An American company is revolutionising solar power one dollar at a time.
Know anyone with a solar-powered car? How many solar-powered appliances – besides your calculator – do you use? How many neighbours heat their houses with solar power? Compared to other technologies, monitoring advances in solar power has been like watching paint dry.
But there is hope on the horizon for solar cynics. And in this case the sun is rising in the west, California to be precise. In 2004, Energy Innovations, a daughter company of the Pasadena-based dotcom company, Idealab, plans to release the first of a series of revolutionary solar-powered generators that can directly compete with traditional, non-renewable competitors. No subsidies, no excuses, just clean solar power.
In February last year, Energy Innovations launched a prototype solar dish, dubbed the Sunflower 250, which went against the modern PV orthodoxy of trying to convert the sun’s light into electricity. Instead, engineers focused on using the sun’s heat. A Stirling engine was placed at the focus of the array to produce electricity and hot water. However, as the dish failed to meet the company’s strict cost-efficiency targets, engineers went back to the drawing board.
Their new dish design combines an array of many smaller independent reflectors, known as a heliostat, with a special light collecting PV cell at the focus. The cheaper reflectors mean that the more expensive PV generator can be used without exceeding the cost targets. Heat-based applications for the new heliostat are also being considered in the form of a new and improved Stirling engine (see below).
The heliostat arrays measure roughly two by three metres and can produce 250 peak watts of electricity. A typical household would need six to eight units. Initially, Energy Innovations plans to launch the array, which at the moment carries the unglamorous moniker Sunflower Dual-Axis Tracking Solar Connector, for commercial buildings. ‘Because of their size and construction, they’re ideally suited for warehouse-type buildings with flat roofs, like Wal-Marts,’ says Chief Marketing Officer, Steve Chadima. The investment should pay for itself within three to five years, as compared to seven to ten years for traditional PV panels.
For the home market Energy Innovations is toying with a tube design called the SunPod, which has delivered very promising test results. ‘It works great, but we can’t make the plastic components cheap enough at the moment,’ says Chadima.
According to Chadima, if solar energy is to establish a serious presence in the American market it will have to be as cheap. ‘It’s unfortunate, but we’re junkies for cheap fossil fuel. Green technology is and will remain a small niche market in the US,’ he says. Thus, Energy Innovations’ solar revolution is not so much about reinventing the wheel as making it affordable. ‘We’re not doing a lot of raw science here,’ says Chadima, ‘We’re simply taking existing technologies and trying to make them cost effective.’
Stirling’s engine
The Stirling engine was invented in 1816 – before petrol and diesel motors – by the Scottish preacher Robert Stirling. Stirling wanted a safe alternative to steam engines, which often exploded. His simple solution was to drive a piston up and down by cooling and heating air in an enclosed cylinder. In the 1950s, the Philips corporation came out with a Stirling power generator, but the idea was abandoned due to the advent of low-power transistor. The Stirling engine has always been popular among amateur scientists, but is increasingly finding its way into commercial applications ranging from refrigerators to submarines.
