Will a lower angle mean the efficiency will last longer?

[tekno_boy]

I am about to start my first solar project. My own roof.

It goes like this. I live in Spain and get a LOT of sun. The sun travels directly over my roof from one side to the other. It is just a Tin roof with spray on insulation and I was simply going to cover the roof in new roofing (call "sandwich" here because it is insulation sandwiched between two tin layers with roofing tile effect one side).

Then I thought, why not cover my entire roof in Solar panels, it's only marginally more expensive!

The House is 13m x 7m and the angle of the roof is very slight (about 15 degrees).

I know increasing the angle of the panels will increase efficiency, but I'm not too bothered because I will be installing 91m2 of solar (I will do the whole roof for aesthetic reasons).

Given the solar panels are more efficient at a certain angle (depending on season), Here is my question:

Does generating more power because of an optimal angle speed up the loss of efficiency cased by aging?
Put another way: If a lower angle produces a little less power, will it also reduce in efficiency slower from aging?

Basically, I live in a windy area and my roof is quite flat at only about 15 degrees. I would rater not angle the panels and I want to know if that means because they are less efficient, they will in fact less efficiency slower? Like I say, with that much coverage in Spain I am not worried about getting the most power as I will have definitely way more than I need. So I only need know if I lay the sown right on top of the roof, will their efficiency loss over time be reduced because they are at a flatter angle?

It's a very interesting question and one I have not seen anywhere, hence coming here.

Thanks in advance for any insight you might have!

 

[sunshine_eggo]

Given the solar panels are more efficient at a certain angle (depending on season), Here is my question:

They are not more efficient. They receive more energy.

Does generating more power because of an optimal angle speed up the loss of efficiency cased by aging?
Put another way: If a lower angle produces a little less power, will it also reduce in efficiency slower from aging?

Logically, yes, but I've never seen data to support it.

Basically, I live in a windy area and my roof is quite flat at only about 15 degrees. I would rater not angle the panels and I want to know if that means because they are less efficient, they will in fact less efficiency slower? Like I say, with that much coverage in Spain I am not worried about getting the most power as I will have definitely way more than I need. So I only need know if I lay the sown right on top of the roof, will their efficiency loss over time be reduced because they are at a flatter angle?

At only 15° tilt, your panels will have higher performance (near perfect insolation) in summer where it's hotter, and there will be more thermal "stress".

The reality is likely that the measurable change in life due to tilt is negligible.

Using Madrid as a source (https://pvwatts.nrel.gov/pvwatts.php):

A south facing 1kW array at 15° Tilt will produce 1366kWh/year
A south facing 1kW array at 40° tilt will produce 1411kWh/year

That's a 3% difference annually, but you're producing more of that during hotter summer months, so any "life efficency" savings are likely offset by the higher production in hotter weather. 15° and 40° data below:

 

[400bird]

The reality is likely that the measurable change in life due to tilt is negligible.

I just wanted to repeat this. Panels last decades, they are designed to sit in the sun constantly. The slight differences in life due to sun angle are likely within the measurement error.

I feel like there have been an increase in posts about PV panel life from Europe. I realize there is an energy crisis in Europe, but why does that make everyone think their panels are only going to last a few years?

 

[LeoThomson]

I am about to start my first solar project. My own roof.

Cover your roof, the panels are not that expensive and your roof will be shaded. You might find this resource by @FilterGuy useful to get started.

Overview of Over-paneling an MPPT controller

To get to the paper, click on the orange button at the top of the screen. There is a misconception that putting more panels on an MPPT controller than the controller is able to use will damage the controller. However, in almost all cases it is...

diysolarforum.com

 

[tekno_boy]

Thanks for the prompt answers!! Also, I 'm not worried about lifespan actually, I just wanted to know if when a solar panel creates less power because of whatever reason (because it receives less energy as sunshine_ego said) then would that also mean the "damage" to it's lifespan would be in some relative way lessened.

The answer appears to be yes (although negligible). It does help me to choose to simply put the panels directly on the roof and not try and create a complicated frame to change their angle because any reduction in optimization will in some relative way be offset by longevity (however small). That's what I wanted to know.

Although I must admit that, it turns out the angle isn't so bad after all.

So I wasn't worried about them lasting, It is just WAY easier to install them directly on the roof then to angle them and I was looking for something to help me to decide to do it the simpler way

Thank you all for really fast answers! And good ones! Amazing I thank you all whole heartedly!

 

[ianganderton]

How much air gap are you going to have between the panels and the roof?

A decent space for airflow cooling will have a significant effect on the power production which is reduced with heat

Not sure how much heat reduces lifespan of panels

 

[sunshine_eggo]

More important that the roof mounts allow enough rear clearance fo the panels to cool themselves. My neighbor just removed his old array that had been up for 25 years, and there was essentially no clearance between the frames and the roof - or at least not enough to allow airflow behind the panels. His 1500W array struggled to put out 400W when his 2000W ground mount array is putting out ~1800W+ at the same tilt and orientation.

Array has been replaced using a commercial racking system that allows 5" of clearance between the panels and the roof.

Poor picture, but hopefully you get the idea:

 

[tekno_boy]

Thanks, great shout on the gap for cooling. I understand how important cooling is for solar panels.

That's no problem. There is a gabel on either end of the roof and basically I just don't want to extend past the height of that or it will be exposed to wind (which could be a real issue) but being parallel with the roof with a good 150mm clearance (I have about max 300mm) is no prob. Again thanks!