Step 1 of the spa system

[LouiseSJPP]

I'm designing an island system to run my spa. It's a panel-led design as I can absorb all the energy produced, I need a roof for my log store and the size I an make it is limited by the property constraints.

The panels I'm looking at (https://www.leroymerlin.es/producto...solar-ja-solar-405-w-full-black-90349686.html) are full-black 405 watts. I can fit an array of six. One ide of the array is against the higher wall of the house, and thus will have some shading: a little bit of sun shading on the far right side before midday, and thereafter, from the right to the left, diminishing obstruction of the blue sky. For this reason, I'm thinking to make the array three pairs of panels to minimise the impact of shading across the array.

Is this sound thinking? If so, do I put an MPPT on each pair? I've seen something called a panel optimiser, but suspect this is for AC output, whereas I'm going to battery and inverter.

I think I'll be at best 75% of the 'normal' output, given angle and skope, of the panel (https://globalsolaratlas.info/detai...&c=42.510577,-3.131104,8&pv=small,150,22,2.43) because I have a steep hillside and trees to the north, and a mountain range to the south, neither affecting direct sunlight but both impinging on blue sky. Can I safely knock down Isc of the panels for this and the non-optimal panel orientation when sizing MPPT and inverter?

 

[sunshine_eggo]

You need to avoid shade at all cost. Shade is devastating. If shade can't be avoided, it must be mitigated.

Please review to understand how shading impacts PV:

In portrait orientation, shading a single cell will cut out 1/3 of the panel. Shading a whole row of cells will kill the output of the panel entirely.

Tigo makes DC-optimizers. They do improve performance.
All panels in a string need to be facing the same direction.
All strings in parallel must have the same voltage.
Parallel strings in adverse conditions can behave very suboptimally. If you are going to parallel strings where one will be heavily shaded and the other will not, you will get better results with individual MPPT rather than multiple strings in parallel to one.
I would not underspec your MPPT based on shaded assumptions. Size for max rated output.