Hi

 

Just looking at different options. If I get an 8Kw inverter, I have 3 orientations I can put the panels. The issue is I have is the North direction can only fit 4 panels. The East and West can take about 8 panels. What I wanted to ask is could I put 8 545w panels facing East on to string1 of MPPT1, then at a later date put a few panels on the West side and connect these to string2 MPPT1. Then Connect the 4 panels on the North side to String 1 on MPPT2.

 

If this will work, then do you wire the 8 panels East in series ( have checked it will be 398v VOC and 13.93 A ISC) , then connect the panels facing west in series? Then how do you connect them to Pv1-1 and PV1-2 do they have to go through a combiner box as I see it only has 4 inputs under the inverter. Then do you put the North facing 4 panels through a separate combiner box as well even though there is only 1 string

 

P.S. Can the strings East and West be different sizes so 8 panels East and maybe 5 Panels west (Same panel wattages 545w)

Edited July 14, 20233 yr by Greglsh

East and west each onto their own mppt. Not a good idea to mix different directions on same mppt.
General rule - each direction on to it's own mppt to achieve max power efficiency.
If you have awkward roof space configurations and run out of mppt ports on the main inverter then you can always use/add a few smaller mppt controllers and link all to the battery banks with bus bars.

1 hour ago, Greglsh said:

The East and West can take about 8 panels.

If both east and west can take 8 panels each then you can do each 8 in series and each one into a separate mppt port on the inverter.

@Greglsh

I would not even consider having east and west into the same MPPT if the one side has 5 panels and the other side 8.

What do other members think? 

Edited July 14, 20233 yr by Scorp007

1 hour ago, Scorp007 said:

@Greglsh

I would not even consider having east and west into the same MPPT if the one side has 5 panels and the other side 8.

What do other members think? 

@GreglshDefinetly east/west not on the same MPPT. For now 4 Panels North Mppt 1 and 4 panels East on Mppt 2. Later you can add another 4 east and put 8 panels West on seperate Mppt like @WannabeSolarSparkysuggested.

 

Edited July 14, 20233 yr by TaliaB

Some useful info that i got from Sengen website irradiance for some major towns. The table below gives examples of energy generation for each kWp of PV panels installed.

Location	kWh/kWp
Bloemfontein	2055
Cape Town	1762
Durban	1570
Johannesburg/Pretoria	1871
Nelspruit	1766
Port Elizabeth	1698
Upington	2075

Not sure why you are being told here that you can't have East and west on 1 mppt. You certainly can but you must use the same amount of panels in each orientation and the panel specs must be the same. 

You then parallel each orientation in the inverter. The inverter has 2 string inputs on each mppt so there is no need to combine them in a separate box. You will however need a PV DB for breakers/fuses and surge protection. 

100% @Chris_SI'm in your bus of thought. I have been doing this for some time now to great effect!

Must be the same panels & same number. If not the same then abort the idea💡

Edited July 15, 20233 yr by Steve87

Another topic about using east and west on the same MPPT. 

Sometimes we have to try configurations even if we think it will not work well and measure the results. 

 

Edited July 15, 20233 yr by Scorp007

5 hours ago, Chris_S said:

Not sure why you are being told here that you can't have East and west on 1 mppt. You certainly can but you must use the same amount of panels in each orientation and the panel specs must be the same. 

You then parallel each orientation in the inverter. The inverter has 2 string inputs on each mppt so there is no need to combine them in a separate box. You will however need a PV DB for breakers/fuses and surge protection. 

That is what I was thinking but was not 100% sure. Also when you say "Parallel each orientation in the inverter" Where is this done, sorry if stupid question. Does each string have to go through it's own PV DB or do you put the East and West through the same PV DB?

 

16 hours ago, TaliaB said:

@GreglshDefinetly east/west not on the same MPPT. For now 4 Panels North Mppt 1 and 4 panels East on Mppt 2. Later you can add another 4 east and put 8 panels West on seperate Mppt like @WannabeSolarSparkysuggested.

Thanks for the info TaliaB

 

Would this not require 3 MPPT's 1 for North, 1 for East and 1 for West? Are you saying move the 4 North to East or West?

 

4 hours ago, Greglsh said:

Are you saying move the 4 North to East or West?

No not at all if you can fit panels North then that is a win. What is the exact roof direction east and west? You can connect 4 north in series with 4 east on 1 Mppt if your east roof is facing NE and then do 8s for the west side on Mppt 2. It also depends when you need the most production in the mornings or afternoon. Below is the direction of an east roof that can be series connected with north facing panels. I did an installation 5 North 5 East connected in series on 1 Mppt and the results where good but the client needed more production in the morning and batteries was charged earlier.

