By Alexander Lenfers

Tracking systems are especially suitable tools towards efficiently turning available areas over to power generation. On the other hand, tracking systems cost more than fixed installations. It would make little sense to quote fixed price increases to compare with the price depends firstly on the actual scale and location of the installation, and secondly, on the type of ground the installation is to be installed on. The actual costs of the project will fluctuate, and the additional price component taken by the tracking system within the total budget cost is difficult to gauge. Usually, the additional cost ranges between seven and twenty-five percent; on the other hand, yield may increase by twenty to twenty-five percent on a single-axis tracking system or 30 to 45% on a dual-axis tracking system, depending on the intensity of the sun at the installation’s location; this means that two factors play a role in deciding the quality of the investment─first, the selection of a suitable location, and second, the type of tracking system itself.

Tracking systems such as Kemper KemTRACK ensure maximum efficiency for the operator, despite low initial outlay and servicing costs. Kemper has been applying its many years of experience in metalworking as well as welding and machining to tracking systems for some time; Intelligent solutions such as backtracking, remote-controlled units and very high material stability are good arguments for an investment that will pay off─especially with government subsidies on the decrease in the highly competitive European market.

Acceptance in Europe, Growth in Asia

Cuts in subsidies for solar energy have made market conditions for photovoltaics more difficult in Europe. Feeding solar energy into the grid has lost some of its appeal, cutting ROCE in solar power plant investments. Although the market situation has become more difficult, 2010 saw a record year for photovoltaics in Europe─Germany has shown a continuously high level of acceptance for solar power, and recent incidents in Japanese nuclear power plants are expected to reinforce interest in solar power in Germany by a substantial degree. Intelligent systems for efficient solutions on the ever-shrinking area available will prevail in this new situation.

On the other hand, the photovoltaic markets in the U.S.A., China and India have been showing continuous expansion potentials. These countries still have unused areas available, some sizeable. We have seen increasing investment in the U.S.A. in particular, while China is well on the way to becoming one of the world’s leaders in solar power. Especially the market for photovoltaics in South Korea is a subject to a large dynamic. We observe the construction of large-scale photovoltaic systems in the last years. KEMPER made efforts to raise efficiency of solar parks fits perfectly with the R&D program of the Korean government.

KEMPER is an internationally active company based in Vreden, Germany, located on the German border to the Netherlands. The family company has been investing in innovative technologies since its foundation in 1977 and its business activities include welding and machining, automation and solar power. In addition to its registered office in Vreden, KEMPER has production locations in Germany, Shanghai and Prague, with eight local offices and numerous distributors representing the company across the globe.

KEMPER develops, manufactures and sells safe, stable dual-axis tracking systems for photovoltaic module areas of sixty square meters and more. Having successfully concluded its first solar projects, the company plans to increase its market share in this new business field in the medium term. This year will be seeing KEMPER at five solar power trade fairs for the company to intensify its international orientation, trade fairs such as the recent Ecobuild in London, the U.K. and Ecotec in Athens, Greece.

Dual-Axis Tracking Systems for Photovoltaic Modules

Solar trackers with sturdy construction and manufacturing play a pivotal role in long-term success in a tracked solar installation. The tracking system determines the sun’s position from the location, date and time. It optimizes the module’s surface alignment to capture the sun’s rays. The advantage of this principle is that it works regardless of weather conditions, while avoiding sudden unnecessary and unpredictable movement. The module’s position moves as would a quality watch movement. The tracker moves the module in a way that can be predicted and planned─minute by minute, hour by hour and day by day. The control system supports networking, connection to wind sensors, and remote monitoring. Depending on location, solar power plants will be able to generate up to forty percent more output with our dual-axis tracking systems compared to fixed module designs. The KemTRACK series systems are especially stable against torsion, and are robust and durable; all of the steel parts are hot-dip galvanised. The tracker is still modular in construction─the individual tracker elements can be bolted on, making assembly very easy. In addition, the tracking systems save a lot of space, and shipping them to worldwide destinations in standard containers is fast and inexpensive. The industrial drives are durable, low-maintenance and particularly stable. The dual-axis trackers got completely facelifted for improved control and stability in plants with module surface areas from 70 m2 to 120 m2. The new models come at attractive prices due to largely automated manufacturing using welding robots together with reductions in material consumption. Each tracker centers on a central supporting tube with an integrated elevation drive at its core, optimising force distribution over the tracker’s whole surface area.

