MIx-Match Canadian Solar Panels

[hancock]

Hi Guys I really need your advice right now @plonkster

Currently have 6 numbers 330W Canadian solar Panels in 3S2P hooked up to an Axpert King (used to be a Morningstar Tristar MPPT 60A which I have retired)

Looking forward to double it to meet up to the 4000W and 145V limit of the inverter. unfortunately, my local suppliers don't have the 330W in stock anymore.

They only have 305W, 375W and 385W available.I am looking at adding 375W in 3S2P to the equation as a last resort. Is this advisable? 

330W data is voc=45.6,vmp=37.2,isc=9.45,imp=8.88 while for 375W voc=47.6,vmp=39.8,isc=9.93,imp=9.43

What possible scenario / option do I have to take to not exceed the 145V max of the inverter and at the same time add up more panels.

 

thanks

[Jaco De Jongh]

6 hours ago, hancock said:

unfortunately, my local suppliers don't have the 330W in stock anymore.

I will be able to supply the 330 Canadian (72Cell) on the 6th of December. I do however  have 330 in a different make with almost the same specs in stock.  Let me know if you are interested.  

[hancock]

Hi @Jaco de Jongh 

Thanks for the reply. Unfortunately I am in Lagos Nigeria not SA

Looking for a quick solution I can come up with locally that will not involve importation

 

Thanks

[Jaco De Jongh]

7 hours ago, hancock said:

I am looking at adding 375W in 3S2P to the equation as a last resort. Is this advisable? 

In short, the 375W will be limited to approximately 330Watt. As long as you know you will not get the full 375 Watts nothing stops you to use them as a last resort. 

 

53 minutes ago, hancock said:

Unfortunately I am in Lagos Nigeria not SA

Thats a pitty. I am not ready for export yet..  

[hancock]

14 minutes ago, Jaco de Jongh said:

In short, the 375W will be limited to approximately 330Watt. As long as you know you will not get the full 375 Watts nothing stops you to use them as a last resort. 

 

 

Well, if the 375W in 3S2P arrangement will not exceed the max 145voc recommended by the inverter  and limits itself to the 330W ,then I don't mind this. just want to be sure there wouldn't be any other issue

Yea I know shipping/export/import do suck sometimes and come with its headaches. 

my shipper misplaced my Pylontech cables from china and he wasn't really happy having to pay for the full purchase and shipping 

Edited November 17, 2019 by hancock

[Ironman]

I have also used mixed panels for many years.  The best way to run them:

- Get panels that do not differ by more than 15%.  

- Make one string with each kind of panel. Do not mix different panel ratings in one string.

 

- If possible, keep the strings separate and use separate MPPT's for each string.

- If not, and you have to put these strings in parallel on one MPPT: it will hunt around and find the maximum power point for all panels together.  It adjusts the voltage and current drawn from the panels in a "searching" algorithm, while testing the power delivered (volts X amps).  As the voltage goes up, the current comes down.  As the voltage goes down, the current goes up.  And all the time it tests - what is the power - should the voltage go up or down?  So the MPPT "hunts around" for the maximum power point.

- Using mixed panels like this, the overall maximum power point voltage will be at the maximum power point (Vmp) of the weaker panels - the stronger panels will deliver their normal current, but at the (lower) voltage of the max power point of the weaker panels. More or less.

So if you use 330 Watt and 375 Watt panels in parallel, you should get about the same as if you only had 330 Watt panels. The 375W panels will be derated to 330W each, as @Jaco de Jongh said.