I feel like this has been discussed before but I can't find anything on it.
Customer has 2 arrays and 2 Classics.
We propose to use a physical relay to switch the input off one inverter when the batteries are full and onto a SQ Flex when they need to pump water.
Are there any problems with removing the input from one of the CCs like this?
You will be using a relay to switch HV DC, so arc will be a problem.
Might want to use a MAKE-before-BREAK relay, so that the switching only involves a portion of the PV output instead of all of it.
Or some SSR rated for DC and properly snubbed to avoid spiking
I have seen this work in the past with diodes as well so the array is split between both devices, the issues are:
A- You dont want one MPPT controller (IE classic or Grundfos) back feeding the other, so diodes work
B- The Grundfos wants priority, I seem to recall this works ok as is but if the Grundfos has a way to send a contact closure or contact open on need the Classics Aux1 could be set to one of the input modes that disable it when the Aux two is active low or active high. I believe the pump controller has this function
So use diodes and use the Aux2 active low or active high function.
PM me if you need more help por clarification
I believe these IGBT transistors are supposed to be able to handle switching high voltage .
https://www.ebay.com/itm/igbt-transistor-Semikron-SKM-400GB-123D-400A-1200V-BRAND-NEW/292553916274?hash=item441d927f72:g:nlMAAOSwjqVZE4nD
Maybe there are less expensive lower voltage versions of IGBT - I have heard of them but never used them before but sounds like they would do the job.
Larry