Combing Series of different Panels

[mcinmylo]

Hi All,

A couple questions on solar panels. I am looking to upgrade my PV array but I have questions on solar panels. I have 4x 100W Renogy Solar Panels. With a new MPPT controller I am able to run higher voltages from a better spot on my property.

I am looking to run:
- 1 Series of 4x Renogy 100W panels (400W series)
- 2 Series of 2x Canadian Solar 330W panels (have not bought yet) (660W per series)


Using Magnum PV calculator with the panel specs.
It showed that the renogy series would be outputting:
- VMP 75.6V at 25C, 89.2 at -35C
- PV current of 5.3

The Canadian Solar Series
- VMP 74.4V at 25C, 88.2 at -35C
- PV current of 17.8


Is there anything I should be aware of, or that I am missing when using mismatched series and combining them - mainly on the voltage mismatch? Looking to run the array into either a Midnite Solar 150 or Magnum PT 100.

Thanks,

[inetdog]

The general rule of thumb is that you can parallel strings of panels whose voltages differ by no more than 5% into a single MPPT input with no significant loss of total power.
Similarly you can put panels whose current differs by no more than 5% in series without excessive loss.

Is the nominal voltage of the Canadian Solar panels really twice that of the Renogy panels?

[mcinmylo]

Okay good to know, I tried to match panels that would work with my current panels the best i.e: closest voltage. The Canadian Solar Panels are double. So having 4 100w 12v Renogy's and 2 Canadian Solar Panels matched up closely for voltages.

[SunEagle]

If you wire the 2 x 330w Canadian panels in series you will get 8.9 amps not 17.8 amps. They have a Vmp = 37.2v and an Imp = 8.87a.

[mcinmylo]

If you wire the 2 x 330w Canadian panels in series you will get 8.9 amps not 17.8 amps. They have a Vmp = 37.2v and an Imp = 8.87a.

You are correct! My calculator showed me the output of two series of two, one series would give 8.87A

[SunEagle]

You are correct! My calculator showed me the output of two series of two, one series would give 8.87A

You should be able to wire the 3 sets of panels (4 x 100w in series), (2 x 330w in series) & (2 x 330w in series) in parallel to an MPPT CC with fusing for each of the 3 "strings".

But with 1720 watts of panels you will have to go with a 24V or 48V battery system since a 12V battery is limited to about 1000 watts.

[mcinmylo]

You should be able to wire the 3 sets of panels (4 x 100w in series), (2 x 330w in series) & (2 x 330w in series) in parallel to an MPPT CC with fusing for each of the 3 "strings".

But with 1720 watts of panels you will have to go with a 24V or 48V battery system since a 12V battery is limited to about 1000 watts.

That is what the plan was.

I am a little stuck with 12v at the moment. Using a Midnite Solar or Magnum MPPT PT Controller I calculated my output would be around 95 amps (using that same magnum calculator and inputting the specs of all three series of panels). I currently have an 1100AH battery bank at 12V. I know it is better to be higher voltage - any big bad reason this setup would not work at 12v?

[littleharbor]

It may work, but not well. That's a high Ah battery bank. Care to describe how it's wired and what batteries you have?

[Mike90250]

.... I currently have an 1100AH battery bank at 12V. .....

It's far more expensive to run all that fat cable to handle 500A @ 12V. than 120A @ 48V.

[mcinmylo]

We have 6x US L16 6v. 385Ah each. With the high voltage going to the controller and then only a short distance to run from controller to batteries, should not be too bad for wiring. Not ideal of course.