Patent ID: 12231079

DETAILED DESCRIPTION

The present disclosure is directed to systems and methods for solar tracker control. Though described generally herein in the context of a solar tracking apparatus that utilizes both a photovoltaic (solar) panel and a battery to provide energy to drive a motor that rotates the tracker assembly, the systems, schematics, and algorithms described herein in any situation where there is solar energy being converted to electrical energy. In particular the systems and algorithms of the present disclosure are useful where there is a solar tracker having a portion of its surface area shaded. A further context for the present disclosure is in the area of a solar farm which is connected to a large power grid and may be associated with large battery banks that can be used to provide power to the grid when the solar panels are unable to meet demand. Commonly owned U.S. Pat. Pub. 2017/0288184 entitled “Standard energy storage container platform,” filed Mar. 31, 2017 and teaches a battery container and U.S. patent application Ser. No. 15/872,071 entitled “Direct Current Battery String Aggregator for Standard Energy Storage Enclosure Platform,” teaches a controller and system for connecting a battery and photovoltaic system to an energy grid. Both references are incorporated herein by reference.

FIG.1depicts a solar tracker system10which is commonly deployed as part of a larger array. Each tracker10includes a plurality of photovoltaic panels12(solar panels). A motor14drives a shaft15, to which the solar panels12are affixed. By driving the shaft14, the solar panels12are maintained at a proper angle to the sun to ensure maximum electrical power generation. The shaft15is suspended between the motor14and a swinging or rotating mount16. Both the motor14and the rotating mounts16are supported on posts18.

FIG.2depicts the area of the tracker system10near the motor14. The tracker system10is located in proximity to the motor14and supported by the shaft15. Either suspended from the underside of the shaft15or mounted to the post18is a box22. The box22houses a battery24, for example a lithium ion (Li-ion) battery, and a controller26. The controller26provides input to the motor14regarding whether to drive and how far to drive the shaft15to enable the panels12to track the sun and moves together with the solar panel12angle.

FIG.3depicts a schematic of tracker level string combining and monitoring in accordance with the present disclosure. In a larger PV array, individual solar panels12ofFIG.1, are connected in series (e.g., positive to negative). This series connection of solar panels12is called a PV string20. Power is communicated electrically from each string20individually to the controller26. Thus, individual currents of each of the PV strings20can be monitored. For example, this monitoring may also be used for over-current protection, solar panel12maintenance, for a tracking algorithm to increase PV plant yield, and/or detection of south-north shading in addition to east-west shading. The controller26may then output the sum of the power as a single pair of DC cable to an inverter or to next level combining.

An example of the controller26can be seen inFIG.4andFIG.5. The controller26includes a control region28which houses a communications module30(e.g., Zigbee, Wi-fi, Bluetooth®, etc.), an inclinometer32, and a main controller (MCU)34. The main controller34communicates with a power supply36, which provides power to the controller26, and with a motor drive controller40, which controls the driving of the motor14. As depicted inFIG.4, the PV strings20provide electricity to the power supply36, which at the discretion of the main controller34is either directed to the battery24for charging, to a boost converter38for application to the motor14to actually cause the motor14to be driven, and/or to an inverter. The main controller34can also determine, based on the input from the PV strings20, whether the energy being supplied is insufficient to drive the motor14, and can cause the stored energy in the batter24to be utilized for this purpose. The power from each of the individual PV strings20is detected by a current sensing circuit44. The current sensing circuit44measures the individual currents of each PV string20. This measured current is fed into the MCU34which can run a tracker control algorithm for optimizing the power created by the tracker system10.

FIG.6depicts a logic flow for a control algorithm600in accordance with the present disclosure. In one embodiment, each of the PV strings20generates a current. (Block602) Each of the individual PV string20currents are communicated to the MCU34. (Block604) The MCU34utilizes the current sensing circuit ofFIG.5. to measure the plurality of the currents individually. (Block606) An inclinometer32detects and measures the PV tilt angle and communicates this angle to the MCU34. (Block608) The MCU34may use a machine learning algorithm to determine based on the plurality of currents, if any portion of the PV strings are shaded. (Block610) The monitoring of each PV string20current will allow the MCU34to detect both south-north shading in addition to east-west shading.

For training inputs, the machine language algorithm may use, for example, the geographical location of the solar tracker system10, the typical sun location in the sky and strength for that time of day for that day of the year, and typical weather for that location and time of year. The machine learning algorithm can anticipate for that solar tracker system10installation, for that geography, for that time of year what the shading will likely be. The term “machine learning” may include, but is not limited to, neural networks, naive Bayes, nearest neighbors, least squares, means, and support vector regression, among other data science and artificial science techniques. Depending on what portion of the PV strings were determined to be shaded, the tilt angle of the PV strings are changed by commanding the motor drive40ofFIG.4to actuate the motor14. (Block612) Thus allowing the MCU34to detect if any portion was shaded and change tracking accordingly. The MCU34can also determine if any of the PV strings20has a failure and disable that PV string20.

While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Any combination of the above embodiments is also envisioned and is within the scope of the appended claims. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope of the claims appended hereto.