Power producers and O&M (operation and maintenance) companies are concerned by weeds when operating solar power plants.
If weeds grow higher than solar panels, they shade the panels and reduce the power generation amount. If weeds further grow densely, fire could be caused if sparks are generated from power generation equipment and ignite the weeds once they have died. They could also cause problems if pollen, seeds and insects are scattered to the surrounding areas.
There are no perfect measures against weeds at present. One of the most frequently incorporated methods is their removal by grass cutters. Weeds grow well in hot weather from early summer to late autumn and need to be cut by grass cutters at least two to three times during that time.
The physical load on grass cutter operators is high. If the operations are entrusted to external companies, the cost and problems including damage to the power generation equipment will increase. Many power producers are concerned about positioning of the operations in business plans.
Riding-type grass cutters (Fig. 1) are increasingly being introduced to mega (large-scale) solar power plants as measures to improve the efficiency of weed removal operations.
Unlike operations using conventional grass cutters, the operators do not have to walk around on the site. The operator does not have to support a heavy grass cutter with the shoulder and waist using a belt. The operator simply rides on a 4-wheel vehicle similar to a go-cart and drives around the site. Weeds are cut by rotary blades installed below the seat.
Operators of riding-type grass cutters seem to enjoy the work, judging from their facial expression. Weeds are cut speedily while the operators drive the vehicles navigating tight corners. Riding-type grass cutters also change weed cutting from "hard work" to "entertainment" (Video 1).
Video 1: Cutting at a mega solar power plant in Fukuoka Prefecture. The power producer operates many mega solar power plants in Fukuoka Prefecture and other prefectures and frequently removes weeds by using riding-type grass cutters (source: Nikkei BP)
The operation efficiency improves when the time for weed removal per area is short and the site is large. All the solar power producers that incorporated the riding-type grass cutters say they can no longer return to the conventional methods.
Riding-type grass cutters are widely used by farmers for cutting weeds in fields and orchards. Because of this, the vehicles are normally made by agricultural machine manufacturers. Chikusui Canycom Inc of Ukiha City, Fukuoka Prefecture is one of such companies.