Panels in 3 different directions with 2 MPPT? - Blacktown nsw


#1

Dear all,
I am planning to instal a 6.6kw system (Risen 315w x 21panels) with fronius 6kw symo inverter as I have three phase.

Due to the roof orientation I have been advised by the installer that he can place 7 panels in North West, 7 panels in East and the remaining 7 panels in West. More panels (1 or 2) can be installed in North West and West side but he is suggesting to go equals (7 each side)

As per the specifications the inverter have 2 Mppt which to me means that it can only handle 2 strings. As per the installer, the inverter can fit 4 strings and in my case there will be only 3 strings, so I don’t have to worry.

Can someone please explain and confirm if it is okay to have panels installed in 3 different directions and there will be no or very less impact on the efficiency.

Also he has given me the option to install 17 panels x 315w (9 east and 8 west). Not sure if that is a better option as during summers West will receive a lot of sunlight and not that much in the east side. Shading is not an issue as it is a double story house with no trees around. My daily electricity consumption is around 24kw ( 60% day time usage). Will a 5.8 or 6kw system be equally good.

Thanks in advance


#2

Hi again @User1

Good to hear you are making progress of sorts.

Was it the actual accredited installer and/or designer that said that to you, or the sales rep? I hope it’s the sales rep, because unless I am missing something, with 2 MPP trackers (which indeed a Symo 6.0 has) you can only have the array in two orientations. Unless you are using optimisers.

I would say the 17 panel options is a good one, you’d only need a Symo 5.0 then. Although I’d be a bit concerned about these guys quoting you something that would not work very well. Have you checked reviews of the company?

You mean you wouldn’t get much sun on the east because of shading, or because it faces slightly south? If it’s due east, without shading, you’ll get nearly as much as on the west. Western sun feels a lot stronger because it’s hot in the afternoon, but eastern sun provides a very similar amount of light. What time of day do you use your electricity? From what you’ve said above, it sounds like you can fit 9 on the NW roof, why not do that instead of the east?

Cheers
Marty


#3

I’ve done a little research, and there does seem to be a quirk with multiple MPPT, I haven’t heard of this, but I am not a solar technical guru.

Maybe @Svarky can advise us on this one.

Marty


#4

Yes no worries installing panels in two different orientations (east and west) in parallel on one MPPT. The strings just have to be the same length (exact same number of panels). It’s quite common to do this when roof space is limited.

Best to go as big as possible and install all 6kW for your situation.


#5

Thanks Marty. I saw that article as well but was not making sense to me…


#6

Thanks Svarky for getting back to me.


#7

Ah, there you go, didn’t learn about that at design school.


#8

Marty, the guy is from their technical team and at the same time sales … He has some kind of electrical engineering degree. Company review is average.

No we are not using optimisers. I know I can use Symo 5kw (for upto 6.6kw system) but just thinking loud and if in future I want to add more panels then I dont have to upgrade the inverter.

No there is no shading on the east, it is just I have read that for best results the panels should be installed on North or West side.

We will be using the system throughout the day. Maximum during the day using a/c, dishwasher, washing machine etc.

I will wait for few other people to comment on 3 string issue. If it is not viable then I will request them to install Northwest and West.
Thanks


#9

If Jason says it’s fine then it will be, don’t worry about that. In which case, i agree, go with the 6.6 and the Symo 6.0, sounds like a winner :+1: