I'm in the design phase of a new house and want to run mostly off solar. I currently have a 8kw inverter and 7.5kw battery with a 3.9kw array so I understand some basics.

 

New property is in the WC and unfortunately due to the erf layout the roof will be east west. I also have a roof limit of 9 pannels per side because of HOA rules on having to have dormer windows.

I'm considering a 16kw Deye or Sunsync inverter with 15-30kw batteries. I'm trying to figure out what are the largest pannels I can use. I see many adverts saying the Deye/Sunsync has a limit of 8 x 550w pannels per mppt with 3 mppt's. This means I would be limited to 8 a side. 

Any insight into the max pannel capacity and or other options would be greatly appreciated. 

 

Thanks in advance

6 hours ago, BarendD said:

I'm in the design phase of a new house and want to run mostly off solar. I currently have a 8kw inverter and 7.5kw battery with a 3.9kw array so I understand some basics.

 

New property is in the WC and unfortunately due to the erf layout the roof will be east west. I also have a roof limit of 9 pannels per side because of HOA rules on having to have dormer windows.

I'm considering a 16kw Deye or Sunsync inverter with 15-30kw batteries. I'm trying to figure out what are the largest pannels I can use. I see many adverts saying the Deye/Sunsync has a limit of 8 x 550w pannels per mppt with 3 mppt's. This means I would be limited to 8 a side. 

Any insight into the max pannel capacity and or other options would be greatly appreciated. 

 

Thanks in advance

Note that battery energy is measured in kWh. You probably want to be able to run your inverter for two hours at full power rating as a rule of thumb for sizing your battery.

That being said. You could oversize the inverter and solar to sell back to the municipality.

Sunsynk inverters limit their MPPT current if the Imp of the panels exceed the MPPT rating. However, you don't want to exceed 500V Voc on a cold day.

Apologies. Looks like the 16kW inverter only does 450V solar input. The 3 phase 12kW unit does 1000V and allows you to run 3 phase equipment.

3 hours ago, frivan said:

Apologies. Looks like the 16kW inverter only does 450V solar input. The 3 phase 12kW unit does 1000V and allows you to run 3 phase equipment.

Thank you. This is where i get confused. 450V is calculated on pannels running in series, I think. 48.5 x 9 is getting awful close the that 450v and I'm guessing thats why they say 8 pannels max. Can one just install 650w pannels if they still 48.5v as in my mind that's 800w more input per mppt?

Edited March 14, 20242 yr by BarendD

19 minutes ago, BarendD said:

Thank you. This is where i get confused. 450V is calculated on pannels running in series, I think. 48.5 x 9 is getting awful close the that 450v and I'm guessing thats why they say 8 pannels max. Can one just install 650w pannels if they still 48.5v as in my mind that's 800w more input per mppt?

Maybe look at these 605W panels with Voc of 41.5V. If you can physically fit 9 of them per side, the Voltage fits comfortably in the MPPT range.

https://powerforum-store.co.za/collections/solar-panels/products/canadian-solar-605w-super-high-power-mono-perc-hiku7-with-evo2

I don't think the 550W panels are best suited to this inverter. You wouldn't be able to make best use of the PV input capabilities. Pmax at 13A just doesn't work out well here.

3 hours ago, BarendD said:

Thank you. This is where i get confused. 450V is calculated on pannels running in series, I think. 48.5 x 9 is getting awful close the that 450v and I'm guessing thats why they say 8 pannels max. Can one just install 650w pannels if they still 48.5v as in my mind that's 800w more input per mppt?

Since there are 3 MPPT's on the 16kW Deye inverter, you could have 6 X 550W panels E and W each on their own MPPT and then 3 + 3 E and W panels adding up to 6S on the 3d MPPT input, that's what I would do, if I had your limitations...

At which elevation angle are the east and west roofs? fairly flat or quite steep?

The specification indicates a design value of 370V DC as the target value (per MPPT) that can safely fluctuate up to 425V with maximum input  as 500V. I would stay in the 370 to 420V range, keeping in mind the input current of 26A and the maximimum power of 20.8 Kw. 

