The sun is the ultimate source of energy for life on earth. Harnessing that energy in new ways is a key part of the fight against climate change.

This week, we meet two people who had solar power eureka moments and are doing just that.

One designed a see-through pyramid that produces hot water for low-income countries. The other opened up new space for solar panels by floating them on the water.

We explore these ideas with environment journalist Tom Heap, who joined forces with The Royal Geographical Society to check out the most promising climate change solutions for BBC Radio 4 series ‘39 Ways to Save the Planet’.

Image: Faisal Ghani and his solar water heater.