Hi guys. I need a little assistance please. Thinking of adding a few panels to my system if possibel

I have 10 x Canadian solar panels (420W) on a 5KW Sunsynk inverter. I have attached pics with specs of the panels and the inverter. I remember reading that there is either a voltage limit or amperage limit or both?????

How many more panels can i attach without stressing or risking the normal operation of the system?

What is the effect of mixing the capacity of panels where watts, amps and voltage are different?? Will the new panels only give a max of the lowest capacity panel in the system??

Edited August 27, 2025Aug 27 by Vani
more queries

1 hour ago, Vani said:

How many more panels can i attach without stressing or risking the normal operation of the system?

If you can source the same panel again, you can have 14 panels in total, basically two strings of 7 panels, one string per PV input, with no further questions or concerns. All within spec, all within limits. 10.64A falls within the 11A MPPT limit, then 7 x 48Voc = 336V is comfortably lower than the maximum 500V MPPT Voltage, and lastly, 14panels x 420W = 5880W will be comfortably within the 6500W PV input limit.

I'm not saying this is the only or best panel layout, just that it doesn't push any boundaries, and it's quite possibly good enough.

1 hour ago, Vani said:

What is the effect of mixing the capacity of panels where watts, amps and voltage are different?? Will the new panels only give a max of the lowest capacity panel in the system??

In general your panels will be limited by the current of the lowest-output panel. In this case the 10.64A at STC. More than that, this specific inverter model has a limit of 11A current on each MPPT, at least according to the dataplate, so it will most likely keep clipping current down to that level anyway. Not much point in upgrading to 550W panels or similar, unless your inverter can be upgraded to take 13A input like later versions. At the simplest view, it's best to stick to the same panels or similar in output.

Voltex's website seems to have good pricing currently on similar-output Canadian Solar panels, 455W CS6L, that look to be a close match for your panels, in case you don't find the exact ones again. [Edit: not an 11A panel as I thought. Different specs, different panel]

Disclaimer: Just a personal opinion. To be checked professionally by your installer.

Edited August 29, 2025Aug 29 by GreenFields

Perhaps just to add to that 7 panels per string, that would be 7 panels in series.

The way I remember it

Series = Volts get added together amps stay the same

Parallel = amps get added together volts stay the same

Only when you really want to mix and match odd sizing panels will you play with series and parallel connections between panel to get the max performance out of the mix set to best match the MPPT spec. Hence normally it is just easier to stick with same size panels per string as far as possible.

Thanks very much for the information.

On 2025/08/27 at 1:46 PM, GreenFields said:

If you can source the same panel again, you can have 14 panels in total, basically two strings of 7 panels, one string per PV input, with no further questions or concerns. All within spec, all within limits. 10.64A falls within the 11A MPPT limit, then 7 x 48Voc = 336V is comfortably lower than the maximum 500V MPPT Voltage, and lastly, 14panels x 420W = 5880W will be comfortably within the 6500W PV input limit.

I'm not saying this is the only or best panel layout, just that it doesn't push any boundaries, and it's quite possibly good enough.

In general your panels will be limited by the current of the lowest-output panel. In this case the 10.64A at STC. More than that, this specific inverter model has a limit of 11A current on each MPPT, at least according to the dataplate, so it will most likely keep clipping current down to that level anyway. Not much point in upgrading to 550W panels or similar, unless your inverter can be upgraded to take 13A input like later versions. At the simplest view, it's best to stick to the same panels or similar in output.

Voltex's website seems to have good pricing currently on similar-output Canadian Solar panels, 455W CS6L, that look to be a close match for your panels, in case you don't find the exact ones again.

Disclaimer: Just a personal opinion. To be checked professionally by your installer.

Hi

The 455W CS6L is a really good price. I was also concerned about the 13A of this panel against the 11A of my inverter. But intaller said it would probably only deliver the amps and voltage of the smallest capacity panel. I see you something similar in your response.

I know you said 4 more panels on top of the 10x420w to stay within the 6500W PV input. What are your thoughts on adding 5 more panels? But that would mean that 8 on one string and 7 on the other. Are unbalanced solar strings a problem for a sunsynk inverter?

The 455W CS6L specs below

21 minutes ago, Vani said:

Hi

The 455W CS6L is a really good price. I was also concerned about the 13A of this panel against the 11A of my inverter. But intaller said it would probably only deliver the amps and voltage of the smallest capacity panel. I see you something similar in your response.

I know you said 4 more panels on top of the 10x420w to stay within the 6500W PV input. What are your thoughts on adding 5 more panels? But that would mean that 8 on one string and 7 on the other. Are unbalanced solar strings a problem for a sunsynk inverter?

The 455W CS6L specs below

Both strings of 7 or 8 in the 2nd string is still in the sweet spot. The 2 MPPTS can have a large difference in panel outputs without any harm.

Just a pity it seems Voltex have no stock on a number of their panels.

12 hours ago, Scorp007 said:

Both strings of 7 or 8 in the 2nd string is still in the sweet spot. The 2 MPPTS can have a large difference in panel outputs without any harm.

Just a pity it seems Voltex have no stock on a number of their panels.

Just another point to consider on the CS6L panel is the depth of the frame is only 30mm and not 40mm like we got used to. Also the panel is 200mm shorter on the long side being 1900mm vs the normal 2140mm.

Thanks for the info. Going to have to get new brackets for this set anyway and being installed separately on another roof surface. Voltex in Durban - Briadene has plenty stock.