Inverter vs Micro Inventor

[Bob Smith]

Hello

Background:

When using optimizers, there is an inverter and the PV are connected in series on the string(s). The optimizers are installed on the panels that need them.
When using Micro Inverter, each panel has one and there is no need for an inverter. The concept of series or parallel is irrelevant as the output of each panel is 240V 50Hz (please correct me if I am wrong)

Questions:
1) Can we add new panels anytime, anywhere when using micro inverter?
My understanding is that with Inverters, the panels are linked in series on the same string. it can be very difficult to add new panels on that same inverter.

2) Is it easier to mix panels with micro-inverter than with a string inverter?
A string inverter has a max and min voltage for the string. When mixing panels of different dimensions one must ensure that the sum DC max and DC min for each panel does not exist the inverter string. I understand that when using micro inverter. This is irrelevant because each panel (or a group of panels) will have its own inverter (micro). Is that correct? PS: The reason for mixing panels of different dimensions is to maximize the cover.

Thanks

 

[binky]

Hello

Background:

When using optimizers, there is an inverter and the PV are connected in series on the string(s). The optimizers are installed on the panels that need them.
When using Micro Inverter, each panel has one and there is no need for an inverter. The concept of series or parallel is irrelevant as the output of each panel is 240V 50Hz (please correct me if I am wrong)

Questions:
1) Can we add new panels anytime, anywhere when using micro inverter?
My understanding is that with Inverters, the panels are linked in series on the same string. it can be very difficult to add new panels on that same inverter.

yes, 1 panel 1 inverter no string issues just tap into the cabling, assuming cable is man enough to take the extra load. NB with AC on roof you must earth the framework, I've done this with a bond to the AC cabling.

2) Is it easier to mix panels with micro-inverter than with a string inverter?
A string inverter has a max and min voltage for the string. When mixing panels of different dimensions one must ensure that the sum DC max and DC min for each panel does not exist the inverter string. I understand that when using micro inverter. This is irrelevant because each panel (or a group of panels) will have its own inverter (micro). Is that correct? PS: The reason for mixing panels of different dimensions is to maximize the cover.

Thanks

Correct, you can mix and match panels to your hearts content. Mixing panels with a string inverter is a bad idea. The inverters have a preprogrammed power curve for the MPPT which it follows to max power output. If you mix panels you are trying to follow multiple power curves so it can't really optimise the power output properly - it will still work, but efficiency will be compromised, although I'm not sure by how much as I've never really tried it. SMAs opti-tracking, which is their version of shade compensation, works by having wider power curve tracking algorithim. So when you have a shaded panel in a string it can look over a wider tolerance for the optimum power point.

 

[Kot]

Hello

Background:

When using optimizers, there is an inverter and the PV are connected in series on the string(s). The optimizers are installed on the panels that need them.
When using Micro Inverter, each panel has one and there is no need for an inverter. The concept of series or parallel is irrelevant as the output of each panel is 240V 50Hz (please correct me if I am wrong)

Questions:
1) Can we add new panels anytime, anywhere when using micro inverter?
My understanding is that with Inverters, the panels are linked in series on the same string. it can be very difficult to add new panels on that same inverter.

2) Is it easier to mix panels with micro-inverter than with a string inverter?
A string inverter has a max and min voltage for the string. When mixing panels of different dimensions one must ensure that the sum DC max and DC min for each panel does not exist the inverter string. I understand that when using micro inverter. This is irrelevant because each panel (or a group of panels) will have its own inverter (micro). Is that correct? PS: The reason for mixing panels of different dimensions is to maximize the cover.

Thanks

2 quote---The Enphase microinverter family can be paired with 60 cell / 120 half cell, 72 cell / 144 half cell and 96 cell PV modules that match appropriate specifications. Do not connect an Enphase microinverter to a module that the calculator indicates is incompatible. A module should not exceed the maximum input DC voltage of the specific Enphase microinverter model, the datasheet information for which is provided enphase.com/en-uk/support. Doing so may void the warranty. -- end quote


https://www4.enphase.com/en-uk/supp...8.1930161911.1670146801-1516364203.1669055875

 

[Kot]

quote--The Enphase Microinverter models listed in this guide do not require grounding electrode conductors (GEC) or equipment grounding conductors (EGC). The microinverter has a Class II double-insulated rating, which includes ground fault protection (GFP). To support GFP, use only PV modules equipped with DC cables labeled PV Wire or PV Cable.

 

[binky]

quote--The Enphase Microinverter models listed in this guide do not require grounding electrode conductors (GEC) or equipment grounding conductors (EGC). The microinverter has a Class II double-insulated rating, which includes ground fault protection (GFP). To support GFP, use only PV modules equipped with DC cables labeled PV Wire or PV Cable.

You have to consider the cabling for the AC well, and how prone that maybe to damage. I can't remember how the micro-inverters are connected, but you would be wanting to run something like SWA into the roof for the AC cct. I would terminate that into an adaptable box, and take an earth bond from that point to each line of panels (frames)

 

[Bob Smith]

2 quote---The Enphase microinverter family can be paired with 60 cell / 120 half cell, 72 cell / 144 half cell and 96 cell PV modules that match appropriate specifications. Do not connect an Enphase microinverter to a module that the calculator indicates is incompatible. A module should not exceed the maximum input DC voltage of the specific Enphase microinverter model, the datasheet information for which is provided enphase.com/en-uk/support. Doing so may void the warranty. -- end quote


https://www4.enphase.com/en-uk/supp...8.1930161911.1670146801-1516364203.1669055875

HI @Kot Thank you for this.
I should have checked my messages earlier!
I have been spending the morning on enphase website and found your module compatibility link

I also find thes videos instructive
https://www4.enphase.com/en-uk/support/solar-professionals/microinverters

The bottom one is for @binky

 

[binky]

Outdoor grade flex, but not armoured from what I can see, I would bond the frame at the junction box

 

[Bob Smith]

Outdoor grade flex, but not armoured from what I can see, I would bond the frame at the junction box

Do you have some picture/specs I have no idea what you are talking about.

 

[Bob Smith]

2 quote---The Enphase microinverter family can be paired with 60 cell / 120 half cell, 72 cell / 144 half cell and 96 cell PV modules that match appropriate specifications. Do not connect an Enphase microinverter to a module that the calculator indicates is incompatible. A module should not exceed the maximum input DC voltage of the specific Enphase microinverter model, the datasheet information for which is provided enphase.com/en-uk/support. Doing so may void the warranty. -- end quote


https://www4.enphase.com/en-uk/supp...8.1930161911.1670146801-1516364203.1669055875

Came across this one

https://enphase.com/installers/microinverters/calculator
Similar stuff though

 

[binky]

Do you have some picture/specs I have no idea what you are talking about.

Look up SWA cable, Wiska adaptable boxes and H07NR cable, although I think the cable from Enphase is more like a PVC flex.

 

[Kot]

Do you have some picture/specs I have no idea what you are talking about.

Its rubber
H07BQ-F

https://enphase.com/en-gb/download/iq-cable-accessories-data-sheet