So whats the most optimal (best average) angle for panels in South africa ?

G

"Textbook wisdom" is your latitude plus 15 degrees adjustment for winter and minus 15 for summer. So in SA, from Musina at 22deg South to Cape Town at 34 deg South, a tilt angle somewhere around 25 or 30 degrees as a fixed average round number, directed at true north? But this makes more sense if you are using all the available power as it gets generated, or have enough storage or can exchange with the grid.

It also would depend on the typical weather in different seasons, highveld winter gives pretty good production compared to spring and autumn when it is more cloudy and hazy. I would imagine winter in Cape Town gives pretty poor production. 

@The Bulldog posted this great resource in another thread recently.

Here is a simpler solar angle calculator.

I have one array pointing NE at the moment, but think my angle is too shallow.

My north array is not bad, it has a nice shallow angle which means mid day I have a good 90deg angle to the rays,

Thinking to expand my north array, but thinking I'll lower the angle a bit so that it has a better impact, earlier.

Depending on this angle... it might be a separate Charge Controller if the difference is not to wide between the current north facing array and this additional 3 or 6 panels (for additional 6 I will have to replace the MPPT anyhow so would rathe make sense to keep separate).

G

3 hours ago, georgelza said:

My north array is not bad, it has a nice shallow angle which means mid day I have a good 90deg angle to the rays,

? At this time of the year, the sun is considerably north of overhead. For me, it's getting close to 40° north of directly overhead [ edit: at noon ].

So a shallow angle (to the horizontal ground) is bad for this time of year. What am I missing here?

Edit 2: perhaps you are trying to optimise for summer? I have too much solar power in summer, and not in winter, so I prefer to optimise for winter. I have 6 panels at 45° to the horizontal for that reason. My latitude is 27.5°.

Edited May 16, 20197 yr by Coulomb

@georgelza  Download ScanTheSun onto an android phone.

Nice to play with, easy to use and lots of interesting variations. Oh, and free...

goops, no Androids in this house gold...

G

Just now, georgelza said:

goops, no Androids in this house gold...

G

I have one as my iPhone gave me notice.

They are cheap and I was pleasantly surprised with their quality.

Hi @georgelza

iPhone Apps has an App called Sun Seeker.

You search your location an it will show you the angles at the time you select (Hour, day month, etc)

It is actually breathtaking to see how much you loose due to angle.

awesome, thanks, will give it a try, was planning on jumping onto the roof with phone, have a app called measurements which also gives me the exact angle. which is a good start to know.

G

Umm, ok, so I'm confused again.

I have seen both the calculators posted above before, and have made some notes to try and optimize my setup once I am able to get to the buy and install point. Anyways, I was under the impression that my roof at 26* tilt, and approx 5* azimuth was quite good for an all-round setup. However, I've just played a bit with the "JRC" calculator a bit more just out of interest, and used the "optimize slope" calculation on the site. Apparently 1* tilt is the best according to the calculator?

Calc1 is the one off the solarhandbook's page, calc2 is the calculated 1* tilt, calc3 is using the same angle as recommended as per solarhandbook's page's result.

@Minerva10210 I have played around with the JRC calculator quite a bit too, and to be honest I think it may contain a few bugs, especially when re-calculating after changing values.

If I open the site fresh, and input the details for optimal slope and azi at your location, then I get (very) different results:

That is more what I would expect given your location.

8 minutes ago, IdlePhaedrus said:

@Minerva10210 I have played around with the JRC calculator quite a bit too, and to be honest I think it may contain a few bugs, especially when re-calculating after changing values.

If I open the site fresh, and input the details for optimal slope and azi at your location, then I get (very) different results:

That is more what I would expect given your location.

Hold on, I think I may have the Azimuth angle in wrong there, I was assuming North as 0*, and I now see they seem to be basing their calcs by default to be Northern Hemisphere - so my input might be out by 180*

 

Yes, correct, some calculators work with 0 as north and others at -180.

