There are proposals to use solar panels . . You may know solar panels convert sunlight to voltage and then to electricity however solar panels are expensive . There is the simplest solution for utilizing the sunlight. As today roof is covered using opaque : ( no sunlight ) material. If we use transparent material ( simplest one is glass) and the roof curtain. Sunlight can directly be used . Check the diagram you will be easily convinced it is easier than imagination . You could have contolled windows too. ( Google or Ping it)
Easy to construct
Easy to replace old roof
Cheaper than having sola panels
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