Panel angle formula?

[nicoloks]

Howdy,

Just wondering if anyone knew where I could find a formula or online calculator, etc, to help me calculator potential production losses in my portable panels from their angle relative to the sun?

The panels are meant to be perpendicular to the sun, but how do I calculate potential loss if I put my panels out for the day and go for a walk and they end up being 35° off.

 

[12VoltInstalls]

I run my panels vertical to eliminate the issue with snow accumulations to clean off.

I typed ‘solar angle calculator’ in my searchbar and this was the top return: http://www.solarelectricityhandbook.com/solar-angle-calculator.html
This is the second one: https://solarsena.com/solar-panel-tilt-angle-calculator/

 

[nicoloks]

Thanks for that. Didn't so much want an optimal angle calculator, more a way of discerning what the production fall off is the further off that optimal angle you get.

 

[pollenface]

I use an Android app called "Optimal Tilt"

Optimal Tilt Angle - PV System - Apps on Google Play

Find your optimal tilt angle for any desired location. Get maximum electricity.

play.google.com

It uses your GPS location and allows you to place your phone on the panels when setting things up to act as an inclometer.

 

[12VoltInstalls]

It’s not linear because it’s per-square-inch of exposure based.
So there’s not a constant.

Calc one 90* arrangement, and then calc you 35* off, subtract the two for a difference. There you have it.

 

[Mike 134]

Use ptwatts. It's geared for permanently mounted solar panels but will give you an idea for your camping setup. Plugin different angles to see the effect.

PVWatts

Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations

pvwatts.nrel.gov

 

[Zwy]

Howdy,

Just wondering if anyone knew where I could find a formula or online calculator, etc, to help me calculator potential production losses in my portable panels from their angle relative to the sun?

The panels are meant to be perpendicular to the sun, but how do I calculate potential loss if I put my panels out for the day and go for a walk and they end up being 35° off.

Usually your latitude is the same angle for a fixed panel angle. You can use a calculator, but really you could go out now as we just passed the spring equinox and use the soup can method with a leveling protractor on the base to get degrees.

If you are looking for tilt that is adjustable, I suggest using this calculator for your location and try various tilt angles for winter/ summer solstice and spring/fall equinox. I found that calculator more accurate than PV Watts.

 

[nycamper62]

This isn't anything 'high tech' - but back when I just used two panels, some superstrut and a dish tv azimuth mount for each one on a pole - all I did was right about 1-2 o'clock I just held a water bottle to each panel and used the tilt to eliminate the shadow.

 

[Warpspeed]

Howdy,

Just wondering if anyone knew where I could find a formula or online calculator, etc, to help me calculator potential production losses in my portable panels from their angle relative to the sun?

The panels are meant to be perpendicular to the sun, but how do I calculate potential loss if I put my panels out for the day and go for a walk and they end up being 35° off.

Its basically what the sun can "see" when its looking at your panel.
If the panel is directly facing the sun its obviously 100% of the area of the panel.
If the sun is completely edge on, its theoretically zero.
Cosine of 0 degrees = 1.0
Cosine of 35 degrees = 0.812
Cosine of 90 degrees = 0
If the sun is off by 35 degrees you will still get about 81% of max.
Even at 45 degrees off, its still about 71%
Its not as critical as many people expect.

 

[Solar Guppy]

where I could find a formula or online calculator, etc, to help me calculator potential production losses in my portable panels from their angle relative to the sun?

It's the Cosine of the difference of panel to sun angle.

Its not as critical as many people expect.

Totally depends on the latitude the panel is at. Since it is not a linear progression those at high latitudes will see a very large difference in output with small angle changes in the Sun.

 

[Warpspeed]

Totally depends on the latitude the panel is at. Since it is not a linear progression those at high latitudes will see a very large difference in output with small angle changes in the Sun.

That is not what he is asking.
He wants to know how much he loses if if the panel is 35 degrees off pointing directly at the sun.

Thirty five degrees of aiming error is thirty five degrees, no matter where you are.
Its a very simple question, and you do not need a sun chart to answer it.

 

[12VoltInstalls]

Even at 45 degrees off, its still about 71%
Its not as critical as many people expect

My panels are vertical year ‘round because in winter I don’t want to be chasing snowflakes with a squeegee to get my measly 4.7 watts of charging. In summer I have so much more solar than needed that I’m charged sufficiently by 9am so I just have them vertical.

I have one array with 400W of panels that face SE. In the afternoons there is no sun on them of course; yet with good sun summer or winter I still see ~150W or more from that array.

Sure, I’m not ‘maximizing production’ whatsoever. But I agree: it’s not as critical as many people expect.
I just accepted the ‘loss’ in winter because I can’t be here all day to clean the snow off angled panels. I see arrays all over the area that are tilted; some stay snow covered for days or even weeks sometimes. This would not work out for me.

 

[Scph9002]

You take a beer bottle and place in on the panel at 12.00. Angle is perfect if you see no shadow.

 

[nycamper62]

You take a beer bottle and place in on the panel at 12.00. Angle is perfect if you see no shadow.

Yup, basically what I said a few posts back, but plastic.

 

[Crowz]

I bought the plastic gadget someone linked off amazon before I used the phone to set the angles with an app.

https://www.amazon.com/gp/product/B0B8J492BR/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[12VoltInstalls]

That’s the same shadow method, just with a cost applied.

 

[xtrorion]

per off grid garage, you will require a 'SPATZ" to calibrate

 

[damo green]

Howdy, Just wondering if anyone knew where I could find a formula or online calculator, etc, to help me calculator potential production losses in my portable panels from their angle relative to the sun? The panels are meant to be perpendicular to the sun, but how do I calculate potential loss if I put my panels out for the day and go for a walk and they end up being 35° off.

Go to pvwatts input different tilt scenarios, compare