5 hours ago, Kalahari Meerkat said:

Since there are 3 MPPT's on the 16kW Deye inverter, you could have 6 X 550W panels E and W each on their own MPPT and then 3 + 3 E and W panels adding up to 6S on the 3d MPPT input, that's what I would do, if I had your limitations...

At which elevation angle are the east and west roofs? fairly flat or quite steep?

The 2 strings of 6 each direction I agree. As far as the last 6 in series with 3 each E and W I am standing on the side line. Reason is I guess the output would be low due to throttling of either side except during midday? 

I might lean towards putting each 3 into a micro inverter and use the Aux port as an input? 

5 hours ago, CobusK said:

The specification indicates a design value of 370V DC as the target value (per MPPT) that can safely fluctuate up to 425V with maximum input  as 500V. I would stay in the 370 to 420V range, keeping in mind the input current of 26A and the maximimum power of 20.8 Kw. 

Here I'm back to wondering which inverter model is being spoken of. If it's this model SUN-16K-SG01LP1-EU, then 9x550W panels with 49V Voc, that could possibly actually work in this OP's use case. Otherwise folks could parallel two strings of the 550W panels on each MPPT to max out the capacity or get close. That's 6S2P per MPPT to end up with 19800W.

But if it's the 16kW Sunsynk Max as per the Herholdt's website, with 450V max PV, and 18kW PV limit, then the solution could look different. Here 10 x the 600W 41.5Voc panel with 17.45A per MPPT looks like it works out nicely to 18000W. Else one could look around for 11A panels to string in parallel, but that just seems too much.

Adding micro-inverters or else using the third MPPT with a East/West strings in series or parallel string just seems a bit unnecessary. I'd just keep the 3rd MPPT open as a spare. Or hook up a wind turbine to piss off the HOA. Just my 2c.

 

https://herholdts.co.za/pi58793/sunsynk-16kw-1p-hybrid-pv-inverter-48v-c-w-wifi-dongle-ip65/

Edited March 14, 20242 yr by GreenFields

1 hour ago, GreenFields said:

Here I'm back to wondering which inverter model is being spoken of. If it's this model SUN-16K-SG01LP1-EU, then 9x550W panels with 49V Voc, that could possibly actually work in this OP's use case.

Yes, it is the Deye 16K. Herewith the data sheet p41 of the manual: 

On 2024/03/14 at 9:50 AM, Kalahari Meerkat said:

Since there are 3 MPPT's on the 16kW Deye inverter, you could have 6 X 550W panels E and W each on their own MPPT and then 3 + 3 E and W panels adding up to 6S on the 3d MPPT input, that's what I would do, if I had your limitations...

At which elevation angle are the east and west roofs? fairly flat or quite steep?

Unfortunately due to building regulations roofs have to be between 30 and 40°, my angle is 32. Roof is facing 80/250. 

 

With a 3/3 split how early will it reach min voltage? I don't want to loose production due to low voltage especially in winter. 

 

13 minutes ago, BarendD said:

With a 3/3 split how early will it reach min voltage? I don't want to loose production due to low voltage especially in winter. 

Daylight provides Voltage, but only direct illumination will provide Current, so from probably mid-morning until mid-afternoon that 3+3 string will provide power and not too much early morning and later afternoon, I'd guess, even though the Voltage should be there...

4 hours ago, Kalahari Meerkat said:

Daylight provides Voltage, but only direct illumination will provide Current, so from probably mid-morning until mid-afternoon that 3+3 string will provide power and not too much early morning and later afternoon, I'd guess, even though the Voltage should be there...

Thank you. These are the finer details I don't know. Also didn't realise that not all pannels are the same voltage. I thought they would all be +-48v. 

Thank you everyone for your responses. I've learned quite a lot on here already. I did forget about a carport that I can add pannels on. Learning on here about different pannels has different volts and dimensions it had come to me that I can infact fit 6 x 425w or 5 x 550w pannels on my carport. They will fill up the entire space but they will fit. Once again not sure which will be the better option. Guessing high voltage to get above startup volts. This will the take my 3rd mppt. 

