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Feedback required - tilting panels at the perfect angle.


SilverNodashi
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Hi guys, 

I want to open this discussion for anyone who has done some experiment in this regard. Is it really worth-it to make sure panels are tilt at the perfect angle? The main reason I'm asking is that it's actually impossible for small scale installations to do this right, at an affordable rate. Solar tracker is super expensive and if you calculate the economics of scale, I wonder if it's really worth-it in terms of monitory value.

Let me explain this from some experience. My neighbor built a solar tracker to accomodate 9x 250w solar panels which cost a small fortune. It tracks the sun quite well and most possibly allowed about 1-2 hours extra energy harvesting during the day at full capacity. One day I noticed it's not working anymore and I asked him about it, he said it's too dangerous with the strong winds we sometimes get to use it all the time. Fair point. Later on he added 6x more panels on his roof and said it was cheaper to get the extra energy this way than to use the solar tracker. The brackets on his roof if adjustable but he never really adjusted them. 
My roof is a pitched roof, probably at 30 degrees ( I never checked) so I cannot change the angle, nor the pitch of the panels without mounting my panels onto a separate structure 

http://www.solarpaneltilt.com/ says " Panels that track the movement of the sun throughout the day can receive 10% (in winter) to 40% (in summer) more energy than fixed panels".

So if I have a 1Kw (let's use round numbers for ease of example) system that would yield 1100W in winter, and 1400W in summer. So, my 4x 250W PV which cost R10,000 (R10/w) could yield another 40% in summer with an expensive tracker, possibly in the region of R5k for a 1KW tracker. And you need a structure that can work with the solar tracker. My pitch roof won't work, so I'll have to spend another say R3000 for a stand, planted in the garden somewhere to handle something like this. 40% is 400w in this case. 2x 250w additional panels will give me 500W extra energy @ R5000 + some extra cables, let's say another R800. 

On a 10Kw system the match would be more of less the same, although I guess then you would have paid R9/w for PV. The structure you mount your panels to would probably scale linearly in terms of cost. 

Please note, I'm not trying to start a price war here. Prices are purely estimated to prove a point. 

 

What to discuss:

Has anyone installed & used a solar tracker, and possibly compared it with a stationary system of the same size, and actually got 40% more energy out of it in summer? My guss is it would be more in the region of 20%, perhaps 30% gain. 

i.e. take 2x 1KW system (or whatever size you want, bigger systems will show the yield difference better, I guess) - one on a solar tracker and one stationary and compary the energy harvested during the day to see if it really makes that much difference. Ideally both installations need to be in close proximity to each other, be connected to the same brand + model MPPT and battery bank. 

 

To further this discussion, and why I'm starting it is this: Is it really necessary, on a north facing roof, to have a 30 degree angle, for example. Or, how much harvesting capacity would one loose if the panels were flat on a carport roof, for example. I think generally carports are sloped at 4 degrees?

Solar panel mounting structures are expensive, with good cause. But to illustrate another point: To add an angular mounting structure cost about R800 extra, per panel, using an N-1 formula. So on the same 1Kw array you would use 5x angular mounts of sort - that say R4000 extra! Again, at that price I could just as well add 2x 250w panels to the same PV array and have more energy at my disposal. 

 

Right now I don't have a spare set of panels, MPPT controller, batteries and either a flat mounting structure, or one to mount some tracker on todo this research myself, but hopefully someone else had done this already? Or know of some research in this regard that could shed some useful numbers and feedback on the subject?

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Hi

I have fixed panels and used http://www.pveducation.org/pvcdrom/properties-of-sunlight/solar-radiation-on-tilted-surface to calculate my angle and biased it to a winter focus which has less hours than summer.  They are fixed and would rather add more panels for west and east bias than a tracker...  wind worries me with a tracker...

large.56eee80198d3b_PanelTilt.JPG.e2f834

Regards

Mark

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Only if you have a grid tied inverter or a very big bank do you have to worry about that in my opinion as you only then need max output. I do not have loads on my system the whole day. So I just move the load to run when we do have the power to do it. My panels are at 26 degrees fixed. 

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I have fixed panels as well on a 35deg pitch roof. They are split into two banks each from their own MPPT, one facing East North East - supplying sun in summer from 6am till around 2pm, the second bank is North North West facing - supplying the pv's from around 11am till up to 7 or 8pm. I would also rather ad more panels to both banks than put up tracking systems, the cheapest i have seen that can handle 12 pv's start at around R37k.....and thats dealer price

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  • 2 weeks later...

Build your own.  The dude who installed my panels built his own. It is mounted on top of his roof. It controls 18 panels. 

Johan's tracker works ike the Sedona tracker

I built a scale model of the tracker I wanted to build but then I discovered I need grid tied or else the tracker will be a waste of time.  So if I go grid tied then the tracker will move back to the list of projects to complete. 

 

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  • 1 month later...
On 4/10/2016 at 11:38 AM, jdp said:

Build your own.  The dude who installed my panels built his own. It is mounted on top of his roof. It controls 18 panels. 