Backtracking─Not Only Effective against Shadow

Backtracking prevents collectors shadowing one another in low sun conditions. This feature eliminates shadow from sunrays for the most part, further increasing module yield. The sun is low, and the rays horizontal in the mornings, evenings and in the winter, depending on location. This is where backtracking comes into the picture─backtracking automatically reduces the angle of elevation to prevent the trackers from casting shadows on one other─which is essential in ensuring maximum yield from the sun’s energy. The control system automatically determines when, what time, where and in which period how much deflection is needed, making sure that the tracker returns to an ideal position as soon as the sun reaches a suitable position. Depending on location, this can increase electrical output by more than 40% compared to conventional fixed installations.

While fixed solar installations only reach their maximum yield at midday, solar trackers allow modules to make the best of the sun’s rays at any time of day─an important factor of consideration for operators with regard to power availability, as solar trackers ensure relatively even distribution of solar power throughout the day, allowing operators to predict the amount of power generated and the amount available while giving grid operators a basis to plan on. These benefits are also important in future energy concepts where solar investments are no longer refinanced on feed payments, but need to be negotiated with power supply companies in direct agreements if solar power is to make a significant contribution to a reasonably constant power supply.

Dual Use─Even in Adverse Ground Conditions

Tracking systems contribute towards making the best of the ground area. Gardens and parks, storm water basins, waste water treatment facilities and agricultural areas can still be used for their original purpose in addition to solar power generation. Solar trackers can be mounted on pylons, allowing areas such as parking lots and agricultural areas to be used for solar power. In addition, solar trackers allow rational use of unused side strips next to private properties.

KEMPER has already demonstrated how solar energy can even be harvested on areas that do not seem to be highly suited to efficient solar power in a solar park in Weiterstadt near Frankfurt am Main, Germany. At twenty-two thousand square meters, the storm water basin also hosts a solar park with sixty solar trackers in an installation that is unique in Germany. What makes this installation so extraordinary is that the KemTRACK 60 trackers used do without foundations in the earth, and the drives, control electronics and cabling are mounted a few meters above grade; the storm water basin can be flooded without causing any operational issues.

Realized together with the municipal government, the aim of the project was to boost the municipality’s finances by supplying electricity. The trackers ensure significantly higher power output compared to fixed module installations, and the photovoltaic area totalling 3,600 square meters is planned to generate around 565,000 kilowatt hours per annum. This represents a yield of €180,500 while reducing carbon dioxide emissions by around 396 tons and providing power for around a hundred and twenty-five families─a showcase in efficient combined area utilisation. Disused refuse tips, parking lots and waste water treatment plants are also suitable candidates in addition to storm water basins for solar power without causing any disruption to the area’s original use. Other options for tracking systems for PV modules are showcased at our company’s own demonstration solar park based at our headquarters, with twenty KemTRACK trackers on an area that used to belong to a waste water treatment plant.

Foundations Above or Below Grade

Solid foundations are essential for smooth operations on adverse ground conditions─classical concrete foundations are usually used, especially in smaller projects. The tracker is mounted onto these foundations that are either below grade, or, depending on ground conditions, above grade. The tracker pylon is lowered directly into the foundation, or is bolted onto threaded posts.

First, an assessment is needed to clarify ground conditions and design the foundation for the tracker in drilled and piled foundations. A steel member is turned into a drilled foundation; the member is somewhat wider at the top to allow the tracker pylon to be concreted in. In piled foundations, a drilled hole is filled up with concrete, and the tracker pylon is lowered into the hole or bolted onto threaded posts. Either option is highly suitable for large-scale solar projects, as the foundations are less expensive and time-consuming to lay compared to classical concrete foundations.

Tracking systems mounted onto a central pylon present a wealth of additional benefits─not only in additional yield compared to fixed systems, but also in terms of evenness in power generation at almost full capacity from morning to evening and preventive safety protection in modules and inverters.

Internationalizing Activities─Market Opportunities

KEMPER continues to see favorable market potential in tracking systems. Once the general political conditions apply, there are many options in using classical areas or dual use such as in waste water treatment installations, parking lots, and industrial sites. We have been addressing increased demand in Greece and Israel, but we have also been looking into new markets such as in the U.K. On the technological side, KEMPER sees a trend towards project-specific solutions with the benefit that we at KEMPER provide our customers with development, engineering and manufacturing from a one-stop shop. This applies to steel structures and project-specific control functions. Apart from that, there has been a trend towards systems of eighty square meters and more, systems that can still be assembled with plannable machine deployment. We are to present a new KemTRACK series and extending our range of monitoring functionality in the year 2011. The new models come at attractive prices due to largely automated manufacturing using welding robots together with reductions in material consumption. Each tracker centres on a central supporting tube with an integrated elevation drive at its core, optimizing force distribution over the tracker’s whole surface area.

Alexander Lenfers is COO of Kemper Solar GmbH (www.kemper-solar.eu).