How could I use glazing or a conservatory to use the sun to heat my school?

Conservatories are often overlooked in the design of a sustainable building, when in fact they can be the best, most efficient way of heating a building. Conservatories, if positioned correctly, take the thermal energy from the sun and absorb it through glazing. It can be argued that glass is not the best material for holding in heat, but conservatories are usually a secondary structure built on the exterior of a property, so the heat already in the house is not lost. however, heat gained from the glazing can then pass through into the house and warm the house up.
The best orientation for a conservatory is south, so that it gets most of the sun. This could effect the entire orientation of the building. Similar to solar panels, this would only work during the day, and when there is good, direct beams of sun. It is also effected by shading, so if there are any buildings or trees in the way of the sun, the conservatory becomes useless.
As the school is a large multi-story building, a conservatory is not suitable, and it is more suitable for a domestic property. However, glazing could be an appropriate alternative for the school project. If the south facing wall was fully glazed, the amount of thermal energy it could create could heat the entire school, providing the ventilation was set up correctly.
A glazed wall would also allow a lot of light into the building, which typically reaches 6-7 meters into the building. this could also save a lot of energy on lighting.
One issue with a glazed wall is that usually, when it is sunny, it is generally hot. This could mean the glazing is heating a building that needs to be cooled rather than heated. A solution to this is to open the windows and let the warm air back out.
Also, when it is cloudy and the sun is not directly shining on the glazing, a negative effect can occur and heat can be lost through the glazing. this makes the idea of a glazed wall unreliable. It should certainly not be used as a prime source of heat and light in a on the school, but would be a good contributor to heating and lighting the school sustainably.