Johan's tracker works ike the Sedona tracker

I built a scale model of the tracker I wanted to build but then I discovered I need grid tied or else the tracker will be a waste of time.  So if I go grid tied then the tracker will move back to the list of projects to complete. 

 

Have a look at the shading at around 3 minutes 50 seconds on the video. Is it worth it?

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@SilverNodashi While researching my own installation I came across some research that was done in SA on the topic (see link below). In there you should find some comparison between the efficiency of fix and tracking installations at various locations in South Africa. There has been other studies since that expand on it but I found this one interesting.  Instead of building a test rig, they used weather and environmental data collected and ran it through simulation software to estimate the optimal angles (Azimuth & Tilt) for various locations in SA in terms of Highest Yearly Energy production and Highest Daily Energy production. They calculated it for fixed system and various tracking systems (see table 4).

For example, I have a fixed panel grid tied system in Pretoria. if I want the maximum yearly energy production I would have to point the panels 10o East at an angle of 30o

This was not what I expected. I always thought that pointing the panels due north would be best. It turns out this is not always true (depending on where you live). In Pretoria we normally get rain in the afternoon during summer. The data showed that afternoons are more cloudy then the mornings. So pointing the panels slightly to the east turns out to be a better option in the long run.

http://www.erc.uct.ac.za/sites/default/files/image_tool/images/119/jesa/18-2jesa-bekker.pdf

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Yes it is. Here is Johan's system, mine will be similar. You get shading anyway at some stage during the day in a static system as well.

 

 

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21 minutes ago, jdp said:

About R40K for 18 panels.

I like that tracker!!! A LOT!!!

BUT ... What would could it cost to mount 18 panels? Lets say it is wot, +-R10k?

He said you effectively get 1 panel free for every 3 you have. A  panel is wot -R3k.

He has 18 panels so that gives me as much as 6 more panels - so +-R18k for 6 more panels. Now I have 24 panels.

So if I do it normally, optimally mounted, no tracker:
Installation +-R10k
More panels: +-R18

For +-R28k I get the same amount of power? No worries about wind or moving parts?

BUT, I have 3 panels ... I dropped them a email. :D For if is true that you get 1 more panel for every 3 with a MPPT controller ... living in CPT where winter and summer has a huge difference on the suns movement over the panels - depending on the price off course. :P

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4 hours ago, jdp said:

If you have the space add the panels. My roof is not that big so I add a tracker to get more power from less panels.

Do you have dimensions of this frame, I see a huge space lost between the panels making up mounting space for extra panels if it's not used

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talking about the space lost and the cost of the tracker vs just adding more panels to your existing install to make up the power lost.

The only true thing the tracker probably brings to the table is longer hours of sun, but then again is it worth the cost?

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8 hours ago, jdp said:

Well he has the stats to prove it.

Based on what? It would be nice if they published actual figures and test results. It would also be nice if they could compare that system to a stationary setup with the same panels, on the same roof, going into similar MPPT trackers, but his roof is too small and the outlay is probably too much. 

There's 10x Polycrystal and 8x Monocrystal panels on that rack

So, let's assume the following:
1. The poly's are 72cells, so let's asume it's 300W (Yingli?) panels, or 3000w in total. 
2. The mono's are also 72cells, but I can't find those panels on the web, so let's assume it's 250w, total of 2000W. 
3. The normal calculation for good sun hours is 6 hours, so 5000W at 6 hours should produce round about 30Kw. 
4. South Africa has on average 9 hours sunlight per day. 
5. Lastly, lets assume the ventilation is good enough (should be in this case) that the panels perform 100%

So, if they were stationary, we should have gotten 30Kw for the day. But since they're moving and getting 3 hours extra sunlight, they should produce 45Kw. That's 33% increase, and maybe it's even possible. It just sounds too optimistic to me. You will probably find that the sun is high enough between 8am and 16:00 to hit all the panels on that tracker, otherwise the panels at the back would be shaded by the front panels. 

 

So, who wants to build a tracker (let's forget about SABS and TUV approval which will increase the production cost significantly) and compare it with a stationary setup? 2Kw PV array per setup, going into similar MPPT trackers and central battery bank + central inverter so there's constant draw / usage on the system. 

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I am with Silver on this one. Want to see apples for apples.

And here and there I have noticed minor shade of the frame falling on some of or most panels. That is mos an issue, not?

 

There was a solar tracker dealer in George. One day I contacted him and asked for a quote, for I really would like to get more bang for my buck.

His response: We have stopped importing and selling them because of a)) Costs and b)) it is cheaper to add 1-3 more panels, depending on your setup.

So the jury has ruled on this one. Solar trackers loses versus fixed mount with couple extra panels, ito cost. And it complicates the installation for there are now moving parts.

BUT if you have space constraints or shade complications, then a solar tracker may probably be your only answer.

Must say, that monstrosity on my roof, not today. I would LOVE to do what Chris did, op die grond, maklik en naby om te kan beloer.

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