Every subsidy or grant disrupts markets that have been functioning until then. Photovoltaics are already being significantly promoted by the VAT reduction for everyone. This has developed well and has actually sustainably lowered prices.
The eligible complete packages offered here will hardly bring cost savings, as they are likely to have a price-increasing effect again. Everything has to be done by one company and it will be more expensive anyway. Maybe you can reach the goal faster and cheaper without subsidies. Not necessarily, but it can be.
It is like with the promotion of wallboxes. They suddenly all cost around 900 euros because the eligible amount was also 900 euros. Today, a wallbox no longer costs 300 euros. The promotion at that time was available even without owning an electric car. I myself had approval for 2 wallboxes but did not claim the subsidy. I do not need it at the moment nor in the foreseeable future.
There is usually more frustration than joy about it. I am more in favor of promoting everyone and then preferably a somewhat lower subsidy amount, rather than a few lucky people.