Electrical – How to run a fridge on off grid system

12vinverterpower

So I live off grid and have a 12v solar system with an array of batteries and a 12v 45amp MPPT controler. I also have a 1000w inverter for things such as powering my laptop and things.

I have recently bought a fridge however I am having some issues powering the device as when the compressor starts it will surge at around 750w. My MPPT controller does not go this high (and I have not been able to find any that will) and so the compressor will not start correctly and just make clicking noises while the inverter complains that it does not have enough power.

I have tried removing the MPPT from the circuit and just having the batteries go directly to the inverter which seems to work fine however it means I will have no undercurrent control over the batteries. Ideally I would like everything to go though the MPPT controller.

I am looking into soft start devices such as this one to slow the start up draw of the compressor however I am not sure if this will allow the compressor to start correctly.

I was wondering if anyone has any ideas or solutions to to this problem.

Thanks!

Best Answer

The inverter itself if it is thought for offgrid application should have the undervoltage protection. So you can connect the battery directly to the inverter. This is how it is normally done in off-grid solar appplications and the MPPT charge regulator is only for the DC loads and regulating overvoltage while charging. Otherwise you would need to always oversize the charge regulator.enter image description here

See an offgrid circuit schematic of one of my projects

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