here is a pic of my place. I dont want to use the roof with black lines (street facing).  The roof with red lines is 70% taken by pool and geyser solar

cannot ascertain from the pic, but can you fit 12 times 540 watt panels on your roof, it will give you 6480 watts, 6 panels on each string.

Looks like you would have a great East/West split, I would put 5 panels where the red lines are facing East and then the other 5 on the West facing part of the roof

I would just get the installer to install some extra rails for more panels if you decide to slot a few extra's in later. Will make your life a lot easier later and won't cost too much to do.  

thanks, is an E/W split better than all north? 

Slightly less max power +-10% I think depending on the angles, you can calculate it, there are websites. 

But much better power in the morning and in the afternoon. East/West is a winner IMO.

I get good power starting at 7:00 and finishing at around 6:30 at the moment.

Doesn't look like you have much North facing roof space in any case. 

Would get up there with a tape measure and measure how much space you have so you can plan your layout.

 

Agree with @Sc00bsregarding east/west layout, and also about laying out the rails one time for future expansion

7 hours ago, Tariq said:

@Vaal, what panels are you planning on using

Hi Tariq. I bought ten JA 535w Mono Perc half cell MBB panels. I've got a bit of usable roof space problem. The 1 Noth facing roof is 12m long. My house is built in the form of a H with the long sides looking north south.  The short part is a flat roof and currently occupied by a solar geyser which might give me some shading problems in the winter. 

Edited January 5, 20224 yr by Vaal

So if you put all ten panels on the 12 meter North roof (they should fit ), are you saying that the end panels will be shaded?

The roof I have that is west facing has loads of space. 

The roof that is east facing doesn't have too much space, can I use east + north on one string then the other string just west? 

6 minutes ago, Terminal3k said:

The roof that is east facing doesn't have too much space, can I use east + north on one string then the other string just west? 

Just my 2 cents worth put 4 North facing, 3 West Facing and 3 East facing, connect 2 north facing with 3 east and the other 2 north facing with west coz it's what i did and works perfect

Edited January 5, 20224 yr by Quwatush Shams (Suly)

13 hours ago, Quwatush Shams (Suly) said:

Just my 2 cents worth put 4 North facing, 3 West Facing and 3 East facing, connect 2 north facing with 3 east and the other 2 north facing with west coz it's what i did and works perfect

He only has two MPPT controllers, what you are suggesting may actually be the worst way of doing it.

Whilst you may still get some power from the panels, the amount you get will always be limited by the panels generating the least amount of power in the string.

How you have suggested connecting the panels makes no sense whatsoever.   

22 hours ago, Terminal3k said:

here is a pic of my place. I dont want to use the roof with black lines (street facing).  The roof with red lines is 70% taken by pool and geyser solar

I would consider moving your pool panels to the North facing roof near the chimney if there is enough space and using the East facing roof for solar panels. 

8 minutes ago, Sc00bs said:

I would consider moving your pool panels to the North facing roof near the chimney if there is enough space and using the East facing roof for solar panels. 

Thank you. I will try move them to make space for the panels. There should be space for the pool panels next to the chimney. 

I didn't realise the panels are limited by the on getting the least power 

32 minutes ago, Sc00bs said:

He only has two MPPT controllers, what you are suggesting may actually be the worst way of doing it.

Whilst you may still get some power from the panels, the amount you get will always be limited by the panels generating the least amount of power in the string.

How you have suggested connecting the panels makes no sense whatsoever.   

 

 

@Quwatush Shams (Suly), has an 8 kW Sunsynk, which can accodate two strings in parallel on one mppt, so it can work. I had a Victron with one mppt, with two strings in parallel facing NE and NW, did make much of a difference in production.

unfortunately the 5 kW is not the same

Edited January 6, 20224 yr by Tariq

21 minutes ago, Tariq said:

@Quwatush Shams (Suly), has an 8 kW Sunsynk, which can accodate two strings in parallel on one mppt, so it can work. I had a Victron with one mppt, with two strings in parallel facing NE and NW, did make much of a difference in production.

unfortunately the 5 kW is not the same

@Tariq  Hmmm, so my understanding is that it is impossible for an single MPPT to work optimally if it is connected to panels which are facing different directions.

The reason for this is that the IV Curves are different for each roof area because they get a different amount of irradiance from each string of panels. This means there are 2 maximum power points to choose from and an MPPT can only optimise properly to 1 maximum. 

 

It will work, just probably the worst way you can connect them up. It will result in the MPPT optimising for the lowest voltage panels and a loss of power conversion from the panels with the better solar irradiance. Just like how having a one of your panels in the shade brings the whole strings power down

 

@Terminal3k  A good video from Sunsynk explaining the MPPT and overwatting on the panels. 

