In recent weeks the benefits of coupling solar with battery storage technology have gone from being a niche topic to the talk of the chattering classes. Thanks to some slick publicity work from Elon Musk and his PR team, tales of the Silicon Valley stalwart’s first forays into the world of stationary storage have found their way on to newspaper front pages the world over. Hype there was aplenty, and only time will tell if Tesla’s bid to revolutionise the solar-plus- storage offer lives up to it. Yet if nothing else, the company’s high-profile launch has shone a light into one of the less glamorous but fundamentally important corners of the storage debate – namely the business models that will enable the technology to pay its way.