The issue of ROC retirement is an interesting one. Most 'green' packages are not green at all - if all ROCs are sold on then users of these packages are actually subsidising the electricity price of non-green tariffs by paying over the odds for the mandatory renewable part. As far as I know, Good Energy and the new British Gas Zero Carbon tariffs are the only ones that retire ROCs. But they sells most: according to the Green Electricity Marketplace, Good Energy retire just 2.1% yet BG retire 12%.

There are other reasons for choosing a green supplier - for example their investment in encouraging people to generate their own renewable energy. It is for this reason that I stick with Good Energy. However, I would very much like them to increase the number of ROCs they retire. Maybe they could let the customer choose how many of their ROCs are retired and pay accordingly?