20KW Solar PV Install Critique or Improve

[OrigamiTiger]

Hi Guys,
My mate is about to embark on a 20KW (50 pieces of 410W/405W) ground mounted solar pv install connected to a 40KW battery system.
We have compiled the following list of components to go with it. What other parts or bits would you add or improve on this install?

The solar panel mix are 40 * Canadian solar 410W and 10 * 405W.
The panels would be run in 4 strings to 2 inverters each with 2 x MPPT inputs. The inverters would be paralleled to each other.

• 12KW Hybrid Inverter x 2 (Deye/Solis/Solax)
• Ferrules
• PV Cable 2 core (positive/negative)
• AC surge protector
• DC surge protector
• 50/75mm electrical cable AC side
• AC battery disconnector
• DC Isolator
• AC isolator
• Generation meter
• Modular batteries Pylontech or Fogstar 5.12KWh battery X 8
• Battery Rack
• Consumer unit

 

[OrigamiTiger]

Anyone ?

 

[MisterSandals]

40KW battery system.

40kWh

The solar panel mix are 40 * Canadian solar 410W and 10 * 405W.
The panels would be run in 4 strings to 2 inverters each with 2 x MPPT inputs.

What is the Voc of panels and what is max PV input volts?

Otherwise, just listing items like "DC isolator" and "Consumer unit" are hard to comment on. Sounds great if its the right one.

 

[timselectric]

Modular batteries Pylontech or Fogstar 5.12KWh battery X 8

This is the only thing that was specific enough to comment on.
Just an FYI.....
Pylontech are 15s, not the standard 16s.
Don't know anything about Fogstar.

 

[OrigamiTiger]

40kWh

What is the Voc of panels and what is max PV input volts?

Otherwise, just listing items like "DC isolator" and "Consumer unit" are hard to comment on. Sounds great if its the right one.

Thank you & correction noted. I see my lack of clear info was my undoing.
The panel specs are as follows

410W (40 pieces)
(Voc) 37.2V (Isc) 14.01A

405W (10 pieces)
(Voc) 37V (Isc) 13.93A

Inverter
Max PV voltage of 800V
Max PV Isc 34 + 17

I am essentially confused on how much panels can go on each inverters considering the max voltage is 800V. Initial thoughts was to go for a split of 26 panels for inverter 1 & 24 panels on inverter 2. The DC isolator sizing should be equal to or greater than the requirements of the system. So far, going for one with a max limit of 800V and possibly 32A. What would you infer is wrong or correct with the set up thus far?

 

[OrigamiTiger]

I

This is the only thing that was specific enough to comment on.
Just an FYI.....
Pylontech are 15s, not the standard 16s.
Don't know anything about Fogstar.

Thank you for commenting.

I think I understand the Pylontech which is 15s x 3.2V=48V x100Ah =4.8KWH. The latter is probably 16s.

The battery sizing is what I am thinking of, a 40KWh against 20KW installed pv?

The location is in West Africa with 6 hours or more minimum sun hours and likely could be getting 80KW+ per day. The building would be using substantial amounts of the power generated.

 

[MisterSandals]

max voltage is 800V. Initial thoughts was to go for a split of 26 panels for inverter 1 & 24 panels on inverter 2.

13 x 37Voc = 481Voc
This is easily within the 200-650V MPPT (optimized) range for each MPPT input.

This is a giant installation and will involved deadly voltages almost everywhere. Don't skimp on anything and have plenty of quality disconnects and fuses/breakers.

 

[MisterSandals]

The building would be using substantial amounts of the power generated.

Using power as it is generated will lower your battery requirements. With 6 solar hours, that means 18 hours running off of battery. Calculate your needs for these 18 hours daily and the number of days (24h) that you want to store for cloudy days. This will be your battery size in kWh (see how the units, when done correctly make the numbers easy?).

 

[OrigamiTiger]

Great stuff. Thanks for the advise. We are planning on multiple lines of protection including inline fuses, surge protectors and many others.

13 x 37Voc = 481Voc
This is easily within the 200-650V MPPT (optimized) range for each MPPT input.

This is a giant installation and will involved deadly voltages almost everywhere. Don't skimp on anything and have plenty of quality disconnects and fuses/breakers.

 

[dougbert]

NEC limits residential to 600VDC max

victron smart shunt for metering, unless I missed one listed

 

[OrigamiTiger]

NEC limits residential to 600VDC max

victron smart shunt for metering, unless I missed one listed

Hi Dougbert, Not American.
It's a project to be installed in West Africa.

 

[dougbert]

Hi Dougbert, Not American.
It's a project to be installed in West Africa.

then go for it, nice

 

[SeaGal]

I think I understand the Pylontech which is 15s x 3.2V=48V x100Ah =4.8KWH. The latter is probably 16s.

The battery sizing is what I am thinking of, a 40KWh against 20KW installed pv?

The location is in West Africa with 6 hours or more minimum sun hours and likely could be getting 80KW+ per day. The building would be using substantial amounts of the power generated.

The Fogstar battery system is standard 16s (=5.1 kWh) per rack.

As @MisterSandals said, you will need to calculate your energy requirements for when there is no sun. Obviously that will depend on whether most usage will be in day or night, or evenly split.

In my mind, 40kWh of battery doesn't sound enough for a 20kWp PV installation, but you will need to run the figures yourself. Presumably you get a lot more sun in West Africa than the UK and is less seasonally variable due to your proximity to the equator? Our 15kWh of battery is only just enough for 6kWp of PV... one day will invest in more! Others on here have talked about kWh of battery being ideally 4 to 6 times the kWp PV number... but that will depend on usage hence YMMV.

 

[OrigamiTiger]

The Fogstar battery system is standard 16s (=5.1 kWh) per rack.

As @MisterSandals said, you will need to calculate your energy requirements for when there is no sun. Obviously that will depend on whether most usage will be in day or night, or evenly split.

In my mind, 40kWh of battery doesn't sound enough for a 20kWp PV installation, but you will need to run the figures yourself. Presumably you get a lot more sun in West Africa than the UK and is less seasonally variable due to your proximity to the equator? Our 15kWh of battery is only just enough for 6kWp of PV... one day will invest in more! Others on here have talked about kWh of battery being ideally 4 to 6 times the kWp PV number... but that will depend on usage hence YMMV.

Thanks for contributing SeaGal,

We have indeed thought about that and would be adding more batteries in the future hence a modular system is required. I was trying to be very very conservative with the amount of power this would likely generate . It is more around 9 -12 sun hours a day and potentially looking at closer to 120KW a day especially at a spot just above the equator where sunlight is ample. The reason for such a big setup is that its for use with a fairly large property.

There's a guide for much daily usage to expect based on the appliance wattage ratings in the property though I would have preferred to see an electric bill to show trends of consumption which isn't forthcoming.

Also spoke to an American guy with same 20KW PV installed, his battery bank is around 75KWH and states he generates closer to 120-180Kw during summer.

 

[SeaGal]

Modular sounds like a good approach then

And to save @MisterSandals from replying, I'll correct the following ?...

It is more around 9 -12 sun hours a day and potentially looking at closer to 120KW a day

120kWh

Also spoke to an American guy with same 20KW PV installed, his battery bank is around 75KWH and states he generates closer to 120-180Kw during summer.

120-180kWh