Mainly that I've yet to follow through on my 5+ year old plan on building a small greenhouse and using solar for water pumping. For most use cases it's a fairly bad "business case" compared to simply buying the power you need. If anything, you would probably be better off setting up a storage sollution to buy power when it's cheap, and then using it when power is expensive, compared to actually setting up power generation yourself.

If I had a good area for them which wasn't some form of rooftop I might have. Rooftop installations are very expensive in Denmark because they are too heavy to be installed without building a lot of support. Even my carport would basically need to be an entirely different structure with a custom foundation to support a roof of solar panels. Which you can absolutely do, but it would be decades before it was worth it.