph which is like suffering a full gale for a couple of hours.

each 100W panel is stuck down fully along all edges and once across the middle.

Edited by Murflynn
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Great. Just one thing you should consider, if your panels are stuck down fully along all edges, this can lead to the whole panel bulging on a very hot day as the air under the panel is trapped. I would get a Stanley blade and just create a slit in the adhesive, to allow air to escape. Bulging can crack the cells. See below (page ?

 

https://www.photonicuniverse.com/upload/file/Manuals/EFLX/EFLX-Semi-Flexible-Solar-Panels-Handling-And-Installation-Manual.pdf

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48 minutes ago, jenevers said:

Which particular pot magnets do you use? There’s lots of choice.

 

10 hours ago, Cloudinspector said:

 

https://e-magnetsuk.com/magnet_products/work_holding_magnets/pot_magnets/external_threaded_stud.aspx

i used 4xE1006 on each panel. We moor on the western L&L where it’s pan flat and wide open and the panels haven’t budged even in the strongest winds. 

 

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16 hours ago, Alan de Enfield said:

If it is not too late - It is better to NOT use 'stick-down solar panels.

They don't like the heat (from hot tin roofs) and the performance is degraded. Solar is inefficient enough without adding in avoidable reductions in output.

Far better to use 'solid' ones and mount then a couple of inches above the roof to get an air flow under them.

 

As a matter of interest the maximum output of panels is usually on a bright frosty winters day (assuming you have Sun)

 

It may seem counter-intuitive, but solar panel efficiency is affected negatively by temperature increases.  Photovoltaic modules are tested at a temperature of 25 degrees C (STC) – about 77 degrees F., and depending on their installed location, heat can reduce output efficiency by 10-25%.  As the temperature of the solar panel increases, its output current increases exponentially, while the voltage output is reduced linearly. In fact, the voltage reduction is so predictable, that it can be used to accurately measure temperature.  

As a result, heat can severely reduce the solar panel’s production of power. In the built environment, there are a number of ways to deal with this phenomenon.  

 

How to Reduce the Effects of Heat

 

After the module technology is selected for an installation, there are several ways to minimize the negative effects of high temperatures: 

 

• Install panels a few inches above the roof to allow convective air flow to cool the panels down.

• Ensure that panels are constructed with light-coloured materials, to reduce heat absorption.

• Move components like inverters and combiners into the shaded area behind the array.

 

Another source of similar information :

 

https://solarcalculator.com.au/solar-panel-temperature/

 

Mine worked fine glued down to the light cream roof, the panels used the roof as a heat sink, I used a laser thermometer on them once they were warm and the roof around them was warm but a few inches on the roof was cooler. They are also more easy to live with than rigid panels as ropes dont get caught up in them.

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7 hours ago, peterboat said:

Mine worked fine glued down to the light cream roof, the panels used the roof as a heat sink, I used a laser thermometer on them once, they were warm and the roof around them was warm, but a few inches on the roof was cooler. They are also more easy to live with than rigid panels as ropes dont get caught up in them.

 

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21 hours ago, frangar said:

I’m thinking of similar as it still gives a lower profile than a solid panel but allows some airflow....what size panels are you using? Do they sag in the middle?? 

 

My other option was magnetic tape in a herringbone pattern to allow water to drain. I thought then you could remove them to allow roof maintenance etc. And they could still be walked on a push....I’m also not a fan of holes in boat roofs!  

They did sag a little especially when it had rained. I remedied this using a length of beading underneath the centre. 

I’ve ordered some adhesive magnetic strips to use as a permanent solution.

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