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tpwchr avatar image
tpwchr asked

Which MPPT is best for this use?

Hi everyone. I am going to install 8 solar panels of 450Wp towards East and 6 panels towards West, therefore i need two MPPT's.


Thinking in the possibility of adding more solar panels in the future, in the West area i could add up to 12 in total, that would give me a Voc of 149,1V and Isc of 45,28A. Having in mind that the MPPT 150/85 has the limitation of 145V in maximum power and during start, would you install the 250 instead?


Also, can I mix two different MPPT's? For example one 150/85 for the West and a 250/100 for the East?


And do you connect them together or just separately to the Cerbo?

MPPT Controllers
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Vance Mitchell answered ·

You can definitely mix different MPPT controllers in your system. I would consider using two controllers now and adding a third if you expand the system.

I would go to the 250/100 if you are that close to the maximum panel voltage to allow for cold weather increases.

Remember also that the second number refers to the output amps to the batteries, so a 250/100 can handle around 5000w on a 48v system (6000w is possible but might not make full use of the panels).

Have you tried using the MPPT calculator it will give you recommendations once you enter all your panel details.

As far as connecting them together, it depends on which controllers you use. Ve.direct go direct to the cerbo (or other GX device), and Ve.can get daisy chained with a terminator at each end of the chain.

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tpwchr avatar image tpwchr commented ·

@Vance Mitchell thanks for the link.

My plan is to use the two MPPT's with pylontech batteries and the cerbo. I see that it has 3 VE.Direct and 2 would be used by the 2 mppt's if I buy the normal ones.

And the pylontech would use the VE.Bus.

But how would I connect the two MPPT's to the pylontech batteries? Would i need a bus bar if I need two MPPT's?

Thanks!

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tpwchr avatar image tpwchr commented ·

BTW, I used the calculator, and it shows me a list of MPPT's. Are these the only compatible or are the recommended? Because for 6 solar panels recommends 150 ones, but if I go in the future for more and I add another parallel, it jumps to 250.

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Vance Mitchell avatar image Vance Mitchell tpwchr commented ·

You can generally use a larger than specified controller without any issues.

The calculator is more a case of the minimum to use.

You are best to work off the recommendations for your future system to avoid buying a controller that you will have to replace in the future.

The only downside to this, is a slightly larger idle current usage.

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tpwchr avatar image tpwchr Vance Mitchell commented ·

Hi. Does it lose efficiency for using a 250 instead of a 150? Calculator would recommend me 250/70. I hope there wont be problems for using a /85

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