Sir – I would like to add a comment on the excellent letter from the chairman of Sustainable Woodstock, Colin Carritt, concerning domestic solar energy (December 22). To my mind, the framework that is needed is an obligation to be placed on all electricity suppliers to source a specified fraction of their delivered electricity from roof-tops, domestic or industrial. The legally-binding fraction would increase each year up to some realistic value.

The essential point is that the need to change our energy system into a sustainable, as well as a carbon-free one, applies to everyone, and not just to pro-active individuals or community groups.

But there is much more: suppliers would be able to deal readily with replacement of units suffering loss of efficiency, upgrading units as technological improvements occur, the introduction of distributed storage etc, in a way that individuals can’t.

In this scheme, electricity suppliers would locate the sites offering best efficiency, and pay the owners rental for the use of their roof-space.

All the equipment would belong to the electricity suppliers who would handle installation and de-installation (if/when required). Suitable legal frameworks would need to be established, to protect all parties.

Chris Osman, Oxford