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Hatz | Putting the right twist on solar parks

Joachim Grunwald

Product Manager Mobile Coolers KTR Germany

Much uncertainty still surrounds the future of the world’s energy mix. The coal phase-out seems to be a done deal and nuclear power is 'clean' but entails risks. Many industrialized nations have set targets for their quota of renewable energies, yet the construction of onshore wind farms is often met with public protests. With renewables in general the question of storage arises. And while solar energy enjoys a high level of acceptance and is convincing from an economic point of view, it too needs to be stored. In sunny regions photovoltaic facilities are able to generate electricity at a cost of EUR 0.02 cents per kWh. And even where less sun shines, solar parks with production costs of less than EUR 0.02 per kWh are feasible and competitive. This has generated positive forecasts, especially as solar capacity worldwide rates at more than 500 GW (as at August 2018) with a trend towards larger solar parks.

Inserting ground screws every 30 seconds

The world's largest solar plant near the United Arab Emirates’ city of Sweihan in the Emirate of Abu Dhabi started operations at the end of June 2019. This comprises approximately 3.2 million solar panels – with a total capacity of 1,177 megawatts – that were installed over 7.8 square kilometres, an area equivalent to around 1,200 football pitches. This enables Sweihan’s Noor Abu Dhabi solar farm to supply 90,000 people with clean electricity. The construction of such a complex begins by installing ground screws that anchor the panels. In Sweihan, this amounted to 627,442.

We have to be able to work quickly and efficiently on construction sites, even under extreme climatic conditions. Especially projects in desert regions, with an outside temperature of almost +50 °C, place the highest demands on our machines.

This task is carried out by using ground screw drivers that achieve cycle times of less than 30 seconds per screw. This speed is important because operators need to start producing electricity as soon as possible after a permit is granted. The Krinner Schraubfundamente GmbH in Strasskirchen in Germany’s Lower Bavaria is considered the inventor of ground screws. Krinner also develops and manufactures compatible mechanical screw drivers – tools that have to work quickly, even where the ground consists of hard rock. Because the machines are used internationally, the drive units have to comply with country-specific directives. And as they often operate in sunny hot regions, effective cooling of the drive is very important.

Ground screw drivers: efficient engine cooling is mandatory

Krinner’s latest KRD 60 PV ground screwdriver, which achieves a maximum torque of 5,500 Nm when installed in a compact space, meets all these requirements. The primary drive for the traction and working hydraulics is, in this case, a Hatz 4H50TIC OPU 55 kW diesel engine with 2-litre displacement that forms a compact unit. 

With this engine configuration all the ancillary units, such as coolers and an electronic control system, are already included. And thanks to downsizing and modern common-rail technology as well as turbocharging, it is compact and lightweight yet very powerful. As a result Hatz makes a positive contribution to keeping machine size and overall weight as low as possible – with maximum performance. A KTR MMC series dual-circuit combined cooler enables high performance engine cooling. This module cools the charge air as well as the engine coolant and ensures that the machine delivers high productivity on a steady basis even when inserting ground screws at a very fast pace under high ambient temperatures.

Apart from sufficient cooling performance, dimensions and weight were vital factors for the development of the cooling system. Specifically with mobile applications the space is limited - that is why every centimetre counts. Weight is another key issue.

Hatz already involved us while developing the engines and provided us with all details about thermal balance, ambient temperatures, volume, dimensions, etc.

A further KTR component is used to connect the flywheel and the central hydraulic pump. A BoWex FLE-PA type flange coupling ensures vibration-free power transmission and ultimately ensures that the new Krinner ground screw drivers are able – even under adverse conditions – to very efficiently deliver the preliminaries for solar park construction with a high level of performance. This can be concurrently understood as a small contribution to today’s energy transition on the road to environmentally friendly energy production.