I am looking at replacing an Axpert (Voltex MKS 5kVA) with a Sunsynk 5kw inverter that can do blending.
I currently have 4kw PV array consisting of 10x400w Panels (41.6V by 9.6A with OC 49.1V)
For the Axpert I user 5 String of two panels each as PV input for the Axpert with min PV in 40V and Max is 115V, and 80A max, that gives my axpert a theoretical input for my setup of 82.4V and 48A as input.
The Sunsync has two MPPT’s, with Startup 150V, and operating volts as 125-425V with max 500V
At this stage I do not want to purchase additional panels or climb on roof and rewire the strings and would like advice or views on, just wiring all strings in series (doing this at the PV combiner box) giving me a setup of 416V with Open circuit max of 491V.
This is however still in limits of the Sunsync but very close to the operating and Max volts of the Sunsync.
Any viewpoint why I should not do this as first interim choise
If the above is not recommended I can bite the bullet and climb on the roof and potentially rewire to two strings of 5 panels each and connecting one string to each of the MPPT’s giving me input of 208V per string.
Currently all panels same angle and minimal shading very early in morning (bottoms 2 panels) or very late in afternoon (left 5 panels)
Putting all the strings in series should be ok, the only thing I would be concerned about is whether the Sunsynk can handle 4kW on only one MPPT. Otherwise you may want to make a string of 6 and a string of 4 (can be done without climbing on the roof) 4s should be enough to make the MPPT start and run.
Edit: 10s may be a bit close to the 500V limit, especially when cold. You may want to check if the 500V maximum is a hard limit.
Thanks Stanley,the 6/4 option sounds like a very doable and safe option to get the inverter up and running, I will communicate in mean time with Sunsync on that max limit.
I received feedback from Sunsynk support (responce was quite good)
My Question to them:
If I connect all the strings in series, I will have 10 panels in one string input into one of the SunSynk’s MPPT’s
This will mean nominal input voltage will be 416V but the max VOC will be 491V.
Question:
With the max VOC of 491V being very close to the max inverter input voltage 500V would this be an issues, ca I temporary run with this ?
At some time when I get to rewire the strings I could do
a. two strings of 5 panels each, for each of the two input Mppt’s
b. two string 4 panels in one and 6 panels in other
Any recommended option for the PV array I already have ?
Their response:
a).With the max VOC of 491V being very close to the max inverter input voltage 500V would this be an issues, ca I temporary run with this ?
** This is issues.I think the voltage is too high. I don’t recommend using such a high voltage. Voltage＜450V.**
b). two strings of 5 panels each, for each of the two input Mppt’s
** Yes. I choose this. I think each string should have the same number of panels.**
Just an update, completed installation over the weekend and have setup the two strings of 6 and 4 panels each, happy so far, with the intermittent sun today it peaked at 3.6kw+, here is two screenshots taken with production above 3kw
Still trying to figure the setting out 100%, It did switch on and off intermittently (and pushed geyser temp to 60deg today), but I did not have the time to fully evaluate the setting at the time of switch on or off.
I had the Aux value set to 800w but read this is the setting for max aux export, while I thought this is the setting when you have more than 800w spare (after load and non essential) to send to aux. The geyser element draws 960kw and did switch on as can be seen above, at some time when PV dropped due to cloud it stayed on and did draw extra power from utility with the Aux on.
Hi @Ryeman, you mention that when pv dropped due to clouds, the geyser stayed on, powered by utility, thought the parameters were excess and a very small battery soc window
Might be best to start a new threat on this for the Aux settings and behaviour, as I am also seeing inconsistent behavior to my understanding of when an how this should trigger
Will take some screen shots tomorrow and see if i can catch this and better determine the conditions of on vs off.