Can anyone explain to me what the following means and where to use it

Voc 

Vmp

Isc

Imp

 

Finally would calculationg all of this really help or the day you get an installer will they just look at me like I'm a idiot and then they do what they feel is best?

 

 

50 minutes ago, BarendD said:

Finally would calculationg all of this really help or the day you get an installer will they just look at me like I'm a idiot and then they do what they feel is best?

I don't think it's bad to start thinking about your system now but be open to listening to your installer as well. With the benefit of a site visit he should be able to add insights that are not said or seen by the forumites. You're on the right track with thinking to add the carport onto the 3rd MPPT. On the other hand, maybe the 250 degree panels facing slightly South-West could be iffy.

Voc - Open circuit Voltage

Vmp - Voltage at maximum power point

Isc - Short-circuit current

Imp - Current at maximum power.

Basically, check these specs on the panel's datasheet, and make sure that in your panel configuration you keep within the limits of the inverter's input requirements. If you search the forum there are probably more than a few discussions on this, but you could also ask your installer to check and confirm.

On 2024/03/14 at 7:07 PM, GreenFields said:

Here I'm back to wondering which inverter model is being spoken of. If it's this model SUN-16K-SG01LP1-EU, then 9x550W panels with 49V Voc, that could possibly actually work in this OP's use case. Otherwise folks could parallel two strings of the 550W panels on each MPPT to max out the capacity or get close. That's 6S2P per MPPT to end up with 19800W.

But if it's the 16kW Sunsynk Max as per the Herholdt's website, with 450V max PV, and 18kW PV limit, then the solution could look different. Here 10 x the 600W 41.5Voc panel with 17.45A per MPPT looks like it works out nicely to 18000W. Else one could look around for 11A panels to string in parallel, but that just seems too much.

Adding micro-inverters or else using the third MPPT with a East/West strings in series or parallel string just seems a bit unnecessary. I'd just keep the 3rd MPPT open as a spare. Or hook up a wind turbine to piss off the HOA. Just my 2c.

 

https://herholdts.co.za/pi58793/sunsynk-16kw-1p-hybrid-pv-inverter-48v-c-w-wifi-dongle-ip65/

I've been looking some more at roof layout. I've finally settled on 8 pannels per side and 5 on the car park. Could you please assist me with start up voltage vs mppt voltage. If I run 5 x 550w pannels @ 48v that will give me 240v, this is below the mppt voltage but above the startup voltage. Will it still work or not? Below is the pannels in considering

TIA

 

https://powerforum-store.co.za/collections/solar-panels/products/seraphim-siv-monocrystalline-series-550wp-silver-frame

Edited April 8, 20242 yr by BarendD

21 hours ago, BarendD said:

I've been looking some more at roof layout. I've finally settled on 8 pannels per side and 5 on the car park. Could you please assist me with start up voltage vs mppt voltage. If I run 5 x 550w pannels @ 48v that will give me 240v, this is below the mppt voltage but above the startup voltage. Will it still work or not? Below is the pannels in considering

TIA

 

https://powerforum-store.co.za/collections/solar-panels/products/seraphim-siv-monocrystalline-series-550wp-silver-frame

AFAIK the MPPT range is where it is most effecient. My personal experience has been that the efficiency is the same even when operating at the lower value. 50V in my case. There is the school that propose to get to the middle of the MPPT range. This operating voltage is then the Vmp as per specs on the panels. 

@BarendD Bottom line is, it will work well enough. But the panels will not operate at 5x48Voc, it will mainly operate at around 5xVmp. Thumbsuck around 5x40V=200V. As long as that value is somewhere comfortably within the MPPT operating range of 150-425V, you should be fine, it should work, even if it's not bang on the nominal 370V. As long as 5xVoc is not below the start-up Voltage, and 5xVmp is not close to the very bottom end of the MPPT's operating range.

I used to run a set of panels with Voc=260V and Vmp around 210V, so it's not far off from what you're planning here, and it was okay.