Preparation for future photovoltaic?

You need a second meter if the photovoltaic system has 10 kWp or more power. At 9.8, your meter will be replaced with a forward/reverse meter. From 30 kWp, you need a measuring transformer. So if you want to prepare, first plan how big the system should/can be. Then where the inverter(s) should/can be located. Preferably not a warm place. The strings (here possibly empty conduit) from the panels are laid to the inverters. Number of empty conduits? Number of panels and which system? Then you can continue planning.

practically there can never be too little money for it, as it reduces your expenses.

Well, when building new, you have to have the total amount available... it doesn't help if (if) an investment pays off after 10-12 years.

The modules practically cost nothing anymore

Well, the offers are by no means negligible, but rather still five-figure amounts for new installations. 3 kWp just under five figures, 5 kWp above that. That is no small change for a builder. To what extent photovoltaics amortize quickly with truly precise calculation is by no means that clear. At 3 kWp I save about 400 euros per year... so it definitely does not pay off in 10 years! Many calculations are highly exaggerated.

You need a second meter if the photovoltaic system has 10 kWp or more power

Thanks.

So if you want to make provisions, first plan how big the system should/can be.

Minimally good 3 kWp, maximum 7 kWp, probably rather around 5 kWp. That is certain. More roof area is not available.

where the inverter(s) should/can be installed. Preferably not a warm place

OK, then probably not the attic, but the garage.

Number of panels and which system?

I can’t know which system now. Are there significant differences among the common, cost-effective photovoltaic systems? Can you roughly say, for completely "normal" inexpensive photovoltaic modules of about 5 kWp, how many and how thick cables are needed? Or how many empty conduits would be sensible?

But that then depends on your purchase price. More than €1200 per kWp net is exaggerated even for small systems. For comparison: our offer is €900/kWp all incl. with branded components.

For comparison: our offer is €900/kWp all inclusive with brand components.

That sounds great. I haven't found such a provider in Hamburg yet. I will keep looking... if anyone has recommendations... feel free. For new builds, of course.

I also had the electrician lay thick cables. My photovoltaic installer did not want those but preferred to pull his own cables. So install conduit or better yet build the photovoltaic system right away.

I also find the inverter in the roof very unfavorable: heat/lifespan, higher fire risk, radiation exposure from the AC line that then runs through the house instead of DC.