Robot with brush, water, wiper tackles solar panel cleaning

Credit: Sinfonia Technology (previously known as Shinko Electric Company)

At large-scale solar plants, keeping the surfaces of solar panels free from dust, sand and bird droppings is not just a matter of finicky housekeeping.

It can be a matter of plant profitability. Dirty panels lower power generation efficiencies.

Bird droppings on panels, for example, block the sunlight.

A Tokyo-based company has a solution. Sinfonia Technology announced late last month that it has developed a robot with camera and sensors that can move autonomously and clean solar panels at large-scale solar power plants.

Sinfonia's robot has a distinction in being "autonomous" in that, rather than tethered to rails, the robot is able to move from panel to panel, to tackle the panels' dirt and debris.

The robot is equipped with scrub brush, wiper and detergent; and also sprinkles water stored in its tank. The robot can work in the dark; it has LEDs, having wavelengths in the infrared range.

Aside from autonomy, another key distinction is that Sinfonia's robot can handle the fact that not all solar panels are alike; the robot is designed to tackle panels that tilt in different ways.

To clean tilted solar panels on a mounting system, the robot can move on a planes tilted at 5-30°. If there is a gap between panels, the robot can go over a gap of 50cm or less and can deal with a height difference of 30cm or less.

The robot is powered by a battery and is capable of wireless data transmission. A tablet can be used to check the robot's status—to check if, for example, it has enough water or to check the battery charge remaining.

Sinfonia Technology, in promoting the benefits of its panel-cleaning robots, also noted cost advantages over using manpower for cleaning panels.

Generally, experts say that, for large-scale solar panel installations, attention to keeping the panels clean makes sense.

Earlier this year, however, a study out of the Jacobs School of Engineering at University of California San Diego, in quantifying losses of electricity output due to dirty solar panels, found panels that hadn't been cleaned, or rained on, for 145 days during a summer drought in California lost on average a little less than 0.05 percent of their overall efficiency per day.

The overall conclusion was, that cleaning the panels often was not worth the cost, according to the study's engineers.

They cautioned, though, that their study focused on smaller systems and that, for very large installations, economies of scale may mean that washing panels was worth it.

Sharp, meanwhile, is another Japan-based company showing interest in devising automatic ways to clean solar panels.

The UK CubeSail: Tackling Space Debris

The first spacecraft designed to do away with itself was unveiled on Friday. It will try out an idea that could stop space getting clogged up with junk orbiting the Earth.

The debris of abandoned spacecraft and satellites is building up in low Earth orbit. This zero-g scrapheap has grown by 40 per cent in the past four years alone, with the US air force now tracking 19,000 orbiting objects larger than 10 centimetres across. And as chunks of debris strike each other, they fragment further – presenting still more threat of collision to working spacecraft.

The diminutive CubeSail craft, measuring 30 by 10 by 10 centimetres and weighing just 3 kilograms, has been designed at the Surrey Space Centre at the University of Surrey in Guildford, UK. It has a solar sail that it can use for propulsion – harnessing the pressure of sunlight, just as a boat's sail harnesses the pressure of the wind – but it can also use the sail as an "orbital brake" to help it de-orbit to a fiery death in the atmosphere.