Adding panels to an existing off grid system

[SunEagle]

Thanks for assistance
I'm learning as we go.... now I realise I can't add more power (even wired creatively)

My battery bank is 8 x 6V/225AH batteries wired for 24volts

Actually that CC is a PWM type and not an MPPT type. That will usually allow you to have more panel wattage wired to it but in the long run you will lose about 33% of the panel wattage for charging based on how a PWM type works.

PWM - amps in = amps out
MPPT - watts in = watts out.

Your 450Ah battery system should be able to handle 45 charging amps but you will lose that 33% of panel wattage getting there.

[olmec]

Thanks for assistance
I'm learning as we go.... now I realise I can't add more power (even wired creatively)

My battery bank is 8 x 6V/225AH batteries wired for 24volts

[SunEagle]

Thanks for your input Bala. I understand what you are saying. Would it be possible to reconfigure the panel wiring to increase the voltage while keeping the wattage under the 1500... this is how it works right?

No. An MPPT type CC usually has a max input wattage based on the voltage of the battery being charged. I believe that CC is rated 50Amp which would probably max out at 1200 watts for a 24V battery system. You currently have 1600watts which is probably hurting your CC. Adding any more wattage would not help you. You would either have to add a second CC for the additional panels or increase the size of the CC to handle your total wattage.

By the way you never mentioned the Ah rating of your battery system. The Ah rating will need to be between 8 and 12 times the amp rating of your charging amps.

[Bala]

Thanks for your input Bala. I understand what you are saying. Would it be possible to reconfigure the panel wiring to increase the voltage while keeping the wattage under the 1500... this is how it works right?

Sorry I cant answer that, i dont know enough about how your charge controller works.

I would assume that 1500w is the max input at any voltage or they would stipulate but someone else may verify for you.

[olmec]

Thanks for your input Bala. I understand what you are saying. Would it be possible to reconfigure the panel wiring to increase the voltage while keeping the wattage under the 1500... this is how it works right?

[Bala]

Looking at the specs I read the maximum wattage for PV array as being 1500W so I would assume you need to stay under that. If you were to put more panels on the south roof you would need to turn off panels on the north roof to stay under spec?

http://www.easunpower.com/content/?928.html

My panels are on the North roof and the Sun is now south of centre. My panels are only on a 10 degree pitch roof so they still do fine at this time of year. If it is an option you could look at changing the angle of your current panels.

[olmec]

Hi all,
I have an off grid system with 8 x 200W panels @ 24V wired as 4 series pairs in parallel.
There are mounted on a north facing roof at an angle of about 20-30 degrees and output November 25 @ 3:50pm was 1200W / 64v (I am in the southern hemisphere)

Ideally I would like to add another 8 panels on the other side of the roof (south facing at similar angle). In our summer this gets almost as much sun and I use the power for irrigation pump and deep freeze.

Inverter / battery charger unit is ISolar SM 3KVA 24VDC Plus
Solar Charger mode:
Rated power 1500W
System voltage 24VDC
Operating voltage range 30/115VDC
Max solar voltage (VOC) 145VDC

My Questions are: Is this doable with the charge control unit I have and what are the implications of having panels facing different directions? Am I right thinking that panels with higher output are reduced to lowest output of any panel in the array?

Thoughts and advice much appreciated.