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.

As PV Expo rolls into Tokyo for its eighth outing this month, it coincides with what has been a pivotal time for solar in Japan. Behind the headlines of explosive growth over the past couple of years, some darker currents have been swirling that have threatened if not to bring the wheels off, then certainly to prompt questions over the longevity of Japan’s solar success story.

PV deployment continues to grow at a remarkable rate. In just under 15 years it has gone from being a niche player, with a little over 1GW installed worldwide, to almost 140GW last year – more than a 10,000% increase. The technology’s onward march looks set to continue well into the future, albeit at a slightly more measured pace, with estimates forecasting as much as 430GW worldwide by 2018.