Slewing Drives Revolutionize Solar Marketplace
September 12, 2016- Slewing drives are revolutionizing the solar marketplace through the economics of land used, lower dollar per watt cost, cost of installation, operation and maintenance (O&M) costs, as well as increased reliability and performance.
In the early stages of the solar industry, the land used for commercial and utility scale solar parks were perfectly level, square plots of land. With this type of land the economics of using one primary mover to tilt a large section of rows is close to, but slightly more expensive, than using a separate slewing drive on every individual row.
The industry has undergone some maturation in the last 10 years, and the land used for new jobs has changed. It is now made up of increasingly rough terrain, odd shapes (parallelograms), and in small pieces rather than one large, continuous plot. The old model of one large prime mover to tilt a large section of rows becomes insanely expensive when the land terrain changes. This is because the cost of that prime mover gets divided over a smaller number of rows. For example, if the perfect land-use model of an antiquated system calls for one prime mover to tilt 30 rows, but only five rows can be driven at a time due to the terrain, the high cost of that prime mover is divided by only five instead of 30. This would cause the cost/watt price of solar to skyrocket. By using KMI slewing drives on every row, the cost/watt remains constant over any size of field, from one to infinity.
When one slewing drive is used on every row, there is an extremely high level of redundancy in the system. By building redundancy into the system, you get a higher level of reliability. This is because the failure of one part cannot take down an entire solar field, but only one row of trackers, at most. This is a very important design philosophy when designing for reliability over a 30 year life span.
Slewing drives have dramatically decreased the purchase costs of components used in solar tracking by combining the structure, bearings, rotation and motion control into one easy to purchase package. This reduces the amount of vendors, logistics, weight, and total costs materials by shared functionality in one beautiful drive.
KMI slewing drives have the lowest field cost of installation compared to any other architecture. First, the weight has been redesigned over time because they are now light enough for a worker to lift and post by hand. Since the slewing drive contains the bearing element, it goes in the place where a bearing would normally be mounted in the field, rather than being mounted to the line in addition to another bearing. The entire slewing drive with bearing, rotation, and motion control is mounted into place in the time it would normally take a bearing to be installed. Once the electrical lines are connected, your solar line is ready to drive, nothing else is required. This means you do not need to purchase any extra brackets, bearings, actuators, or other devices to mount in the line.
Since slewing drives rotate 360˚ (or to a lesser degree +/-60˚ if KMI installs internal stops) there is no special requirement to mount the solar panels higher in elevation off the ground to give the long linear actuators room to work. Linear actuators need a lot of room to translate a linear motion into a rotational one. The further you want to rotate, the higher off the ground you must pay to mount your solar arrays. Therefore, solar arrays can now be mounted 25%+ closer to the ground with slewing drives, which automatically removes 25%+ of the costly steel pier structure required by our customers to mount their arrays in a solar field.
KMI has reduced the O&M costs for solar fields by designing a drive that lasts 30 years, putting it through many levels of strenuous Accelerated Life Cycle Testing, and installing over 650,000 slewing drives in the field.
We’ve gathered data on these units to ensure low maintenance costs over the 30 year life span, like the fact that our drives only require grease periodically. The time period depends on the KMI model and type of lubrication you select from KMI. We manufacture everything from one year re-lubrication intervals to 30 year lifetime models, which require zero maintenance or relubrication.