Visit to Plant

Perennial 'Dichondra' Used for Weed Prevention at 2.6MW Solar Plant

Mat-style installation has greater cost benefit over 20 years

2017/06/19 15:59
Shinichi Kato, Nikkei BP Intelligence Group, CleanTech Institute
Print Page

At the "Exeo Togane Solar Farm," a mega- (large-scale) solar power plant with an output of about 2.6MW in Togane City, Chiba Prefecture, introduced last week, the perennial "dichondra" plant was adopted as a cover plant against weeds (Fig. 1).

Fig. 1: A 2.6MW-output mega-solar plant that Kyowa Exeo developed and operates adopted dichondra mats. (source: Ground Ecology)

Dichondra is a relatively low perennial plant from Latin America that covers the ground surface with creeping stems and numerous, highly dense, small round leaves. In winter, the stems stretching across the ground die like a tropical lawn; however, the plant starts growing on the ground surface again in spring, provided it roots in the ground.

As a result, dichondra prevents other weeds from sprouting and growing. Weeds can sometimes grow between dichondra plants, but the number of weeds is said to be small and so can be removed by hand.

Other than the measure against weeds, the dichondra is apparently expected to keep the temperature of the underneath of solar panels from rising during the hottest months of the year as the green leaves cover the ground.

The power producer Kyowa Exeo Corp adopted dichondra, entrusting the measures against weeds to Ground Ecology (Yachimata City, Chiba Prefecture) as part of the operation and maintenance (O&M) services.

Ground Ecology is a group company of Ground Energy (Yachimata City, Chiba Prefecture), which develops and markets solar power plants. The company grows and ships dichondra. It is even engaged in the management of dichondra, planting it in a mat form, like sod grass, at solar power plants.

Fig. 2: Use at other solar plants. The photos, shot at a solar plant in Yachimata City, Chiba Prefecture, show the plant rooted well and thickly covering the ground. (source: Nikkei BP)

The company has, thus far, reportedly provided dichondra mats to solar power plants at about 20 locations (Fig. 2). Of these locations, the 2.6MW-output plant in Togane City, Chiba Prefecture, is the largest.

Dichondra that Ground Ecology provides is originally from Uruguay and grows up to about 5cm in height. According to Ground Ecology, dichondra is highly tolerant of shade and grows even in areas that are usually shaded under the solar panels.

Around June every year, dichondra produces small flowers and seeds. The stems and leaves grow thicker with the seeds falling on the ground and partly growing.

However, dichondra, originating from Latin America where the climate is different from that in Japan, is said to have poor resistance against cold weather such as frost and snow. Because of this limitation, the northernmost solar plant that adopted dichondra is near Utsunomiya City.