Renewables

Solar tree installed around the space used as farmland. Image: Korea Maritime Institute, scientific reports, Creative Commons License CC BY 4.0

Scientists in land-scarce Korea are proposing to use solar trees to build PV installations in forest areas. Although more expensive than conventional ground-mounted facilities, solar plants made of solar trees may capture carbon from forest land and produce energy at the same time.

From pv magazine

Researchers from the Korea Maritime Institute have proposed the use of solar trees to build photovoltaic plants in mountainous forest areas in land-scarce South Korea.

They defined the new concept as forest-photovoltaic and explained that it would both maintain carbon absorption activities under the solar trees and produce solar power on the upper part of forest land.

“Compared to a general flat fixed panel, the solar tree has a higher structure and a stronger support base, increasing construction costs,” they explained. “As the demand for solar trees increases due to the development of new technology, more companies enter the market. Therefore, it is expected that solar trees can be installed at a cost that can compete with the current flat fixed panel in the not-too-distant future.”

Using Google Earth satellite imagery, the Korean group assessed the concept’s operational potential by simulating solar tree installations in a mountainous area at 400 meters above sea level, where there is an operating agrivoltaic plant relying on solar trackers. “The solar power plant was constructed by cutting a mountainous ridge available in the highly elevated plateau into flat land,” they explained. “The solar panels installed on the 3-meter-high structure made a space for farming in the ground. One kind of ginseng, mountain garlic, is being grown in the space at the bottom of solar power facilities.”

The academics used Google Earth 3D to reflect solar tree size and the distance between the trees. As a reference, they considered a 4.8 m × 4.1 m panel with a rated power of 1.2 kW developed by Korea-based module manufacturer Hanwha Q Cells. “The slope distance was measured using the built-in elevation path measurement function in Google Earth Pro to arrange the solar tree at 100 m intervals in the three-dimensional image,” they specified. “The forest area, solar panel, and open space were calculated using the polygon measurement function provided by Google Earth Pro to quantitatively evaluate changes in mountain landscape before and after solar tree installation.”

The researchers performed their analysis with criteria developed by Germany’s Fraunhofer Institute for Solar Energy Systems (ISE) for agrivoltaic projects. One of the important factors they considered is the distance between the solar trees, which is crucial for determining their impact on the surrounding natural environment. They ascertained that, if the trees are installed according to the scale of the 3D image, a considerable number of solar trees could be deployed throughout the 1,100,872-square-meter study area. If too many solar trees are placed in a limited space, however, the solar trees displayed as too small in size, causing significant limitations in terms of visual effect, they noted.

Despite their higher costs compared to conventional PV installations, solar trees may have a strategic advantage as they occupy a much lower amount of land. “The land purchase cost is the most important parameter in calculating LCOE on the solar power plant in South Korea,” the research team said. “Compared to other countries, South Korea ranks third in the world in terms of land price. So, purchasing the land is much higher than the money required to build a solar power plant.” On the other hand, in the South Korean Energy Agency’s most recent renewables auction, the final average price was KRW 143.120 per kWh ($0.11), which shows prices quite above the average prices seen in the world’s largest and most mature solar markets.

“The solar tree has not been popularized yet, so the forest-photovoltaic field has many problems to be solved and is only in its infancy,” the scientists admitted, noting that most major module manufacturers haven’t entered the business yet. “The procedure for the solar tree to be commercialized has to deal with different international standardization and regulation schemes.”

They introduced their concept in the study “Exploring the operational potential of the forest-photovoltaic utilizing the simulated solar tree,” published in scientific reports. “A follow-up study is needed to initiate legally binding international standards for solar trees’ wind and snow load operation,” they concluded.

Author: EMILIANO BELLINI

Cayon Solar’s prefabricated system can can be deployed in series. Image: Canyon Solar

Australian renewable energy start-up Canyon Solar has unveiled a prefabricated solar PV shade structure for commercial carpark applications that it claims can be installed at least three times faster than traditional systems and outcompetes rooftop solar PV on a dollar-per-watt basis.

From pv magazine Australia

Sydney-based manufacturer Canyon Solar has launched a modular solar carport solution for commercial applications that has been specifically designed for rapid installation with company director Will Beaumont claiming the time-saving translates into a significant reduction in site labor requirements and a corresponding cost saving for clients.

“We found with the second prototype that we just finished installing in the Southern Highlands that we’re cracking three times faster installation compared with an in-situ system,” he said. “If you’re deploying it three times faster than an in-situ installation, there is quite a good labor saving in there which we are passing on to the client.

“The labor component is typically 40% of the turnkey costs of the system so it translates to about a 20% cost saving on labor.”

Canyon’s modular solar shade structure is built around individual pods, each measuring 7.5 m long and 2. 6m wide with two pods combined to create a single unit that covers three car park bays. The units can be deployed in series to give shelter to hundreds of vehicles, the manufacturer said.

Each individual pod houses six 660 W bifacial panels from Canadian Solar coupled with multi-string inverters from Sungrow but the structure is designed to easily incorporate components from other manufacturers. The waterproof system can be grid-connected, linked to storage and seamlessly integrates with electric vehicle charging hardware.

The pods and steel support structures are pre-assembled in the factory and delivered to the site where the pods are lifted into place atop the prefabricated columns and rafters. Final electrical connections are completed before the system is commissioned.

“Basically 80% of the work is done before arriving at the site,” Beaumont said. “All the modules on the pods are already installed, they’re wired, the waterproofing system is actually incorporated into the module mounting system so that is already done as well.

“The idea is when you go to install it, all you’re doing is erecting the columns and the rafters are attached to that. You are then basically just using a forklift or a telehandler to lift the pods into place and finishing off the final connections.”

Beaumont, who established Canyon Solar after time spent with C&I solar heavyweight Solgen Energy, said the modular shade structures provide a cost-effective alternative to traditional cloth or membrane-based shade structures and rooftop solar PV installs.

“If you’re trying to sell solar just on solar, carport systems don’t make sense because there’s a lot of extra costs in terms of the foundations, the support structure, all those components,” he said. “But when you look at what a traditional shade cloth costs and what rooftop solar PV costs, which is usually AUD 1.20 ($0.82) per W, when you combine those two budgets, our solar shade structure actually costs less.

“When you subtract what a normal shade structure will cost, our effective solar cost is usually between AUD 1.10 and AUD 1.20 per W. If you are already considering putting shade in the car park, solar shade is actually better than rooftop solar in many cases. And that is from a dollar-per-watt perspective.”

Canyon Solar is yet to secure its first commercial project but Beaumont said the company is in negotiations with “a number of shopping centers and universities” with the first of the installations expected to be completed before the end of the year.

“I’m very optimistic that modular solar shade structures will become a big part of the future solar industry,” he said. “We’ve now hit the point where it is commercially better to install a solar shade structure than a traditional membrane-based shade cloth in most commercial carparks.”

Author: DAVID CARROLL