Application of wattmon for system design and performance improvement of solar PV systems | |
| Author | Thanongsak Kaewsaibuathong |
| Call Number | AIT Thesis no.ET-14-27 |
| Subject(s) | Storage batteries Solar cells--Design and construction Photovoltaic power systems |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Energy |
| Publisher | Asian Institute of Technology |
| Abstract | This research examined the battery charging and discharging characteristic by grid and by solar PV system to understand the conditions for improving the performance of the battery by the user. A study was also conducted to show how an effective load management in solar home system powered by PV using a monitoring and control device (Wattmon) can help in improving the overall performance of the system. The improvements would be in terms of increased useful energy output, increased overall efficiency, etc. Experiments were conducted to study the patterns of battery charging by solar and grid electricity. It was found that the charge efficiency by solar electricity is limited by the PV module efficiency, while the charging efficiency by grid electricity was around 80 %, though only 65 % of charging was observed during the bulk charge state and the remaining charging takes a long time. Therefore, the option to improve charging efficiency in case of a PV system is by using the backup source only during the bulk charge state. Experimental studies on the patterns of battery discharging were conducted at c-rate of C/10, C/14, C/20 and C/30, respectively. It was found that discharge efficiency increases when discharge current is low. This needs effective load management to improve the performance. In addition, the discharge time of battery can be calculated from different state of charge (SOC) conditions and discharge rate by Peukert’s equation and rate of SOC’s equation. This information can help to plan using the energy efficiently. The demonstration of how a Solar Home System (SHS) will continually supply essential load by load management according to SOC was also done. Essential load could be supplied when SOC ranges from 100 % to 30 %, and the non-essential loads could be supplied when SOC ranges from 100 % to 65 %. This way of energy supply to the load by the battery will improve the performance by lower discharge current rate. This load management by knowing the state of charge and the types and needs of the load using the Wattmon monitoring and control device was shown to be effective. However, a backup source is needed in stand-alone solar PV system in order to guaranty the reliability of the system during continued rainy or bad weather conditions. Another demonstration was carried out using excess energy to supply buffer load (the excess energy was produced by the PV system after having charged the battery fully). This will help improve the performance of solar PV system by using direct electricity from PV output to power the buffer load, and thus which can avoid losses, and increasing the useful energy supplied by the PV module. In summary, this research demonstrates how the overall efficiency and reliability of stand-alone solar PV system can be improved by using a monitoring and control device called “Wattmon”. |
| Year | 2014 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Energy Technology (ET) |
| Chairperson(s) | Kumar, Sivanappan |
| Examination Committee(s) | Singh, Jai Govind;Mohanty, Brahmanand; |
| Scholarship Donor(s) | PEA;Asian Institute of Technology Education Cooperation Project;Asian Institute of Technology Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2014 |