Solar panel angle

oldbloke · Guru

Solar panel angle

Whenarewethere · Guru

Just sketch on the back of an envelope any angle you want, divide the angled width of the parallel lines by the width of the overhead sun, then multiply by watts.

Or on your smartphone calculator: Panel Watts sin angle = Watts you will get.

Screenshot_20220612-201429~2.png

Jaahn · Guru

Hi oldbloke smile

Thanks for the kind comment. The theory says the output does fall as the panels get hot. My experience years ago camping with a couple of panels, is that flat on the ground they do get very hot. In full sun in summer you can hardly put your hand on them. At my house the solar output is best on a clear sunny day with a light breeze which keeps the panels cool. aww

If you fit panels to a caravan roof then it has always been recommended to leave a 50mm gap to allow cooling air to circulate under them. So glueing flexible panels direct to the roof is not so good. They might not suffer as much as glass panels though. But some people have had poor experiences with flexible panels which can have a short life, even thought they are more expensive. hmm

Here is some information on the loss of output VS temperature of the panel. https://www.solar.com/learn/does-solar-panel-temperature-coefficient-matter/

"Most solar panels have a temperature coefficient of around -0.3% / °C to -0.5% / °C. For example, SunPowers solar panels all have a temperature coefficient of -0.37% / °C.

What this means is that for every 1°C above 25°C, SunPowers solar panels decrease in efficiency by 0.37%. So, if your panels are at 35°C (95°F) and have an overall efficiency of 17%, then their true efficiency at that temperature will be closer to 16.4%."

I do believe that caravans with flat panels on the roof do struggle to get enough power down south. Made worse by trees and other shade factors like camping down near the river and similar nice places. Extra portable panels with long cables are one answer to that. Most just use gennies. Mike has talked about his answers. This year has been bad with the lack of sun also. disbelief

Jaahn

-- Edited by Jaahn on Monday 13th of June 2022 08:12:27 AM

swamp · Senior Member

hi
Having a camper with MPPT and a combo of 200w fixed /roof and 200w portable totalling 400watts works for most of my situations . Wired in parallel to allow for shade . Large cabling . Using 1 or 2 agm 120ah .
Following the sun is not a problem .

Remember the PSH [peak sun hours ] in southern states can halve in colder months therefore you need at least double the size of wattage required in Vic or Tazzy .

So angle the panels or have xtra panels whatever floats your boat . I Vote for xtra wattage

-- Edited by swamp on Wednesday 6th of July 2022 08:28:41 AM

TimTim · Guru

I have never tested any of my solar my solar panels in relation to the sun angle except for being flat and directly facing the sun. Interestingly i came across this video of Will Prowses in which he testes solar panels at different angles. The results show very little difference in output between 10 and 40 degrees and in looking at the figures I would say very little difference between 0 and 40 degrees.

-- Edited by TimTim on Saturday 30th of July 2022 01:47:41 AM

Mike Harding · Guru

Then I suggest there's something wrong with his experiment.

Not only does my experience show a difference but if you adjust angles in this calculator you'll also see one:

Solar calculator

jegog · Senior Member

Mike Harding wrote:
Then I suggest there's something wrong with his experiment.
Not only does my experience show a difference but if you adjust angles in this calculator you'll also see one:
Solar calculator

As Sol was Fong of saying "Oils ain't oils".

A lot depends on the panel being used and it's mounting.

Screen Shot 2022-07-30 at 10.43.16 am.png

Dick0 · Guru

TimTim wrote:
I have never tested any of my solar my solar panels in relation to the sun angle except for being flat and directly facing the sun. Interestingly i came across this video of Will Prowses in which he testes solar panels at different angles. The results show very little difference in output between 10 and 40 degrees and in looking at the figures I would say very little difference between 0 and 40 degrees.

-- Edited by TimTim on Saturday 30th of July 2022 01:47:41 AM

Too much over thinking these days about solar panel angles for caravans.

With the new light weight panels available today just install more capacity and you will no longer need to worry about angles. Set and forget especially with Lithium batteries.

Additionally, you will create a cooler van with much of the roof covered.

Works for me. smile smile smile

Mike Harding · Guru

I will speculate the incidence of bifacial solar panels used by the camping and nomad community is of the order of 0.0000001%

https://www.semprius.com/bifacial-solar-panels/

Mike Harding · Guru

Dick0 wrote:
Too much over thinking these days about solar panel angles for caravans.
With the new light weight panels available today just install more capacity and you will no longer need to worry about angles. Set and forget especially with Lithium batteries.

You recently posted that you were camped near Longreach, Qld. In July in Longreach 800W of flat panel will produce 85kWh of energy.

I am near Stawell, Vic. In July in Stawell 800W of flat panel will produce 41kWh of energy.

However, if I set my panels at 65d and move them a few times during the day they will produce 81kWh of energy.

