In a sign that solar-plus-storage is about to go mainstream, Ikea has launched a combo offering in the UK that combines batteries from LG Chem with solar panels from Solarcentury. With a headline claim of a 70% energy bill saving, it’s a boon for smart grid advocates, but perhaps a concern for the smaller and more bespoke solar-plus-storage providers, who might now feel the squeeze from the mighty Ikea. The figures sound like a strong draw for consumers, starting at £3,000 for those who have already installed solar panels. The cheapest solar-plus-storage combo is £5,000. Ikea says that on an installation costing £7,000, a homeowner would pay off the capital investment in around 12-years – at a 6% annual return,…