Photo Credit: SolarReserve
If Nelson Mandela were alive today, he would be proud of the rapid growth of solar power in his beloved South Africa. It’s been nearly a year since he passed, and during that time, several hundred megawatts' worth of photovoltaic projects have moved from the development pipeline to actively powering the country's strapped national grid. The latest South African solar farm to go on-line is Jasper, located on former grazing lands in a remote area outside the infamous mining town of Kimberley in Northern Cape province. At 75 megawatts (AC), the plant ranks as the largest in Africa -- for now.
Jasper’s co-developer, SolarReserve, may be better known for its concentrating solar power (CSP) tower and molten salt storage technologies, but the Santa Monica, Calif.-based firm now has 246 megawatts (peak) of completed PV generation assets (the other two being the 75-megawatt Letsatsi and Lesedi sites) operating in South Africa. Among the equity investors who helped pony up the $260 million in financing for Jasper is Google, which made its first renewable investment in Africa via the project. Jasper, which enjoys a twenty-year power-purchase agreement with South African national utility Eskom, was selected in the second round of bids in May 2012 for the country’s Renewable Energy Independent Power Producer Procurement program.
We reached out to Mary Grikas, VP of communications at SolarReserve, who confirmed some facts and provided extensive additional details about the impressive new site.
An international effort
As has been reported before, Yingli scored the module supply deal for the project (tying a nice bow on top of its World Cup 2010 sponsorship in South Africa). Some 325,480 of the Chinese supplier’s crystalline-silicon panels, which are positioned on fixed-tilt, ground-mounted arrays spreading across 358 acres, power the system. Converting the DC into AC are 39 Ingeteam 2-megawatt (AC) central inverter stations, each of which consist of a pair of 1.019-megawatt units, according to Grikas. The power blocks were assembled in-country by an Ingeteam crew, while the racking and mounting steelwork -- all 4,625 tons of it -- was manufactured and assembled by the local arm of Schletter.
While Spanish multinational engineering group Iberdrola and South African firm Group Five have received accolades as the lead EPC/O&M partners, local content, expertise and elbow grease played a major role in the construction of Jasper.
As many as 800 construction workers combined to provide 1 million person-hours while building the plant. Local subcontractors such as Pule Pula (which installed, tested and commissioned the water main system), R&J Construction (which built the operations and maintenance and storage buildings) and Phambili Basie (which is taking care of grass-cutting and general maintenance) have played key roles. The bridge between the PV plant and the grid came in the form of a new 22-kilovolt/132-kilovolt “Kangaroo” and IPP step-up substation built by Ablon Construction, while Siyavuya strung kilometers of overhead powerlines that connect into an Eskom distribution line, as well as helping with other aspects of the grid tie-in.
When you run the numbers for the plant’s overall megawattage, the 96-megawatt (DC):75-megawatt (AC) derate factor comes in at 0.78, certainly within acceptable parameters compared to other large solar farms. Benefiting from a sun-rich direct normal irradiance of 2,780 kilowatt-hours per square-meter per year, Jasper is expected to generate approximately 182,000 megawatt-hours of electricity annually, which is said to be enough to power up to 80,000 South African households (about 833 homes per megawatt).
Of course, those “enough to power up to X homes” figures are always tricky and somewhat arbitrary, and this statistical bugaboo has been vacillating a bit since the Jasper project was first announced. The number has varied significantly, from the 30,000 stated in earlier press releases to the currently touted ~80,000.
SolarReserve’s Grikas sheds some light. “The problem is that the number varies based on many factors. I think the original number looked at just cities. Homes in rural areas tend to use much less power than those in the cities. So, from Eskom reference material, we calculated the average household in South Africa uses 2.263 megawatt-hours per year. So Jasper would [power] 80,424 houses. In our experience, we’ve seen widely varying quotes as to how many households comparable projects will supply. Sometimes [they are] based on peak power supply, sometimes on energy -- [which is] how we did it, [and] which I think is more accurate.”
Now that the plant is operational, the task falls to Group Five and Iberdrola to take care of the all-important O&M duties. About 50 full-time workers will be conducting the operations and maintenance, according to Grikas. The contract calls for the panels to be cleaned twice a year, or more often if the output performance requires. “SolarReserve South Africa will provide asset management services, including management of the O&M contractor and interface with the investors, Eskom, lenders and other project activities and interfaces,” she adds.
On the other side of the planet and the solar power plant technology spectrum, the 110-megawatt Crescent Dunes CSP-plus-storage project is taking shape in Tonopah, Nevada. “Crescent Dunes is progressing quite well,” relates Grikas. “Construction is 100 percent complete, and commissioning is about 75 percent complete. Over 95 percent of the 10,347 tracking mirrors (heliostats) have been calibrated and are working perfectly to specifications; the balance will be completed in the next ten days. We are also commissioning the receiver and expect to be heating molten salt in the receiver -- capturing and storing the sun’s energy -- by the end of December. First electricity generation is expected in February.”
A pair of factoids stand out when you compare Jasper and Crescent Dunes: the megawatt-hour generation figures. As noted, Jasper is expected to provide about 182,000 megawatt-hours per year. For the somewhat larger (in terms of installed capacity) CSP plant, that figure is significantly more, at about 500,000 megawatt-hours. But what does Crescent Dunes have that Jasper doesn’t?
Hot, molten-salt energy storage. When the sun goes down, that stored-up juice will keep flowing.
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This article was originally published at SolarCurator and is reprinted with permission.