Defeating the purpose:
“I see you’re admiring my little box,” the Knight said in a friendly tone. “It’s my own invention- to keep clothes and sandwiches in. You see I carry it upside down, so that the rain can’t get in.”
” But the things can get out,” Alice gently remarked. “Do you know that the lid’s open?”
” I didn’t know it,” the Knight said, a shade of vexation passing over his face. ” Then all the things must have fallen out! And the box is no use without them.”
― Lewis Carroll, Through the Looking Glass
A local three-story high-performance house, used for offices, includes photovoltaic (PV) panels on the east-facing section of the roof. The panels are transparent and provide plenty of natural light to the “living” attic underneath. However, it turns out that the attic cannot be occupied because due to the huge amount of glass facing the sky, it can become too cold or too hot depending on the day of the year or the hour of the day; in addition, to causing glare. So after more than ten years after construction, the attic cannot be occupied, and remains empty!
The Figure below shows air and operative temperatures from January to March of 2015. Large daily temperature variations are appreciated (far out of the comfort zone in gray), particularly in the clear sunny days/nights. It can be noticed that the temperature fluctuations are more pronounced in the operative temperature as it gets colder when cold (due to a cold PV glass) and warmer when hot (due to a hot PV glass).
The house is heated and cooled with a forced-air system that does not seem to cope with the attic thermal demands. The air handler services two zones, each controlled by a thermostat: zone one is the ground floor, and zone two is the second floor and the attic. However, the thermostat located in zone two is in the second floor, so it does not know what is happening in the attic.
So the transparent “PV-integrated” glass panels do provide free electricity, but seem to defeat their purpose, and as a result the attic is inhabitable. In this case, should they be called “PV-fragmented”?