Solar - have I missed anything??!

[Whodat]

Hi everyone, long time lurker first time poster.

 

Am planning on self-installing solar. Before I go ahead and do this, can someone tell me if what I’m saying seems correct, or I’ve got something wrong.

 

Inverter

I’ve already got battery storage, with a Solax x1 hybrid gen-4 inverter fully installed which has the following:

Start voltage – 90V

MPPT voltage – 70-550 with a “MPPT full power voltage” of 190-480V and max input current of 14A and max short circuit current of 16A.

 

My weird roof

My roof is a very funny shape, so I only have space for 3 panels facing ESE at a 12⁰ angle and 3 panels facing SSW at 12⁰ angle. This is two sides of a first floor wrap around extension so the ESE start to get shaded from about 3pm in summer.  Also a lamppost close to the house will partially shade the SSW panels in mid to late afternoon.

 

The plan!

I am planning on the Perlight 400W delta blacks which have a Voc of 49V, Vmpp of 41V and an Isc of 10.1A.

Plan is to put them all on one string with Tigo optimisers on each. My thinking is the ESE get light early, 150V Voc and 121V Vmpp is enough to start the inverter and operate it in MPPT range, albeit I assume not fully efficiently. SSW come online about 11am and everything is hunky dory, then as the ESE get shaded the SSW panels keep everything running as they also have 150Voc and 121 Vmpp. Optimisers mean the mixed orientation and shading is not a dealbreaker.

 

Am I right?

My specific concerns are that I can’t mix the orientations on a single string in practice, or there is something that means that except in the sunniest conditions I won’t get output (although looking at the voltage curves at different irradiences it doesn’t seem to make much difference as it more affects current?). I’m not worried about it being the optimised efficiency or payback as that’s not why I’m doing it – I’m just keen to do it unless it is basically pointless!

 

Let me know!

[billt]

1 hour ago, Whodat said:

My specific concerns are that I can’t mix the orientations on a single string in practice, or there is something that means that except in the sunniest conditions I won’t get output (although looking at the voltage curves at different irradiences it doesn’t seem to make much difference as it more affects current?).

 

If you're using Tigo optimisers you can use modules with different orientations, that's one of their selling points.

 

One of my systems has 4 modules on a 38 degree roof facing more or less south, 2 modules on a vertical east facing wall and 2 modules on a vertical south facing wall. They all have Tigo optimisers and the system works. I did this because the roof panels didn't have a high enough voltage to start the inverter and there was no more space for panels. The extra panels don't provide much energy, but they raise the voltage enough to make the inverter start. It wouldn't work without the optimisers though.

[Whodat]

Thanks billt!

 

Can anyone confirm my voltage calcs appear correct and nothing glaring else I've missed?

 

 

[Dillsue]

Not sure how the Tigo optimisers work but if you were using solaredge optimisers you dont need to worry about MPPT input voltage as its regulated by the optimisers. All thats required on an SE system is for a minimum number of panels/optimisers to be in daylight, from memory its 8, and thats enough to get the inverter operating. Only time you need to consider panel V/I specs is when matching panels to optimisers.

 

If the Tigo versions work in the same way you probably just need to check minimum system specs to make sure that 6 optimisers is enough to get things working