Advice Needed - Panel Layout

Good Day Everybody

I am looking into putting up some panels in the “near” future.
The goal is to fit roughly 3000W in panels on the roof.
I have some shading to deal with, that will affect panel choice and layout.

What I have concidered this far is (6x510W) or (5x590W) to achieve my goal.
Im adding some photos, hoping for some advice on panel choice and layout based on the shading.

Thanks in Advance.

Photos are from July, I have less shade to deal with in summer.
Roof faces NE

8AM

9AM

11AM

1PM

3PM

Something to remember is that PV panels are sold as a peak power rate, but that is not what you normally get. All panels are like that.

As an example lets look at the ArtSolar 550W panel


The STC values is that wattage it is sold under and is measures in perfect factory conditions. It is used so you can compare vs the next panel and most manufacturers will use very similar test conditions, but this could be a bit different. Check the specs.

The NOCT is more the normal power you can expect every day use when the PV is mounted in the sun, hot and hopefully not to dusty.

So what to do with this information?
For safety calculations (wire thinkness, fuses, breakers, max voltage limits) you should use the STC values.
For usage requirements (how much panels you need to power your system) you should use the NOCT values.

I also have lost of shade in the winter that is out of my control. So I looked at half cell panels (144 half cells) and instead of using one bit MPPT with one or perhaps 2 trackers I went with smaller MPPT charge controllers each with their own tracker. Victron’s modular system makes this easy to do, but if you are looking at another system where the charge controllers are built into the inverter you might not have that opion.

your 11am and 1pm are going to be your big solar power times so I would put as many panels as you can fit in that bright spot.

I’d just chop down the palm trees. :grin:

and thats why the karoo is perfect :laughing:

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My palm tree doesnt bug me much, the ones that are making the shade are 2 houses down and extremely tall

What system/brand are you planning to use?
Do you also have east/west facing roof and how is the sun looking on them?

Currently I have a kodak axpert mk2,
From another setup I helped a friend with I know the mppt likes to be at higher voltages.
Hence trying to get a single string of 5 to 6 panels as a start.
The idea would be to double that in the following year.
I am looking at Canadian Solar Panels at the moment.

House only has NE and SW facing roof space.
I would need to confirm what that side is like, i know there is shade in the morning, would need to do similar photos to see pattern throughout the day.

Focused on this side as I’m trying to get as close to north facing as I can

East and west facing panels worksvery well, but south will not work. You will have to use the north roof.
With the Axpert you will not be as flexable in your approach as I could be and for a high voltage string with 5-6 panels you will want them all in the sun. Any shade will limit the whole string. So see if you can optimise their placement as much as you can.


I think this is your least shaded area around midday

I think higher up on the roof is best. As the days get longer some of those shadows will fall off the roof (sort of speak). You will be better off with 1/2 cut cell as half the panel can be in shade and you will still get the other half worth of energy and a single string will perform better than if full cells. Better still one MPPT per panel however I suspect you will already be aware of this.

Sometimes optimising for winter is not the best for the whole year performance. I have east north and west facing panels. Due to a tall building immediately to my north my north roof is mostly in shade during the depths of winter. I place only four panels on my north facing roof in order to minimise the shade on the north panels. However if I had of placed more panels on the north facing roof they would more than make up for the winter losses in the six months that include summer. My north panels usually produce about 20-30% more than either east or west facing panels.

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