Can a photovoltaic system be extended later on the garage?

Hello everyone,

my girlfriend and I have now decided to realize our construction project with Viebrockhaus. Since we are building with KfW40+, we need a corresponding photovoltaic system on the roof.

Unfortunately, our house is not optimally, but rather poorly oriented.
Rotating the house is not possible (on the one hand, we do not want to, on the other hand, we have to maintain an alignment).

Now we have considered putting the standard modules for KfW 40+ on the roof and then installing an extension on the later built double garage with a flat roof.
Is that even possible? What preparations would need to be made in advance? The double garage will be built by ourselves (unfortunately only after the actual house construction, since the area must first serve as a staging area).
That way we could ensure an optimal orientation.

I would be very grateful for your advice and tips.

Who will plan the system?

How much photovoltaic is planned at all?

If the planning and implementation are ensured, I would install the photovoltaics completely including the garage and have the modules stored for 6 months.

The inverter must be appropriately sized and must be able to handle different orientations, strings, and string lengths.

Alternatively, two autonomous systems, that also works, but may be more expensive. And when storage and so on are added, it gets complicated.

Technically, that is definitely possible. I would lay the supply lines to the garage (or at least prepare the empty conduits). Everything else is actually possible too, when the time comes.

But: for KFW40+, everything that comes after is no longer relevant. So everything already has to comply with the regulations before the garage.

And the other question is: what are you going to do with a solar system on the roof that hardly gets any sun? Do you really want to pay for it just so the house receives the "KFW40+" gold badge?

I could come up with a cheaper tile protection...

It's not about a fundamental discussion on whether photovoltaic modules on the roof are sensible or not... Then those will come out of the woodwork anyway who are completely convinced of their system and think everything else is rubbish. My only concern is whether it is possible to expand such a system and what preparations need to be made in advance...

What kind of cable is a photovoltaic system actually connected with?

2 cores plus grounding, have 3x 25mm empty conduits installed in the garage. One is for electricity in the garage and you can use the other two for other [Schweinereien].

If the retrofit is a done deal, you can have the cables installed directly and not just prepared.

Discuss with your energy consultant whether the delayed commissioning of the photovoltaic system could jeopardize funding.

And remember that mounted modules on single-story buildings can be terribly ugly. Expect resistance from the neighbors. If there are design regulations, check those directly as well.

What kind of impossible roof is it that you don't want/can't cover it?