Moving mountains

Extensive earthworks and specially adapted mounting systems allow solar developers to cope with Japan’s hilly terrain. Image: Clenergy.

Solar PV deployment in Japan is continuing to impress, with 11GW connected in 2015, according to figures released in January by GTM Research. The upcoming deregulation of the country’s energy sector, coupled with the government’s pledge in December’s climate talks in Paris that around 30% of its renewable energy will come from solar by 2030, suggests this growth is set to continue. Factor in the 80GW backlog under the feed-in tariff and there’s a lot of business to be had.

However, all the activity scheduled for the future depends on developers overcoming a problem that has plagued the market almost from day one – the issue of land availability.

Over 70% of Japan is mountainous, with the remaining flat land used predominantly for urban development or agriculture. For large-scale solar projects, this presents a significant challenge for developers, who are looking further afield to find new locations and coming up against a range of challenges in the process.

Mounting systems specialist Clenergy has been operating in Japan for almost four years and, according to Charles Ando, vice president for the Asia-Pacific region, the shortage of flat land has led to challenges that come up repeatedly.

“There aren’t many easy sites left now in Japan, only those that are difficult. We have installed over 2,000 projects in Japan and most have had difficulties. Over 90% have had different terrain, ground conditions, snow loads, wind loads, earthquake; you name it,” he says.

Climbing to new heights

With flat land at a premium, Clenergy and other firms like it are turning to Japan’s hills for an answer. While these sites are difficult to build on, they do offer lower land costs, allowing developers to take a more proactive approach to construction.

An obvious use for this extra cash is grading the land to a level base or one with a specified slope, a tactic being used by Pacifico Energy on a number of projects. The company’s largest development to date is being built on Kyushu and according to Nate Franklin, the firm’s country manager in Japan, the 96MW project has involved over five million cubic meters of earthwork.

This method is used widely across the country to ease construction on hilly or mountainous sites, with civil engineering work being carried out on a unique scale.

“One thing that I’ve learned over the last three or four years in Japan is that no other markets are grading this much or doing this much civil work for solar projects. I’ve seen some projects in Europe on hilly sites but no projects in the world are similar to what’s being done in Japan as far as the civil challenges,” Franklin explains.

While it may be difficult to avoid civil works on some level, there are ways to get efficient results. 

“When we first started, a lot of the EPCs were designing projects on a tiered system. You see it sometimes with agriculture where there are a lot of flat tiers that step down a sloped site. That’s really inefficient for solar; the module racks are like building blocks so if you have a lot of breaks in it you have a lot of inefficiencies,” Franklin explains.

“We have a continuous grade on as much of our sites as possible so that there’s not a break in the rows. That’s just one trick that can really increase your capacity,” he adds.

Over time, companies have been able to develop systems allowing them to build on 35% slopes, opening up new possibilities for solar deployment. For example, Clenergy offers a combination of specialised mounting and racking systems for sloping areas, all of which can be altered at the firm’s manufacturing facilities to suit the requirements of each location.

This ability to adapt is key, according to Charles Ando, who says: “You need to be very flexible to change to different solutions.”

Carrying a heavy load

Moving mountains

Tilting panels and snow-blowing equipment are two of the solutions to heavy snowfall. Image: Clenergy.

This flexibility is also needed to tackle the heavy snowfall common in Japan, particularly in Hokkaido where Clenergy has completed a number of projects.

The most widely used method for solving the issue is to tilt the panels to ensure the snow falls unaided. Laying panels at 30 degrees is generally accepted as the most effective way to do this, however with land at a premium this limits how many modules can be installed on any one site. 

While it is difficult to overcome this, stopping the snow from affecting power generation remains key, with a number of techniques being implemented to tackle the problem. Pacifico Energy is testing new machines to blow the snow from the panels into the gap underneath the row in front, while Clenergy ensures that as many of its sites as possible are located near a reservoir or waterway to allow snow to be removed quickly.

A different angle of approach

While the use of hillside developments is expected to grow as new innovations emerge, there are a number of other alternatives to deal with Japan’s land constraints.

Serving as an abiding legacy of the boom years, the country’s obsession with golf led to the construction of many courses across the country. A large number of these have now fallen into disuse, with large-scale developers taking advantage. Three of Pacifico Energy’s four sites currently under construction are on former golf course sites and, as Nate Franklin explains, the nature of these courses suits solar down to the ground.

“Japan just overbuilt golf courses during the boom, which was a great combination when solar came. They make sense because at least the fairways are somewhat flat and so there’s already been some earthwork done and trenches that have been put in that you can utilise,” Frankin says.

