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Need help with controller


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Hi all


really need help with the following:


the guy that sold me my system 2 years ago has gone awol and I need to replace the controller he installed. I need help working out the best controller to buy. My system is as follows:


9 x 100 watt mono crystalline panels

5 x 24v battery bank

3 kw inverter


I had a 40amp PWM controller which started over charging and burning until I disconnected it.


I think that I should get 2 more batteries and make the bank 48v and then get a 30 amp MPPT controller or leave the batteries as is and get a 60 amp MPPT controller. Would appreciate the pros and cons of these.


I'm not an electrician.


Can you recommend any decent fellow that can do installations as well.




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How many volts is your inverter? You will need to match your battery bank, MPPT and inverter to the same voltage. I would imagine your system is currently all 24V, so best to stick to that. 


Any electrician should be able to sort you out with the installation.

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Hi Yeah, my inverter is 24v.


Ok, so at 24v I would need a controller of: 9panels x 100watts  = 900watts/24v = 37.5 , so a controller 50amp or more?


Is there anything else I need to look at on the controller?


Read something about total voltage capacity from panels need to be catered for.


MPPT or PWM? a 60amp MPPT is a lot pricier than ea 60amp PWM

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Go for the MPPT the extra cost will allow you to benefit fully from the 900w of panels you have. PWM is older technology. I actually have one on a remote gate with a 80w panel on it. Under those circumstances the small increase in efficiency does not warrant the extra cost.  

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Ok, so 900W at 24V is 37.5Amp.

So, if money is very short, go for the 40Amp MPPT controller.

MPPT works much better than PWM and should keep your battries full for longer.

If money is not too short, go for the 60Amp unit.


How is your PV panels currently configured? All in parralell?

What is the voltage on those PV panels?

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