Smart Solar Power System (Energy Storage Monitoring)

Pao, Jun Ren (2016) Smart Solar Power System (Energy Storage Monitoring). Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

The title of this final year project is smart solar power system (energy storage monitoring). The system consists of solar panels, controller and energy storage (12V lead-acid battery). The reason to implement this system is to ensure the safety and effective ways to charge and prolong the life of the energy storage. Many existing products are not effective enough on managing the converted energy from the solar panel and also there is no energy storage level indicator. The most common controller can only indicate whether the energy storage is fully charged or not. The objective of this project is to provide a battery level display for user for safe and easy usage of the product. The battery level display is done by using a simple voltage divider circuit. The circuit works with a voltage reference zener and tied to this is a string of divider resistor that set several fixed voltage levels. Two resistors form a voltage divider that reduces battery voltage by a factor of 3.A quad comparator compares the several voltages from the two divider. This battery level indicator offers LEDs that light up progressively as the voltage increases. There are power connected (0%), greater than 10.5V (25%), greater than 11.5V (50%), greater than 12.5V (75%) and greater than 13.5V (100%). Besides, with this additional battery level display, the users also monitor the power consumption and the level of energy charged. The total time taken for the battery to be fully charged and discharged can be measured. Futhermore, the implementation of charge controller circuit is carried out. The idea is to disconnect power supply to the lead-acid battery once it is fully charged. This charge controller circuit is connected to the last LED of the battery level indicator circuit. The circuit consist of a transistor that sends a signal to a 12V,10A relay and controls the charging status by opening or closing the connection from power supply to the storage. A HEF4027B dual JK flip-flop is used to hold the state of the relay after disconnecting the charging circuit once it is fully charged so that the relay will not connect back once the battery level drops till 12V. The charging circuit will only connect once it reaches below 10.5V. This ensure that the lead acid battery will not keep on connecting and disconnecting between 13.5V and 12V which are just a small difference.