Statement of the ilk "Just buy more panels" are nieave, simplistic and fail to understand all the issues associated with solar harvesting in a mobile situation.

Dick0 · Guru

Mike Harding wrote:
I will speculate the incidence of bifacial solar panels used by the camping and nomad community is of the order of 0.0000001%
https://www.semprius.com/bifacial-solar-panels/

And you would be correct.

Also, they are heavier so why would they be used, especially for caravans and portable applications.

confuse confuse confuse

Dick0 · Guru

Mike Harding wrote:
Dick0 wrote:
Too much over thinking these days about solar panel angles for caravans.
With the new light weight panels available today just install more capacity and you will no longer need to worry about angles. Set and forget especially with Lithium batteries.
You recently posted that you were camped near Longreach, Qld. In July in Longreach 800W of flat panel will produce 85kWh of energy.
I am near Stawell, Vic. In July in Stawell 800W of flat panel will produce 41kWh of energy.
However, if I set my panels at 65d and move them a few times during the day they will produce 81kWh of energy.
Statement of the ilk "Just buy more panels" are nieave, simplistic and fail to understand all the issues associated with solar harvesting in a mobile situation.

Travelling to FNQ I had five days straight of wet and inclement weather, however, my batteries took on full charge by mere Daylight.

I stress again, I post here what works for me and do not, as you, offend and belittle others because you disagree with them.

Also, I do not tell others what they should or should not do, rather, suggest and recommend what works for me.

So, to you, everyone with whom you disagree is naïve, simplistic and lacks understanding.

Again, I stress what works for me...and it does work for me.

Mike Harding · Guru

Dick0 wrote:
I stress again, I post here what works for me and do not, as you, offend and belittle others because you disagree with them.

You make assertive posts regarding a technical subject of which you have little knowledge. You look at a very narrow focus (ie. yours) associated with gathering solar energy and you assume your approach will suit everyone else - it won't! Then you get all grumpy when someone with good knowledge and qualifications contradicts you. I have spent a working life-time at the front edge of electronics and I *do* have some idea what I'm talking about. If I am wrong then come back to me with the facts and mathematics of *why* I am wrong and I'll change my position and be grateful to you for correcting me. That's engineering for you, it's not about pride.

This is a major issue with internet forums and it's usually why knowledgeable people (eg. Collyn Rivers) stop posting; we get fed up with people making definitive technical statement when they are really just presenting confirmation bias.

I may be an arrogant pr!ck but, electronically, I'm usually a correct arrogant pr!ck.

jegog · Senior Member

Mike Harding suggested that there was something wrong with another's testing methodology when it returned a result that he did not expect - all, I suspect, without watching the utube video.
Had he watched the video he might not have made that comment.
My post in reply was to point out that there are many different types of solar cells with vastly different characteristics.
As for his comment re the usage of that type of panel by the grey nomad community, well I was not suggesting that the shown panels should be mounted on caravans, and as I just said, I was pointing out that there are many different types of solar cells.
However there may be readers who have a home, and having it pointed out that not all solar cells are the same might just be beneficial.

Dick0 · Guru

Mike Harding wrote:
Dick0 wrote:
I stress again, I post here what works for me and do not, as you, offend and belittle others because you disagree with them.
You make assertive posts regarding a technical subject of which you have little knowledge. You look at a very narrow focus (ie. yours) associated with gathering solar energy and you assume your approach will suit everyone else - it won't! Then you get all grumpy when someone with good knowledge and qualifications contradicts you. I have spent a working life-time at the front edge of electronics and I *do* have some idea what I'm talking about. If I am wrong then come back to me with the facts and mathematics of *why* I am wrong and I'll change my position and be grateful to you for correcting me. That's engineering for you, it's not about pride.
This is a major issue with internet forums and it's usually why knowledgeable people (eg. Collyn Rivers) stop posting; we get fed up with people making definitive technical statement when they are really just presenting confirmation bias.
I may be an arrogant pr!ck but, electronically, I'm usually a correct arrogant pr!ck.

My goodness, you even call yourself an arrogant pr!ck.

Mike Harding · Guru

Dick0 wrote:
My goodness, you even call yourself an arrogant pr!ck.

Sure: arrogance is one of my personality failings.

How about you Dick0, what are your personality flaws? Or do you not have any?

Dick0 · Guru

Mike Harding wrote:
Dick0 wrote:
My goodness, you even call yourself an arrogant pr!ck.
Sure: arrogance is one of my personality failings.
How about you Dick0, what are your personality flaws? Or do you not have any?

Time for you to take a Chill Pill and stop being personally abusive.

Mike Harding · Guru

Thanks Dick0, you have answered my question.

TimTim · Guru

There was nothing wrong with his simplistic test but depending on your location and panels you have you cant expect to have similar results.

https://www.youtube.com/watch?v=c-auRHKq2-A

Cassie63 · Senior Member

I know my solar works as the beers are cold