You really don't need micro-inverters. Shading is a big problem with the value of solar entirely. How bad is it? enough to cover a few modules for many hours? One hour?
I suppose shading is primarily a problem with low sun in the winter but not in the summer?
I want to show you how to use multi-MPPT string inverters for a similar benefit. If you have two arrays you can get two smaller inverters. I use PowerOne Aurora inverters. Each has two MPPT controllers within each. I have 32 modules making up two arrays (both facing South in the northern hemisphere). In your case, your two arrays could be mounted on separate roof angles, using two 3.6 inverters, you could endure shading if wiring was done such that the lower modules and upper modules in each array plugged into each separate MPPT controller in each inverter. The price would be roughly the same or lower than micro-inverters.
Once you have shading over a small part of all the lower level modules, neither micro-inverter nor string inverter is going to win-out. The group of cells will just produce a lowly amount. You might get a few more Wh a day with micro-inverters as the early part of the shading comes in. But that is pennies per day.
Micro-inverters do not really "draw in the sun" when shaded. they produce very little of course when the module is obscured by shade from trees.
Talk to a local installer who can show the variations between installation methods. A 290W or 300W module can perhaps fully produce using a string inverter during peak sun but would be clipped at 250W with some of the micro-inverters. Except for the PowerOne 300W micro-inverter.
My system is much like this:
XXXXXXXX - - inverter 1 mppt 1 \ .
YYYYYYYY - - inverter 1 mppt 2 / \ ....... LINE OUT
XXXXXXXX - - inverter 2 mppt 1 \ ./
YYYYYYYY - - inverter 2 mppt 2 /
If Module set Y on either inverter is shaded, the X line of modules is producing fully and the minor output from Y is still collected. Unlike a single inverter with one large input and merged strings.
I suppose shading is primarily a problem with low sun in the winter but not in the summer?
I want to show you how to use multi-MPPT string inverters for a similar benefit. If you have two arrays you can get two smaller inverters. I use PowerOne Aurora inverters. Each has two MPPT controllers within each. I have 32 modules making up two arrays (both facing South in the northern hemisphere). In your case, your two arrays could be mounted on separate roof angles, using two 3.6 inverters, you could endure shading if wiring was done such that the lower modules and upper modules in each array plugged into each separate MPPT controller in each inverter. The price would be roughly the same or lower than micro-inverters.
Once you have shading over a small part of all the lower level modules, neither micro-inverter nor string inverter is going to win-out. The group of cells will just produce a lowly amount. You might get a few more Wh a day with micro-inverters as the early part of the shading comes in. But that is pennies per day.
Micro-inverters do not really "draw in the sun" when shaded. they produce very little of course when the module is obscured by shade from trees.
Talk to a local installer who can show the variations between installation methods. A 290W or 300W module can perhaps fully produce using a string inverter during peak sun but would be clipped at 250W with some of the micro-inverters. Except for the PowerOne 300W micro-inverter.
My system is much like this:
XXXXXXXX - - inverter 1 mppt 1 \ .
YYYYYYYY - - inverter 1 mppt 2 / \ ....... LINE OUT
XXXXXXXX - - inverter 2 mppt 1 \ ./
YYYYYYYY - - inverter 2 mppt 2 /
If Module set Y on either inverter is shaded, the X line of modules is producing fully and the minor output from Y is still collected. Unlike a single inverter with one large input and merged strings.
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