 

Edited July 15, 20233 yr by TaliaB

Okay, so I am limited to 4 panels North as that is all the roof space I have facing north as per my very bad image. Would the size of the panels have to be the same, so if I only have space for 4 North could I put say 545w panels. The 8 panels East would be +_ 450w ( i have 4 already), then later add maybe 6 panels West of 545w

9 hours ago, Greglsh said:

That is what I was thinking but was not 100% sure. Also when you say "Parallel each orientation in the inverter" Where is this done, sorry if stupid question. Does each string have to go through it's own PV DB or do you put the East and West through the same PV DB?

The inverter will combine the 2 series strings. You can use 1 DB for the 2 strings but each string has its own breaker and own surge protector. Basically it's a 2 in 2 out DB. You will see it labeled on the inverter PB2-1 and PV2-2

If using only 4 panels per string make sure your panels are around 50 Voc each. The mppt needs 150V to start. 

48 minutes ago, Greglsh said:

Okay, so I am limited to 4 panels North as that is all the roof space I have facing north as per my very bad image. Would the size of the panels have to be the same, so if I only have space for 4 North could I put say 545w panels. The 8 panels East would be +_ 450w ( i have 4 already), then later add maybe 6 panels West of 545w

North facing is always your best direction. Looks like you need careful measurements of your space so you can get creative. See if you can get 6 panels facing north even if you mix portrait and landscape. 

Then also see if you can do 5 East and 5 west. 

55 minutes ago, Greglsh said:

Okay, so I am limited to 4 panels North as that is all the roof space I have facing north as per my very bad image. Would the size of the panels have to be the same, so if I only have space for 4 North could I put say 545w panels. The 8 panels East would be +_ 450w ( i have 4 already), then later add maybe 6 panels West of 545w

If you prefer wiring solar panels of different ratings,it is a better idea to separate the panels in two sets and wire them in parallel. With a solar array comprising different solar panels, the only way to avoid losses of the installed wattage is separating the panels in individual circuits. BUT keep in mind different solar panels reduce the effectiveness of the controller to track this optimal power point. 

What do you think of this layout maybe? The extra one near the chimney could be an issue with shadows from the small wall next to it and from the chimney. I need to get up and measure this space exactly. This is just an idea. Maybe make it 5 panels on the East side as well. Could I connect the North panels (either 5 or 6) and the East panels either 5 or 6 to 1 MPPT and not cause issues?

 

Edited July 15, 20233 yr by Greglsh

4 hours ago, Greglsh said:

What do you think of this layout maybe? The extra one near the chimney could be an issue with shadows from the small wall next to it and from the chimney. I need to get up and measure this space exactly. This is just an idea. Maybe make it 5 panels on the East side as well. Could I connect the North panels (either 5 or 6) and the East panels either 5 or 6 to 1 MPPT and not cause issues?

 

I think you need to be more precise with your panel orientations. Maybe give them in degrees. What you've been calling North and West, are actually closer to NW and SW, and this can have a material impact on the power your panels generate.

You might be better off placing 6 panels facing NW on MPPT1, and then 6+6 in parallel on the NE roof, which seems to have the space, especially if going for the 450W panels instead of the 545W panel (lower Imp).

The caveat: You haven't mentioned anything in this discussion of the power demand for this household, or of the battery storage planned, or the time of day that loads will be run. The layout I'm suggesting I think would work best if you've got bigger loads or batteries to recharge in the morning, and want to run a geyser from mid-day.

10 hours ago, Greglsh said:

What do you think of this layout maybe? The extra one near the chimney could be an issue with shadows from the small wall next to it and from the chimney. I need to get up and measure this space exactly. This is just an idea. Maybe make it 5 panels on the East side as well. Could I connect the North panels (either 5 or 6) and the East panels either 5 or 6 to 1 MPPT and not cause issues?

 

I would just ensure your panels are the same size as per the sketch. It makes it easier while you work out how to connect. 

Stick to suggestion of @Steve87 with respect to different numbers of panels on east and west if used on 1 MPPT.

The 6th panel on the north string in series with the other 5 will affect the whole string in the afternoon. Just check from what time you have shade from the chimney. 

Quote

On 2023/07/16 at 4:10 AM, GreenFields said:

The caveat: You haven't mentioned anything in this discussion of the power demand for this household, or of the battery storage planned, or the time of day that loads will be run. The layout I'm suggesting I think would work best if you've got bigger loads or batteries to recharge in the morning, and want to run a geyser from mid-day.

