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cruisey1987 avatar image
cruisey1987 asked

Oversize a Quattro for future expansion?

Hi all,

I'm considering a system which will consist of 6.75kWp solar panels, Smart solar 150/100 MPPT, an 8kVA Quattro and 6-8 Pylontech 2.4kWh batteries

I'd like the possibility of expanding the system in future with another 6.75kWp of solar and more batteries

Obviously this will take me over the limit for the Quattro, so I'd need another one

Alternatively, I can get the 15kVA Quattro for less than the cost of two 8kVA Quattros.

I'm wondering if there is any disadvantage to using the 15kVA Quattro with a much smaller array until the system is expanded?

Would the disadvantages outweigh the simplicity of not needing parallel Quattros?

MultiPlus Quattro Inverter Charger
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Alexandra avatar image
Alexandra answered ·

@cruisey1987

You size the inverter for your peak loads. So will an 8kVa cover your loads fully? And will it continue to do so in the future?

Battery bank is sized at minimum for the inverter, if you do not need storage really. Or it is sized for a number of days of autonomy (in other words how many days running without being able to get a full charge do you want). An example is a house that uses 25kwh of power a day, needing 3 days or so of backup would need at least a 75kwh stack of batteries.

Then you size your solar to run the 8kva at full 8kva load and then add more for max charging current for the bank (possibly even a bit more for not so sunny days.) If you start with 8 pylons then you can easily add 200Amps more of charging from solar.

The system GX will throttle the mppts as is needed so how much is too much?

If you start with a 15kva then you need to meet the minimum requirements with 10 x 2.5 pylons as you should not undersize a bank for an inverter (not safe). You can always undersize solar and add later.

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cruisey1987 avatar image cruisey1987 commented ·
Thanks for that, I should mention that it'll be an ESS system with a 16kVA grid connection, so the Quattro will be pulling from the grid when it can't cover the demands with Solar.

I believe the 8kVA can feed through 23kW so I believe I'm safe in that regard

I see your point regarding the minimum battery size. I would probably add more batteries when expanding the system, but it seems like unnecessary expense at the moment

So it seems best to go with 8kVA and add another Quattro when expanding the system


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