“When you’re talking big projects of 20MW and above, I think anything that was flat and usable got done at the very beginning. We haven’t seen a flat, easy-to-develop site for about two years, at any price. Golf courses are about as good as it gets.”

While the location of some courses can present difficulties in reaching transmission lines for interconnection, they remain a popular choice for solar developers. However, many are now looking to avoid the issue of land scarcity altogether by looking to Japan’s waters.

Riding the waves

Floating PV systems are considered by many to be an ideal solution to Japan’s lack of available land, with the country’s agricultural traditions coming into play. While re-zoning of farmland is difficult to achieve, the nation’s historic use of irrigation ponds has left a number of water bodies available for solar installations.

Harold Meurisse, international sales manager for Ciel et Terre, the French firm that specialises in floating PV, claims increasing success is down to the suitability of floating systems in the Japanese market.

“Land in Japan is lacking, especially for 20-25 years for the purpose of energy. If you use unused dead spaces, you solve this equation. Being on water also removes the issue of earthquake codes which bring a lot of problems as they require foundation or civil engineering works,” he says.

Solar on water also offers higher levels of generation thanks to the cooling effect of the water, while the installations avoid the high costs of land and even reduce surface evaporation and algae growth.

Despite these benefits, floating solutions present their own issues. As it embarks on a 13.7MW floating installation (see case study, next page), Kyocera tells PV Tech Power that the systems often present unique challenges. These include making the solar panel and wiring materials waterproof; engineering the system to comply with relevant environmental regulations; and ensuring the system does not corrode over time. Special permits are also typically required which can vary from region to region. 

The area often requiring the most attention is anchoring, as this determines how the floatation devices are secured against the wind and other factors. As Meurisse explains, Ciel et Terre has gone to great lengths to ensure this aspect of its systems has been addressed during development.

“We have conducted lab tests and determined the exact maximum loads that would be applied on the platform and their diffusions. From there we computed an anchoring tool that determines precisely the number of anchoring points needed and each tonnage,” he says.

Cemil Seber, director of product marketing and development at REC Group, claims nothing about floating solar makes the technology “uninvestible” and that its use will grow assuming further developments are made.

“I think that the most important thing is to see how this market develops considering the advantages that solar PV offers on water because of the space issue. The jury is still out on how large the market is going to be. The interest in this is reasonably high, but having said that we need to think about salt water solutions,” he says.

Before floating systems can be rolled out on the open sea, issues around salt water degradation will need to be solved, as will security. Closed lakes or reservoirs provide an element of control in terms of both O&M services and general security of an installation; this cannot be said of open water.

Despite these questions, Seber expects to see saltwater solutions by 2017, with work already underway to improve the durability of solar panels. This development could also address a consequence of the growing success of floating PV: eventually Japan’s inland water bodies could become as rare as its flat land.

With the Japanese solar market set to benefit from April’s deregulation process, as well as the possible introduction of an auction process for large-scale solar projects in 2017, the availability of sites for solar development is likely to only get more critical. The importance of alternatives like mountainous development and the growing trend for use of reclaimed land and floating systems will only increase as a result, and could set Japan up to grow even more solar deployment.

This article appears in the latest issue of PV Tech Power. To read the publication in full click here.

Floating solar goes large

Moving mountains

Kyocera’s 13.7MW floating PV array is expected to become the largest in Japan and the world. Image: Kyocera.

Kyocera has begun construction on what could be the world’s largest floating solar installation. The 13.7MW plant is being built at the Yamakura Dam on the Chiba prefecture and is expected to be completed by March 2018. The plant will incorporate around 51,000 Kyocera modules installed over a fresh water surface area of 180,000 square metres. Floating structures are expected to be supplied by Ciel et Terre, which Kyocera says it has chosen in the past due to the firm’s floating platforms being 100% recyclable and made of high-density polyethylene that can withstand ultraviolet rays and corrosion.

Speaking to PV Tech Power about the project, Kazuhiro Nakamura of Kyocera’s Corporate Solar Energy Group, says: “The installation area is very broad because of its large scale. As ground conditions at the bottom of the reservoir are uneven, the project requires know-how on the anchoring method and the number of anchors.  “For this plant, we proposed anchoring the floating platforms to the bottom of the reservoir rather than to the dam body because the latter method entailed multiple concerns.”

Kyocera began working on floating installations due to land constraints for new large-scale PV development in Japan. Its latest project could showcase the scale at which floating solar can be delivered, with even larger projects expected to follow. A Ciel & Terre representative recently told PV Tech Power that the company is developing a 100MWp floating project in South America, but was unable to give further details.

Tags: japan, mounting, floating pv, kyocera, clenergy, system design

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