Why don't construction prices go down?

I have seen entire halls full of photovoltaic modules at some solar installers. Including inverters and rails, etc. No one expected such a price collapse. But somehow the companies have to sell their expensively purchased stock. It is also problematic to sell older modules. The performance of the modules keeps improving. Nobody today would put modules with 300 heat pump on the roof anymore. Not even the 400 one does anyone want anymore.

So for 10 EUR each, I would take a few 400 pieces (about 50 or so).

So I can only contribute something about the photovoltaic material costs, since I am commissioning the system myself:
- 20.4 kWp modules (49x415W) - Full Black - €3350
- Inverter (Huawei 17KTL), smart meter and WLAN dongle - €1700
- Mounting rack + cables + small parts - €4400
- Scaffolding for 4 weeks - €4000

Totals €13,450 or €660/kWp.
Obtained offers for 10 kWp + 10 kWh storage were between €25,000 and €28,000.

And registration with the supplier with signature?

Yeah... and how long does something like that take with 2 men? At the neighbor's place, 2 solar technicians were messing around for 2 days for 3-4 kWp. That's 4 man-days... So for 20 kWp with storage, everything included... 12 man-days? If we consider scale effects, the complex tasks occur both times. Whether I commission a machine with 20 kW or 200 kW usually makes little difference in effort. Tackling the photovoltaic panels onto the roof shouldn't be that complex. Take 70 EUR/h x 10 hours x 12 days = 8,400 EUR. So your material plus 8,400 EUR = just under 22,000 EUR. Plus the storage, 3-4,000 EUR = 25-26,000 EUR. Completely fine offers, what are you complaining about? Oh right, the solar technician also provides a warranty and a signature. If your house burns down because of a fault in the photovoltaic system, the insurance only pays if it was installed by a professional company. Whoever builds it themselves gets... exactly... nothing ;)

What would one actually save if all those overpaid sales talkers were left out? ;)

And registration with the supplier including signature?

I would be interested in that too. Meanwhile, there are ready-made kits to order and not that expensive. That would make me consider adding something to the garden shed and carport.