 

17 hours ago, Vaal said:

Hi Tariq. I bought ten JA 535w Mono Perc half cell MBB panels. I've got a bit of usable roof space problem. The 1 Noth facing roof is 12m long. My house is built in the form of a H with the long sides looking north south.  The short part is a flat roof and currently occupied by a solar geyser which might give me some shading problems in the winter. 

Google maps photo of your roof maybe? 

 

1 hour ago, Tariq said:

@Quwatush Shams (Suly), has an 8 kW Sunsynk, which can accodate two strings in parallel on one mppt, so it can work. I had a Victron with one mppt, with two strings in parallel facing NE and NW, did make much of a difference in production.

unfortunately the 5 kW is not the same

How do you know what the power loss was @Tariq

I would think that the actual loss of power would have to do with the difference in the voltages between the strings, with the MPPT always picking to optimise on the string with the lower voltage.

If @Quwatush Shams (Suly) connected them up in parallel there would be more loss as the number of panels in the strings facing different directions are all different

"4 North facing, 3 West Facing and 3 East facing, connect 2 north facing with 3 east and the other 2 north facing" 

If they are connected up in series, you are only going to get whatever the lowest amperage is of any one of the panels in the string. So if your North facing Panel wants to produce 12A but your East can only make 6A then that whole string will only produce 6Amps. Basically what happens when you have shade on one of your panels pulling the whole strings production down.   

 

My guess would be that if you absolutely have to connect panels facing different directions to one MPPT, probably the best way to do it would be to have panels of equal lengths facing different directions in parallel. If I look at my panels, the voltages are usually pretty stable at their max apart from a short time at the start and end of the day.

I assume that the MPPT would optimise on the lowest strings voltage which if they are the same length would be very similar for most of the day.

The only thing I am not sure of it how the MPPT would handle different amperage coming from different directions for example

 North String 4 panels producing 12A@310V

East String 4 panels producing 7A @ 300V

Both strings are wired in parallel to one MPPT

MPPT will optimise for 300V

300V*12A=3600W vs 310V*12A = 3720W - is only a slight loss as long as the voltage are similar

Not 100% sure what happens to the Amps, maybe someone else smarter than me can comment.  I assume that it would be the addition of the Amps form the two strings:

North facing 12A + East Facing 7A = 19A @ 300V = 5700W

But could be the lowest Amperage value of the two strings 

North Facing 12A + East Facing 7A = 7A x2 = 14A @ 300V = 4200W

2 hours ago, Terminal3k said:

I didn't realise the panels are limited by the on getting the least power 

Yup, that is why you want to avoid shade on any one of the panels as it will pull the amperage of the whole string down. 

You will also get better heating on the north facing roof for your pool. 

Do you have enough roof space on your East/West roof to put two rows of panels on the roof?

 

Panels vary in size, 455W are about 2.1 x 1.05  and then just get them to install rails 4200mm rails instead of 3405mm rails so you can add an extra two on later

Really depends on the size of your roof though, I think you could mount them in landscape if necessary

 

Here is a picture of my east roof.

The roof in red blocks some early morning sun (black). I have not measured the space out yet.

there is more than enough space on the west roof

Edited January 6, 20224 yr by Terminal3k

@Terminal3k, what are the dimensions of this roof, i.e length X breadth 

2 hours ago, Sc00bs said:

How do you know what the power loss was @Tariq

i was getting up to a 83% of the 4.2 kWp on a nice stable sunny day, granted, with 2 mppt's on the Sunsynk, i am hitting 90% and more sometimes

38 minutes ago, Tariq said:

i was getting up to a 83% of the 4.2 kWp on a nice stable sunny day, granted, with 2 mppt's on the Sunsynk, i am hitting 90% and more sometimes

Hope this diagram makes sense to you. Is there space to put panels under the pool solar?

The JaSolar 535-540 watt panels are 2279mm, would you be able to fit them under the geyser panels, or push the geyser panels up a bit.

2 hours ago, Tariq said:

The JaSolar 535-540 watt panels are 2279mm, would you be able to fit them under the geyser panels, or push the geyser panels up a bit.

I don't think those are black geyser panels @Tariq, they are just for the pool. 

I would move them to below the other 3 on the right of the geyser if possible and then just put two rows of panels to the left of the geyser.

You will need +4.5mtr from the gutter to the peak of the roof to fit on comfortably.  

You have 17 rows of tiles @ 335mm per row (I think that is standard) = 6,03 mtr

So you should have enough space to put in two rows of 2.1mtr panels.

4 x 4.2mtr rails on roof hooks would give you space for 4 panels across by two panels high

 

20 minutes ago, Sc00bs said:

I don't think those are black geyser panels @Tariq, they are just for the pool. 

I would move them to below the other 3 on the right of the geyser if possible and then just put two rows of panels to the left of the geyser.

Unfortunately there isn't enough space for the pool panels underneath /on top of each other on the right. Is my other option to move them to north roof? 

What about landscape under the pool? 

Edited January 6, 20224 yr by Terminal3k