Case Study

Solar Power System

Solar energy is perhaps the most popular alternative renewable energy source in the world. Both the commercial and private sectors are showing increased interest in solar power generation.

The main attractive features of the solar power system are:

- renewable energy, no fuel required,
- high reliability,
- easy installation and the modularity of system,
- no moving parts,
- possibility of decentralization of generators,
- simplicity of the system, ease of maintenance, &
- low running cost.

System Requirement:

The Erb West field and Tembungo offshore platform located in South China Sea off the coast of Sabah consists of integrated production,processing and well head platform which requires uninterrupted continuous supply for the instruments. The Solar Power System was designed by Swift Energy to replace the existing system produce continuous output of 24Vdc to supply the instrument loads in 8 hours/day. The daily consumption is about 208W. A General alarm has to connect to the client’s SCADA system to report the failure of the system.

The Challenge:

The Solar Power System had to fit the existing space allocated which was the main constraint for the new system. An extended platform is required to ensure the solar panel receive the maximum sunlight and avoid the collision between the new solar panel and the existing. Total of 10 units of solar panels with size of 2550 x 2790mm are compact and fit precisely to the allocated space. The increased safety EEx e battery box managed to fit under the shed of the solar panel to avoid excessive high temperature of battery cells.

Implementation:

The Solar Power System consists of 3 main components:

- solar array panel,
- master controller, &
- battery banks.

Both solar array panel and battery connected to the master controller to supply to the load. During day time, solar panel will supply to the load besides charging the battery. Controller’s main task is to monitor and control the solar power system, protect the battery against overcharge by the solar panel and excessive discharge by the load. Battery bank will only supply to the load during night or periods of low insolation¹. A low voltage pre-warning alarm and load disconnected alarm from master controller will alert the operations team during to any of these alarms.

Detail calculation was carried out to obtain the preliminary size (electrical and physical) of the Solar Power System. Some basic assumptions were made:

- end of cell voltage used for battery is 1.8V per cell and Depth of Discharge shall be 80%,
- battery ageing factor and battery temperature de-rating factor, battery autonomy, &
- solar array panel efficiency, albedo² effect, losses due to dust accumulation and diffuse percentage of insolation.

System Description:

The ATEX certified Zone 1 solar module can charge a 12V battery using a charge regulator. The glass fibre reinforced polyester junction box provides a high quality, dust and watertight IP66 rated housing and fitted with 2 EEx e M25 cable glands to connect the solar array in series and strings to deliver output of 24Vdc or higher in this system. The solar array support is supplied in Stainless Steel 304 or 306 which suitable for offshore application and withstand maximum continuous wind-loading 150km/hr.

Indicator LEDs in front of the master controller indicate the present of the external power supply to the controller, battery charge mode, sub-array disconnected condition, pre-warning low voltage and load disconnect in abnormal situation. The master controller also has a test switch to simulate a high or low battery voltage during maintenance period. The potentiometer is calibrated to the neutral position 2.37V/cell to adjust among both float and boost charge voltage setting.

The Valve Regulated Lead Acid batteries that are installed in an EEx e battery box offer an excellent performance at 932.0Ah to supply to the load during the night or days with no or low solar insolation for 5 days. The lead acid battery permits the daily depth of discharge to 20%. Battery temperature will be continuously monitored through the temperature sensor in the battery box and cut off the battery load if high temperature found.

Benefit:

The Solar power system supplied by Swift Energy is designed, constructed and tested for the best performance. We subject our system to rigorous testing to assure long term reliability and continued power production without any failure. This system is vital to provide continuous supply especially for unmanned and hazardous area. A complete solar solution from design, installation, and commissioning, training and technical support service by us will ensure the system work seamlessly with your utility power supply.

Conclusion:

By integrating a highly reliable solar power system, Erb West field and Tembungo offshore platform has a secure un-interrupted continuous power supply to the Test Separator Metering System. The uninterrupted availability of data transmitted by the metering system is essential to the operations and efficiency in the production.