Mr. Dong Jianyi shows clearly with the temperature curves in his Chinese passive solar greenhouse vividly what the problem is, basically too much swing of temperatures: too hot during the day and not warm enough during the night. Go to his video here https://www.youtube.com/watch?v=pXPakvPzgpE&t=890s to see the temperature curves. How to solve the problem? Check this video to see why storing the solar heat in thermal mass of water and liquid soap bubble foam is important.
A story about Richard Nelson and his simple and yet unprecedented inventions