The problem with this is that solar is unstable and unreliable and may cause your camera to go in and out and be hard on it when the sunlight is weak.
BCPros can definitely run without the battery, but they need the power to be stable. I know they work without the battery because I used one for MONTHS straight with no battery in my house. I had it plugged in by USB cord with no battery and it worked great for months. I am guessing that solar power would just be too weak and inconsistent too often, and then definitely wouldn’t work at night if there was no battery.
How is it different? I didn’t notice the differences, but now I’d like them pointed out to me. 
I asked that question in the AMA And then I added a wishlist about it so that we can show Wyze how much interest there is adding more sounds. Please go to the following wishlist and upvote it and select the main options you think they should add, and any comments for other sound ideas: