Eligible costs for heat pump

I received the notification on Saturday that my system is being subsidized with the maximum 35%. The money will be in the account within 2 weeks. However, I only submitted the heating system.

I did not have to submit proof that I paid the invoice.
The invoice from the heating engineer is sufficient.

Of course, it doesn’t work that fast
First, you submit an application for the funding. Then you receive a confirmation from the office that the funding will be approved if you upload the corresponding proofs online.
The confirmation also includes your online login data for the uploads.
I uploaded the proofs about 1.5 weeks ago and received the confirmation of the funding on Saturday, which will be transferred to my account within the next two weeks.

There you can see how much knowledge the ladies at BAFA have.
Read the information sheet. It is explicitly stated as not eligible for funding.

Is that really so? On page 5 of the leaflet it says: "PVT systems (fully) provided the generated electricity is predominantly used for self-consumption and no remuneration under the Renewable Energy Act is claimed."

Yes, but that means you simply don't receive any compensation. In other words, for the electricity you feed in, you get significantly more through the Renewable Energy Act than what it is actually "traded" for.
I'm not a photovoltaic expert, but I don't think anyone does that. The self-consumption is usually far too low. I don't believe it's cost-effective.