Reflective film on large windows on the south side - effective?

Great, big south-facing windows, letting full sun pour in, and then cooling down with air conditioning... what an energetic madness.
In a public building, this would cause a media outcry about poor planning and waste of taxpayers' money.

Why did you even plan for roller shutters and not directly for venetian blinds or shutters?
Sure, retrofitting is possible. Just complicated and expensive.

You can retrofit external blinds as surface-mounted, then you have both.
With air conditioning, at least install blinds inside.
It's not as effective as outside, but better than nothing.
Otherwise, the air conditioning wouldn't be able to cope with the heat under direct sunlight or would have to be completely oversized.

When shading, pay attention to the distance from the glass as well as the position to prevent heat buildup and cracking.

Climate is fine in connection with photovoltaics. Every house built for a family is pure luxury and a waste of space and resources. So everyone should restrain themselves regarding a single-family house.

Yo, if we had planned everything 100% perfectly and correctly, I wouldn't have had to make this post in the forum now... we also know that we planned it wrong... woulda coulda...