question

beov44 avatar image
beov44 asked

Input on off-grid system

Hello everyone,

I have a plan for an off-grid system that I wanted to run by you guys for input:

Solarpanels: 32 x 420w Sunpower tot 13.4Kw (already purchased) will be installed to fit with the MPPT (string and parallel)

Inverter: 3x Victron Energy Quattro 8000 Watt 48 Volt Inverter & 110 Amp Battery Charger 230 VAC

MPPT: 4x SmartSolar MPPT RS 450/100

2x BYD Battery-Box Premium LVL 15.4

1x Victron Color Control GX

If anyone has any input (good or bad) I would appreciate it.

Thanks,

Bettina


offgridsystem design
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

8 Answers
wkirby avatar image
wkirby answered ·

4x MPPT 450/100 seems a bit overkill unless you plan to significantly increase the size of your array in the future.
3x MPPT 450/100 would offer more than 15kW of charge power from PV and you'd have six separate trackers altogether. Still room foradditional PV capacity.
2x MPPT 450/100 would offer more than 10kW of charge power. This is lower than your array capacity of course, but unless you have pure sunshine for days on end then you'll not always see the full 13.4kW anyway. You'd have four separate tracker. Alternatively 1x MPPT 450/200 would offer the same as 2x 450/100.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

JohnC avatar image
JohnC answered ·

Hi @Beov44

Why the 3x Quattros? Maybe for 3 phase loads, but one of the advantages of being truly offgrid is that you're not subject to power utility constraints. And I'd prefer a single phase over multiples if the load requirements suit.

Why the 110A battery charger? And why Quattros and not Multipluses?

Excuse the questions, but you don't tell us enough about what you actually want to do..

1 comment
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

wkirby avatar image wkirby ♦♦ commented ·
I think they mean the 110A charging cpacity of a 8kVA Quattro rather than a separate charger.
0 Likes 0 ·
ponzoa avatar image
ponzoa answered ·

I agree with the above and would add that personally, I like the Cerbo a LOT more than the colour control GX. More power and flexible unit with more connections to grow with.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

beov44 avatar image
beov44 answered ·

Hi @JohnC, @WKirby, and @ponzoa!

Thank you for your answers, I really appreciate you taking the time for the feedback!

For the 3 phase question, there is some history. Being very new to these kind of systems, we asked an online vendor to suggest us a system that would work offgrid. Unfortunately, they sold us a system (3 phase inverter with high voltage batteries) that only works as emergency power supply when offgrid and therefore not nearly at full capacity (approx 25% only). We now need to replace the entire system because we do not have (and it is not possible to get) grid access. Since the electricity of the house has now been installed to fit with a 3 phase system we want the new system as 3 phase as well.

Background on the house is that there is a lot of appliances that need electricity, eg, well pump, a pump for the cistern, swimmingpool, whole house dehumidifier and air exchange, air-to-water heatpump, induction cooking plates, oven, towel heaters etc.

We would like the Quattro because the Multiplus only goes to 5000 VA, and we would like to use the Quattro 8000 VA to make sure we have enough power for peak loads.

For your question about the 110A battery charger, I checked the BYD Battery-Box Premium LVL Minimum Configuration List and it was compatible with 110A for offgrid systems. Is there a specific upside to use the 200A? Sorry, like I wrote at the top, I am new to this so still learning.

With regards to the MPPT, I did all the calculations for the maximum VoC etc, and also used the victron online calculator and the result that came out was that with our solar panels we could add 4 panels in a string with 2 strings in parallel to each MPPT (the max VoC is 83V/panel). I might have misunderstood something so I will check again. However, we would like to keep the option to increase the system, including the size of the battery pack in the future.

We will for sure get a Cerbo GX, this was a misunderstanding from my side that the touch screen was a standalone when in fact it is just an optional screen used for the Cerbo GX.

My goal is getting feedback on this system to make sure we don't end up with another super expensive mistake.

Thank you all!

Best,

Bettina

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

ponzoa avatar image
ponzoa answered ·

The Multiplus II actually goes up to 15KVA and can be installed as a 3 phase system. However, you can only put in parallel units up to 5KVA in the Multi II range. Something I help is solved soon.


Basically, if 15KVA per phase is sufficient, you can go Multi II if you like (don't do the GX type - external Cerbo is better).

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

beov44 avatar image
beov44 answered ·

Thanks for the input Ponzoa!

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

rikhf avatar image
rikhf answered ·

Hello Bettina, as said already maybe you should consider 3 x Multiplus II 48/8000/110. You can use 1 of them for charging with 230V/110A even when they are in 3 phase config. (I assume you have a 230V genset on site?)

About the solar chargers, you can save yourself a lot of money going with only on 1 MPPT RS 450/200. Make strings with 4 panels and 2 parallel per string. The max output of this charge controller is 200A which is 10.2kW at 51.6V. That is very nice compared to your panels Wp.

And yes, go with the Cerbo.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

beov44 avatar image
beov44 answered ·

Thank you @rikhf!

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.