Single-family house – new construction project from day one - and the planning begins

10.5 kWp is unfavorable.
Make it 9.9 or 12+.
However, I do not know if these standard data also apply to KfW40+ photovoltaic systems limited to 60% feed-in.

Thank you for your feedback. I will try to respond to the individual points:

- Construction power/-water 5k not 1k

I have also read that more often now. 5k is pretty steep, but I think I will still increase it to 3k.

- House connection 11k not 6k

That is the experience value from our general contractor who has already built a house in this new development area. Also, there is no gas connection in our new development area...

- Furniture/lamps 6k instead of 2k, although we already had a furnished house before
- Exterior work 50k instead of 25k

The 2k are initially only for the lamps. We have enough furniture and will supplement it selectively from the cash flow after moving in.

Exterior work 50k? We will not fence anything but plant a hedge. We will probably do the paving and terraces ourselves.

- Earthworks 20k for a house with cellar instead of 40k

We have about 720 m² and a slight slope (between the highest and lowest point of the plot there is a 2.5m gradient). The plot is supposed to be fully modeled as a plateau. Also, due to a presumably high groundwater level, drainage might be necessary. Therefore, we have initially set 30k + 10k safety buffer here.

- Kitchen for us 10k, but wishes vary widely here

I think 20k will be tight for us. We have planned a 4.60m long run as well as a kitchen island measuring 2.6m x 1.4m. We would also like a downdraft extractor etc...

Proxon is an air/air heat pump, right? I would strongly advise against it and definitely plan for underfloor heating.

See position "Surcharge for air-water heat pump with indoor unit underfloor heating including controlled residential ventilation." We definitely want to use an air-water heat pump. The general contractor's inquiry to the heating engineer regarding this is ongoing. We had currently planned a total of 40' for the mentioned technology (25' "credit" for the air-air heat pump + 15').

10.5 kWp is unfavorable. Do 9.9 or 12+. However, I don't know if these standard figures also apply to KfW40+ photovoltaic systems limited to 60% feed-in.

We have not decided on that yet and now need to get advice first. We currently have an inquiry with a solar technician running. He also ensures that the system is eligible for funding and prepares an economic viability calculation.

- Construction power/water 5k not 1k

I just thought of something... Did you perhaps build with solid construction and therefore have higher electricity costs (due to longer drying times)?

671 loops, my dear gentlemen's singing club^^ I also have 175 on the slope with a basement living area and garage in the thermal envelope, and the field was already a board with 93k, but I am miles away from that. I am always amazed at how prices have skyrocketed in recent years.

Forget the 5k for the construction power. Our supplier wanted a monthly inspection by an electrician to check if the distributor was still working. My dear singing club, don't ask how much the inspection cost. He charged times, it would have been faster to walk from the neighboring town and check it yourself.

I would also leave the 40k for earthworks. You can gather that quickly. Friends of ours had 20k alone for disposal.
Better to plan for too much than too little. One or two unexpected bills are still coming.