I am having my panels moved to a more optimum location. But I get one shot at this so need to get it right.
The reasons for this are:
They are heavily shaded in winter both in the mornings and afternoons from about 14h00 by trees on the East and West
The garage roof where they are now, is leaking heavily and they need to come of for repairs to be done.
Since roughly mid Aug, I have been getting decent production again and peaking currently at about 4500W. Before that I rarely saw 3500W. In proper summer, I peak at 6000W
Currently they are either (mostly) flat, or slightly elevated to face North.
So now they will move to the top of my house roof and all shading will pretty much be gone, which will already be a big improvement in terms of early morning and late afternoon production. I reckon it would be roughly 2-3 extra hours of PV
So have 3 MPPT’s each with roughly 2000W PV capability.
Question now is:
Do I orientate all of them North?
Or do I split the arrays for East, North and West at. I have more than enough space so they wont shade each other.
But once they’re up, it wont be possible to re-orientate them (cost factor - don’t want to spend anymore money on this)
What do I do? Is there historic data that can be looked at to help come to a decision, bearing in mind that I wont be able to interpret the data. I will need someone to help me please.
Generally you want to use up all your north facing roof space first. Once you run out of north facing roof then you start looking at east and west. You want to optimize for winter when the days are shorter and the sun is mostly in the northern sky. East and west only really works well in the summer months.
This website uses historic weather data to estimate future yields:
It spits out montly totals, but you can also download a spreadsheet with estimated yields down to the hour. I suggest you run a simulation with the various orientations and then add up the numbers.
If you want to do:
Maybe the 12 x 410 Watt panel all North and split the 4 x 555 Watts into East and West?
need a bigger MPPT
Maybe skip West or East and do:
150 | 35 with 6 x 410 Watt panels (North)
150 | 45 with 4 x 555 Watt panels (North)
150 | 35 with 6 x 415 Watt panels (East - catch the sunrise)
If you get more cloud in the morning then do N/N/W
If you get more cloud in the afternoon then do N/N/E
I forget where you are located so you have to help with the cloud issue. (Highveld has thunderclouds in the afternoon so WWE is better)
What I am also thinking of now, is that during the summer we have lots of roque clouds drifting everywhere. It may be better to have everything facing North to get all PV thats able to penetrate the cloud cover.
And console myself that at least I wont have shading problems anymore.
You can’t out all 12 on the 150/45 as it’s already maxed.
So without an extra MPPT or an upgrade you have limited choices.
If you are considering an upgrade the a Solis AC inverter maybe a good bet but that is an added complication.
Summer isn’t the issue - daylight hours are plentiful . Maybe see how much more sun you get morning and evening. If you are on a West slope then more West panels is better.
I don’t think it’s difficult but more about a once off and live with it decision.
With 20Kwh of batteries I would go:
150 | 35 with 6 x 410 Watt panels (West)
150 | 35 with 4 x 415 Watt panels (East)
250/100 (tbc) with 10/12 x 555 Watt panels (North) - upgrade the MPPT/and buy 6/8 more panels (cheap at the moment) - sell the 150/45
Then you are done! (TTT will support me… he is trying to work out the “more panels” problem)
You could also swop the 150/45 for a AC inverter connected to the Victron system. Jaco is the man.
I’ve complicated your question badly now, sorry.
No I need to work with what I got. No more additional purchases. Relocating the panels is going to set me back R22k alone.
I suppose with that money I could buy more panels and another MPPT, but they still need to get to the roof. So its a moot point as there is no other space left. That and the fact that there is probably no more space left on the Venus.
I like this, it makes sense. The shading is palatable in summer, but in winter it is downright horrible.
In the new location there will be almost zero shading and I am very happy with the summer production.
So with no shading in winter, it makes sense to keep facing all of them North because I currently manage (barely) provided I get everything done before 14h00
I think I will tell the installer to mount them in such a way that in a very distant future an East and West array is still possible space wise. Then if and when funds allow I could start upgrading to bigger MPPT’s. But that’s not in the foreseeable future at the moment.
In that case I would put those 6 panels (they are close enough in capacity) all in series for a voltage around 300V-ish, and face them all North. Then take the 4 x 555W panels and split them east/west. Yes, I know it is just 1kW each, but I have that exact setup at my place (900W facing east, old Tenesol panels, 1kW pointing west, old 60-cell panels that were a gift from a friend).
The only reason I can think of would be that the North array would do better because I would be able to get the volts up to 300? The buck converter thing?
The voltage isn’t a big deal here. Higher is generally better, but if you already have the cabling pulled in it’s probably not a big deal. The efficiency of a PV-inverter directly to grid is the more important factor for me these days, because I have most of my loads moved to day time. Anyway, I was just saying… if you do look in the direction of a PV-inverter, I would put those 12 panels in one string. They are close enough. Well, I assume their peak current capacity is very close.
At my own house I have 305W and 315W panels in series at the moment (all Canadian Solar, same family of panels).
But yeah, it doesn’t sound like there is a substantial advantage in investing in a PV-inverter.
From my experience the East / West panels did not make THAT much of a difference.
My north facing panels was already throttled by my MPPT, so i figured that i would place any additional panels east and west. I think it was a total of 6 east and 6 west.
The difference was negligible.
Now, this might be due to the angle they were on (around 24degrees), but I did not see the extra 1.5kwh early morning and later in the evening that I expected.
My daily avareage did not change that much (granted it was raining season)
I installed the extra panels in March 20
March - 830kWh
April - 744kWh
May 877kWh
What you don’t see on this image is the daily, I can’t pinpoint the exact day I installed them, so it’s hard for me to find that graph (I’ll keep looking), but I distinctly remember the look on my wife’s face. (That look as if you spent thousands on your garage gadgets)
Just some feedback. Installer only started today due to some complications on another site and the long weekend.
They should finish today with mounting the brackets on the roof and laying the trunking.
Tomorrow will be the horrendous job of moving all panels 3 storeys high. I am very excited/anxious to see how this will change production.
As a rough comparison point, on a clear day currently at 06h20 when the wife leaves for work, the panels produce about 150W. (I hope this at least tripples )
When it is done I will check the graphs for an entire day’s production and compare to pre installation figures.
Installer only managed to relocate 4 panels of the 16 so far. But the difference it made was massive!
Now at 06h20 the panels produce about 170 Watt more bringing me to about 320 Watt and from thereon obviously it climbs much faster than before. I now get just North of 1 Kw by 07h00 in the mornings.
It seems this was a very good move which I should’ve done a long time ago.
Most of the cables and trunking work is done now and all frames are mounted, so hopefully they finish tomorrow.
EDIT: It seems the way things are panning out I may have too much panels and would need to sell some.
Best of all, from the entire roof surface area there is about a 1/3rd left for more panels…
Yes yes. I already scolded myself for saying that. Nice to have the option to add more, but I know now from experience that it would add little value in my current setup.
I’d rather invest in a heat pump by next winter. (Hopefully). Lots of other projects still to complete.
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