Hi GreenFields (Sorry long story)

So What I want to do is to build the system slowly. I currently have a 1000w inverter that keeps my internet and a few small item running during load shedding. I already have 1x 1.2kw and 1x 1.5 kw micro inverters running to lower the electricity bill. I also have a granny flat and double garage, this currently uses about R1300 per month electricity. The house currently uses about R800 a month due to the micro inverters generating about +- 300Kwh per month over the last 6 months.

So here is the longer term plan

1) Install an 8kw inverter (no batteries to start, I know this will turn off when no power, grid tied)

2) Use my existing 4 x 450w panels on the East facing roof and add another 2 x450w panels. Then add 6 x 450w panels to the West facing roof.

3) Take my 4 x 330w panels from the 1.2kw micro inverter and install them on the North facing roof as they are smaller than the 450w, connect these to the 1500w micro inverter and either wire them directly into the DB like they are now, or connect them to the AUX port of the inverter(not sure which one will give me better generation).

Hopefully this should cover most of the daytime loads for both the house and the granny flat. I do have an old spinning meter but I know you are not supposed to back feed.

5) Start by getting 1 x 5Kwh 1c lithium battery just to cover some basics during load shedding then adding a battery or 2 to be able to use less and less of Eskom

 

Edited July 17, 20233 yr by Greglsh

13 minutes ago, Greglsh said:

Hi GreenFields (Sorry long story)

So What I want to do is to build the system slowly. I currently have a 1000w inverter that keeps my internet and a few small item running during load shedding. I already have 1x 1.2kw and 1x 1.5 kw micro inverters running to lower the electricity bill. I also have a granny flat and double garage, this currently uses about R1300 per month electricity. The house currently uses about R800 a month due to the micro inverters generating about +- 300Kwh per month over the last 6 months.

So here is the longer term plan

1) Install an 8kw inverter (no batteries to start, I know this will turn off when no power, grid tied)

2) Use my existing 4 x 450w panels on the East facing roof and add another 2 x450w panels. Then add 6 x 450w panels to the West facing roof.

3) Take my 4 x 330w panels from the 1.2kw micro inverter and install them on the North facing roof as they are smaller than the 450w, connect these to the 1500w micro inverter and either wire them directly into the DB like they are now, or connect them to the AUX port of the inverter (not sure which one will give me better generation).

Hopefully this should cover most of the daytime loads for both the house and the granny flat. I do have an old spinning meter but I know you are not supposed to back feed.

5) Start by getting 1 x 5Kwh 1c lithium battery just to cover some basics during load shedding then adding a battery or 2 to be able to use less and less of Eskom

Hi Gregish

Don't mind the long story, more info gives a clearer picture.

Here's my 2c worth of responses to your points. I'd suggest discussing it with your installer, maybe one of the other sharp minds that have given you inputs so far, maybe @Steve87 or @TaliaB to comment. I make full allowance for the possibility that I'm talking nonsense.

1). Noted, you're starting your 8kW Deye grid-tied at first, with a view to expanding with more panels and batteries later.

2).  My personal view: Do NOT place panels on your West Roof. It is actually not facing West. It is in fact facing South-West. You will be wasting the capability of your panels, around 20%-25% drop in potential output, especially poorer in Winter. Your best chance for maximising your power is to focus on the other side of the house that faces to the sun (Look at the way your shadows fall). I think it's fine to first put 6 panels on MPPT1 on the North-East side (and it's not East, it's actually North-East). But then when you add panels later, I'd suggest to add even more panels on the North-East side. On the same MPPT1, say 6 of the same panels in parallel. But do it at the same time as you are starting to add batteries, and then forget about the South-West side. If later on you will not be adding batteries at the same time as panels, rather put 6 more panels on the North-West side on MPPT2, on the elevated section of roof.

3). If you are placing 4x330W panels on the micro-inverter, on the North-West side (not North-side, it's North-West), then I actually think that's your best chance to make maximum use of the North-West roof in the vicinity of the chimney, on the lower level. Since your risk of shading is highest there, it would help to keep it on the separate MPPT of the micro-inverter, and rather consider using the micro-inverter input on the generator/AUX-input of the Deye inverter, for a power boost. Assuming the micro-inverter control is compatible with your grid-tie inverter. Use the export limitation function on the Deye inverter to prevent export to the grid.

4) This will give you a decent amount of daytime power for your household loads, up to around 7kW of peak power when accounting for the panel orientation. But you will only really be able to make good use of that amount of panels when you're starting to add batteries, maybe 10-20kWh of battery capacity at least, otherwise your panels are likely to be idle most of the day. It doesn't make sense to forge ahead with panels while lagging with adding storage. Even just after connecting the 3x330W on micro-inverter and 6x450W on MPPT1, you should be adding batteries first before considering more panels.