I have been looking at another calculator and asked them about this, and they said it really depends if the software was written in the northern or southern hemisphere.

It is quite interesting too if you want to take a look: https://solcast.com/

You have to create an account, but it is free.

Edited May 29, 20197 yr by IdlePhaedrus
spelling

I tested my current setup and angles with both the calculators and it currently give me the same output that I see on my side. 

Last few days the output is down because of cloud coverage and haziness. 

4 minutes ago, Luminous said:

I tested my current setup and angles with both the calculators and it currently give me the same output that I see on my side. 

Last few days the output is down because of cloud coverage and haziness. 

The solcast calculator is supposed to take hourly satellite information into account and give a fairly accurate measurement for the last few days given cloud cover, and an estimate for the next few days.

I am not sure how up to date the satellite data is for our part of the world, but it is an interesting concept.

Edited May 29, 20197 yr by IdlePhaedrus
grammar

On 2019/05/16 at 5:44 AM, georgelza said:

So whats the most optimal (best average) angle for panels in South africa ?

G

Hi @georgelza

I had the "average" setup for a year and now have moved to another strategy totally.

I tilt for the best winter yield (NE facing @ around 30-35deg) and accept that in summer I'll get less.  Days are longer in summer anyway and so things balance out.

I used to change between winter and summer but find this works well for me.  I should change 4x a year but lazy I am

Today (hazy day) I got 80% of max yield and yesterday (clear and cold) 95%.

Edited May 30, 20197 yr by Mark

1 hour ago, Mark said:

I tilt for the best winter yield (NE facing @ around 30-35deg) and accept that in summer I'll get less

I think this is a good strategy, and I think I might do it in future as my production far outstrips my usage in summer.

problem is i doubt i can change my tilt without allot of rework and cost.

G

While searching for a specific website I can't find it happens to be the one with results posted by

@Minerva10210

I have tried many forecasting sites and my conclusion is that my weather APP that gives the hours of sunlight per day and just adjusting this figure to my historic yield turns out much more accurate than any forecasting site. Some taking into account the current weather are at times over 35% out and gives figures higher than I have achieved on any specific day in 4 yrs. 

My system is working at full tilt and not affected by load or battery state. 

On 2019/05/16 at 8:22 AM, DeepBass9 said:

I would imagine winter in Cape Town gives pretty poor production.

My system performs quite well for my home needs even in winter.
Panel strings are split 4 facing east and 6 facing west each on its own mppt and both strings are at about 40 degrees.
Surprisingly I get quite good production in winter too. My batteries are still full around midday. I had one week where we did not see the sun for 5 days yet the batteries still charged up nicely. The cloudy weather in cape town tends to still have quite good iradience and the good diffusion of that iradience.

Here is an awesome resource I use for solar

Put in your co-ordinates and you will get everything you need for your solar install with regards to panels in relation to your roof space, angles etc.
On the left menu is a solar specific box where you can get angles and expected iradience levels
You can zoom right down to street level and even see where shadows will affect you at different times of the day.

https://www.suncalc.org/#/40.1789,-3.5156,3/2023.03.21/13:56/1/3

Edited March 21, 20233 yr by WannabeSolarSparky

4 hours ago, WannabeSolarSparky said:

Here is an awesome resource I use for solar

Put in your co-ordinates and you will get everything you need for your solar install with regards to panels in relation to your roof space, angles etc.
On the left menu is a solar specific box where you can get angles and expected iradience levels
You can zoom right down to street level and even see where shadows will affect you at different times of the day.

https://www.suncalc.org/#/40.1789,-3.5156,3/2023.03.21/13:56/1/3

Thanks for the link. 

Does anybody know what the addy is for the forecast 

@Minerva10210 used on 29 May in this Fred?

Part of the result. 

9 minutes ago, Scorp007 said:

Thanks for the link. 

Does anybody know what the addy is for the forecast 

@Minerva10210 used on 29 May in this Fred?

Part of the result. 

You looking for this?
http://www.solarelectricityhandbook.com/solar-angle-calculator.html