Latest heterojunction c-Si ‘record breaker’ among Japan’s space and time-saving solar gadgets


A heterojunction c-Si solar cell with a conversion efficiency of 25.1% has been showcased by its maker at an event hosted by the Japanese government to exhibit technological innovations in “new energy”.

The government’s New Energy and Industrial Technology Development Organisation (NEDO) this week held a three-day “debriefing” where companies brought innovative products developed during Japan’s 2015 fiscal year, which ended in April. In Japan, clean energy is often referred to as “new” as well as by the term “renewable”. Products were shown off in the areas of solar, renewable or energy efficient heating, biomass, system interconnection and in marine energy, although solar dominated the numbers by some distance.

Solar industry products shown at the event, which took place from Wednesday until Friday, for the most part appeared to follow a common theme of space optimisation, especially in the ground mount and rooftop sectors, according to a summary of the event on the NEDO website.

In addition to the presentation of the 25.1%-efficient cell, which was created by a branch of Japanese chemicals manufacturer Kaneka Corporation in collaboration with NEDO, the products demonstrated included low cost tracking systems for installations on agricultural land, lightweight mounting systems for weak rooftops and specially designed modules for floating PV installations.

Kaneka’s 25.1% c-Si cell

News of Kaneka’s ‘record-breaking’ cell follows recent announcements by Japanese rival Panasonic and US installer SolarCity of record efficiencies measured for PV modules. Kaneka’s new device is a double-sided crystalline silicon cell, with the conversion efficiency verified by Germany’s Fraunhofer ISE.

The company announced in a press release (in Japanese) that it is targeting pilot production for the cells. Kaneka also said that it and NEDO were targeting cost reductions that could take the cost of energy down to Y14 per kWh by 2020 and then halve that to Y7 per kWh by 2030.

Finlay Colville, analyst with Solar Intelligence, said the new cell proved Kaneka had moved quickly in the crystalline silicon PV space, but that the jump to full commercialisation of the heterojunction cell would be the next challenge for the company.

“Previously Kaneka had been one of the early pioneers of amorphous silicon thin-film panels, and it was somewhat surprising a few years back when they announced having R&D activities in the crystalline silicon field. Until now, only Japanese rival solar company Panasonic has been able to commercialise the heterojunction, or HIT, type cell,” Colville said.

“The key question however now is whether Kaneka is simply looking to licence out its know-how, or look for partners to fund volume manufacturing plans across Southeast Asia.”

Innovating towards a grid parity-driven market future

The event took place amid rumours that the country is considering an auction process for future large-scale solar developments. Japan’s utility-scale PV industry, booming in the immediate wake of the feed-in tariff (FiT) being introduced in the summer of 2012, has more or less slowed to a crawl.

Following high profile issues over grid connection and political wrangles over the cost of renewable energy support, it is thought that with a few exceptions, such as projects on water or on otherwise unusable space such as landfill sites, unless projects can be executed at grid parity the utility-scale sector will be severely limited to some 57GW of already FiT-approved projects that have been submitted to Japan’s regional power companies and are forming a queue.

For this reason, the immediate future for PV in what is still one of the world’s top markets looks increasingly likely to focus on rooftops, both commercial and residential, but with an emphasis expected on the latter. As with other markets targeting near-term grid parity, the imminent departure of the FiT by 2020 at the very latest – if not before then – many of those selling into the Japanese market are seeing self-consumption of PV-generated power by households and businesses as the answer to keeping solar economically viable.

Another big change imminent that could alter the landscape is the expected deregulation of the electricity industry next year, with more than 700 new would-be providers already registering an interest in entering a field currently restricted to just 10 players, Japan’s regional power companies, which at present are also responsible for the grid in their own service areas.

At the PV Expo show held towards the beginning of 2015, many industry sources PV Tech spoke to said they expected this deregulation or “unbundling” process to make a significant change and in the case of Canadian Solar CEO Shawn Qu, a significant boost, to the PV industry.  

Meanwhile in a recent interview, Japanese thin-film maker and developer Solar Frontier expressed the opinion that grid parity is not far away for Japan’s residential PV market and even including battery storage in system kits, expects unsubsidised solar to be viable within a “couple of years”.

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