Can Wonderbag, the electric-free slow cooker credited with saving energy, the environment and livelihoods in the world’s poorest places, help Britons struggling with rising power bills and the cost of living?

“We’ve never been more relevant to everyday life, everywhere. That’s why we’re looking for growth investment for this next move,” says Sarah Collins, chief executive of the non-profit social enterprise that she founded a decade ago in South Africa and which also has a base in…