Photovoltaic system offer for our single-family house

We still want to build a carport and probably also install photovoltaic modules there.

Do all the planning beforehand. Unfortunately, it's too easy to make it difficult for yourself later, and retrofitting becomes unnecessarily expensive. (Of course, it's best to build everything at once, but I know that's not always so easy)

Question to the experts (so mainly deliverers, but others are welcome too :p )

We are now probably installing modules on both roof sides (as a reminder: 25° inclination, north / south)

Theoretically, 26 or 27 modules fit (depending on the position of the sanitary vents) on each side. The model is:

JinkoSolar solar module Tiger NE HC N-Type sw JKM410N-54HL4-B

Questions about this:

--> North side really fully packed with 27 modules? (I already have an idea of the answer)

--> 1 large inverter or 2 inverters, i.e. one per roof side?

--> if 2 inverters, does the 70% limit apply to both together or per inverter?

--> Do I have to consider anything regarding snow guard grids? Do they have to be higher than "normal" so that the snow does not simply slide over the modules and the grid into the garden?

--> Really fully load the north side with 27 modules? (I already suspect the answer)

tendentially yes, ultimately a matter of price. Additional advantage with N/S: The strong peak on the south side at noon does not constantly trigger the 70% limitation.

--> 1 large inverter or 2 inverters, i.e. one per roof side?

The two roof sides each become one separate string. So you only need one inverter with 2 inputs, which almost every one has.

If 2 inverters, does the 70% limit apply to both together or per inverter?

The 70% always refers to the total generator capacity. The inverter capacities do not matter for the limit.

Do I need to consider anything regarding snow guards? Do they have to be higher than "normal" so that the snow doesn't just slide over the modules and the guard into the garden?

My snow guards just have a bit of distance to the bottom module row. The problem is basically that the snow really stays on the modules until it is completely melted away. Sometimes I wished that a bit would slide off and free up photovoltaic surface :p

the two roof sides each become a separate string. So you only need one inverter with 2 inputs, which almost everyone has.

I guess that won’t be enough. So definitely only one inverter, but 26 modules is probably too much for any current inverter in one string. Therefore, it will probably be two times 13 in parallel on one input. Possible shading should be evenly distributed over all strings.
27 is hard to divide by two, so leave one out (or better yet, add one more. There is room on the smallest shed, or something ;-) ) and then again two times 13.

It’s best to leave out snow guards where possible. Shorten the sewer vents and then build over them. Any carpenter can handle that.

Otherwise, as you suspected, everything is full. 20 kWp is a reasonable system size. Even in bad weather something happens then. Namely about 10% of the maximum output, aka 2 kW. That’s usually enough for a bit of EV charging and easily for a heat pump including basic load. Great!

Thanks to Fuchur and Deliverer! :-)

Regarding the snow guard: I don’t want to omit it. I currently live in a rental apartment with a garden and in winter, snow/ice avalanches crash into the garden with full force again and again. For us humans, maybe not necessarily life-threatening, but potentially life-threatening for my two cats (who also go outside in winter) ;-)

--> But the snow guard is of course nonsense if it is too low and the modules are directly attached. I found the attached photo in another forum; the person wrote that the snow is not caught but simply slides over the modules, which of course is not what should happen.

Regarding the roof layout: in the second attachment you see the south roof layout planned by the solar installer (which I would also like to have 1:1 on the north side). The roof is completely full with 27 modules (it’s not a huge roof, after all). Currently, the snow guard would have no space there at all. Probably the only solution (if you don’t want to omit a whole row of modules) is to make the roof overhang a bit longer... I still have to discuss that with the general contractor.

Thanks for the other tips regarding the inverter and strings!