question

giles avatar image
giles asked

How to match the PV array to the MPPT

Hi I have 20 x Hisunage 250w panels rated at 37 Voc.

They are wired in 5 strings of 4 so thats 4 x 37= 148 V max that those panels can produce in perfect conditions.

The charge controller is a Victron MPPT 150/85 and its rating is stated as 150V absolute max coldest conditions 145V start up and operating max.

In certain conditions I get an error code 33 high input voltage and on the Colour control CCGX the read out from the PV watts fluctuates wildly up and down until at some point it settles down.

Has my system been wired/designed incorrectly? what damage is being done and what would be the solution?


charge controller compatibility
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2 Answers
JohnC avatar image
JohnC answered ·

Hopefully your kit hasn't been damaged yet. You're 'sailing too close to the wind' with 4x series wiring. Get them rewired to 3x. You'll have 2 orphans from that process,

If it's a diy job, suck up your error and carry on. If a pro installer did it, demand a fix and a rebate for the orphans, or an extra panel for nix of course. :)

You *must* fix this.

Edit/: A replacement with a 250/xx mppt is another option. A quicker fix, but if it's an installer error, his request for more money to cover it is for you to decide upon..

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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Giles; Please follow JohnC's advice.

In answer to your general question;

Victron has an MPPT sizing tool available here. You can use it to enter in your panel specifications and configuration and it will recommend an appropriate MPPT to use. You can also use this tool in 'reverse' to enter your solar details and then adjust their installation parameters (parallel and series) until they match your MPPT.

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