In a dusty yard under a blistering August sun in California, Rover was hard at work, lifting 20-kilogram solar panels off a stack and installing them, one by one, into a concrete track. A few yards away, Rover's companion, Spot, moved along a row of panels, washing away months of grit, then squeegeeing them dry.
But despite the heat and monotony, neither Rover nor Spot broke a sweat or uttered a complaint. They could have kept at it all day.
That is because they are robots, surprisingly low-tech machines that a start-up company called Alion Energy is betting can automate the installation and maintenance of large-scale solar farms.
The company, based in Richmond, California, is ready to use its machines in three projects in the next few months in the US, Saudi Arabia and China. If all goes well, executives expect they can bring the price of solar electricity into line with natural gas by cutting the cost of building and maintaining large solar installations.
In recent years, the solar industry has wrung enormous costs from developing farms, largely through reducing the price of panels by more than 70 per cent since 2008. But with prices about as low as manufacturers say they can go, the industry is turning its attention to finding savings in other areas.
For all that the industry promotes its innovations, the business of mounting panels on the ground has remained largely the same for years, a process adapted from smaller rooftop arrays that use metal racks to hold the panels in position. In an expensive, time-consuming process, workers clear and level the ground, drive in posts and attach and wire the heavy, glass-encased modules. Projects frequently run into delays.
After the panels are installed, it can be expensive to keep them free of dirt or growing vegetation that can block sunlight and reduce their output. That task often falls to crews of workers driving along the rows of panels, which can stretch for kilometres.
Several companies are developing robots to aid in installation or cleaning, including the Swiss outfit Serbot, which makes robots that can wash skyscraper windows as well as clean solar arrays.
Another start-up based in California, QBotix, has developed a robot that controls tracking operations, moving along an array and tilting the panels to follow the sun and maximise their output.
Wasiq Bokhari, the company's chief executive, said getting as much as 40 per cent more electricity out of each panel than in a fixed-tilt system allowed developers to build smaller, cheaper systems to meet their energy production targets.
Alion's installation system is designed to work on uneven ground, cutting down on the need to level fields. First, a machine used to lay footpaths and gutters spits out a long concrete track. Rover, which resembles an industrial warehouse cart on caterpillar tracks, installs the panels and glues them in place. Human workers then wire the panels into the system.
Spot can be controlled with a smartphone and runs on a solar-powered battery. It rolls along the rails beneath the panels, squirting water and passing over them with a spinning brush and a squeegee. It also has a standard hedge trimmer attachment that can cut vegetation from the ground.
The promise of automation is not only to reduce labour costs but also to cut construction time - to 12 weeks from six to eight months in some cases.