5). I'd suggest starting out with a 1.5C battery if you can, if you're only taking one 5kWh battery in the beginning.

@GreenFieldsyou always make valuable comments. 

2 hours ago, GreenFields said:

: Do NOT place panels on your West Roof.

That is the reason to do proper orientation of your roof direction. Use your smartphone if it has a magnetic sensor download compass software. @Greglsh to give you an example generally, a solar panel system with a single-axis solar tracker will deliver a performance gain of 25 to 35 percent.

2 hours ago, GreenFields said:

If you are placing 4x330W panels on the micro-inverter

Microinverters are definitely a value-add, but are only recommended if you have panels facing multiple orientations or you have shading issues. Otherwise, the less-expensive standard inverter is usually more cost-effective.

2 hours ago, GreenFields said:

I'd suggest starting out with a 1.5C battery if you can

Yes definetly Greenrich 5000 series either wall mount or rack they can deliver 140 amp discharge true 1.5C. 

My motto as much panels facing North in series that can accommodate your Mppt higher voltage less copper losses, more efficient. North/East good call but dependant on load requirements period (am or pm).  If required N/W  ensure it is actually N/W and not S/W.

10 minutes ago, TaliaB said:

Microinverters are definitely a value-add, but are only recommended if you have panels facing multiple orientations or you have shading issues. Otherwise, the less-expensive standard inverter is usually more cost-effective.

In the latest post above, the OP has got micro-inverters already in use. That was not stated in the original post. I'm suggesting that the best place to apply them is for panels placed on the lower NW roof section, since they can operate independently from the MPPT of the main inverter, and help overcome the shading risks of the chimney.

6 minutes ago, GreenFields said:

In the latest post above, the OP has got micro-inverters already in use. That was not stated in the original post. I'm suggesting that the best place to apply them is for panels placed on the lower NW roof section, since they can operate independently from the MPPT of the main inverter, and help overcome the shading risks of the chimney.

@GreenFieldsSorry yes then it makes sense. Had hectic few weeks, busy with endless problems on Medical suite install. Will post on Showcase when done.

3 hours ago, GreenFields said:

Gregish

Don't mind the long story, more info gives a clearer picture.

Here's my 2c worth of responses to your points. I'd suggest discussing it with your installer, maybe one of the other sharp minds that have given you inputs so far, maybe @Steve87 or @TaliaB to comment. I make full allowance for the possibility that I'm talking nonsense.

1). Noted, you're starting your 8kW Deye grid-tied at first, with a view to expanding with more panels and batteries later.

2).  My personal view: Do NOT place panels on your West Roof. It is actually not facing West. It is in fact facing South-West. You will be wasting the capability of your panels, around 20%-25% drop in potential output, especially poorer in Winter. Your best chance for maximising your power is to focus on the other side of the house that faces to the sun (Look at the way your shadows fall). I think it's fine to first put 6 panels on MPPT1 on the North-East side (and it's not East, it's actually North-East). But then when you add panels later, I'd suggest to add even more panels on the North-East side. On the same MPPT1, say 6 of the same panels in parallel. But do it at the same time as you are starting to add batteries, and then forget about the South-West side. If later on you will not be adding batteries at the same time as panels, rather put 6 more panels on the North-West side on MPPT2, on the elevated section of roof.

3). If you are placing 4x330W panels on the micro-inverter, on the North-West side (not North-side, it's North-West), then I actually think that's your best chance to make maximum use of the North-West roof in the vicinity of the chimney, on the lower level. Since your risk of shading is highest there, it would help to keep it on the separate MPPT of the micro-inverter, and rather consider using the micro-inverter input on the generator/AUX-input of the Deye inverter, for a power boost. Assuming the micro-inverter control is compatible with your grid-tie inverter. Use the export limitation function on the Deye inverter to prevent export to the grid.

4) This will give you a decent amount of daytime power for your household loads, up to around 7kW of peak power when accounting for the panel orientation. But you will only really be able to make good use of that amount of panels when you're starting to add batteries, maybe 10-20kWh of battery capacity at least, otherwise your panels are likely to be idle most of the day. It doesn't make sense to forge ahead with panels while lagging with adding storage. Even just after connecting the 3x330W on micro-inverter and 6x450W on MPPT1, you should be adding batteries first before considering more panels.

5). I'd suggest starting out with a 1.5C battery if you can, if you're only taking one 5kWh battery in the beginning.

Awesome post with some good pointers here. The SW is a very poor place to seat panels.