Design and realization of an efficient pay as you go solar module equipped with online maintenance for the energy supply of a dwelling

. According to 2020 World Bank report, just 64.7% of Cameroon’s population have access to electricity with only 80% of the supply concentrated in urban areas having persistent power outages throughout the country especially in the dry season. From these statistics, individuals are now hocking up to alternative renewable energy sources. In this work we propose a Pay As You Go (PAYG) solar module as solution. The objectives of this work are; improve energy access in off grid areas, design an electronic system that can monitor and control the system, ensure sustainability and affordability by an average Cameroonian. A 13 watts energy system is designed around an Arduino board associated with other modules. A XoJo desktop platform is used to monitor and control the solar module. The user can recharge the module by sending the SMS “RECHARGE PAYG” and the platform will respond by sending a guide to follow. If this is done, the platform automatically initiates the activation. If successful the owner will receive a Short Message Service (SMS) confirming the activation, otherwise an activation code is sent to manually activate the system using the keypad. Payments are done through mobile money operations. In case there is a fault on the system, based on the received information, the owner will be instructed on what to do for maintenance. Thereafter, they will be a feedback indicating the fault has been eliminated.


Introduction
Power generation is a major problem in many developing countries.Due to increase in energy demand both from the industrial and commercial sectors, energy demand reaches its peak this is revealed by a world bank 2020 [1], energy report which shows that just 64.7% of the Cameroonian people have access to electricity.80% of the grid energy is concentrated in the urban areas and is accompanied by persistent power outages during the dry season, when water levels are low.As a result, the population is tilting towards other sources of energy production such as mini hydro power generation and other renewable energy.Amongst the other sources of energy production, solar has been proven to be reliable as compared to other renewable sources.Though, investment in the solar sector is initially high.Technologies have been developed to reduce the cost of solar modules and hence making them affordable.

Objective.
The purpose of this study is to design and realize an effective PAYG (Pay As You Go) solar module with real time monitory and online maintenance.

Significance of the project
This study is a step to uncover the myths attached to the economy of our country, to adapt and join the technological developmental trends, and open up an avenue for further research in this domain.The experimental module developed can be adapted to fight against the problem of shortage of electrical energy.Our system seeks to enable and build evidence for the shared value of partnerships between the mobile industry and utility service providers in order to improve energy services through PAYG models.Through most of our studies and reports, we have shared significant evidence of the role that mobile technology can play a vital role in improving essential energy services for low-income population.

Literature review
Solar energy has been used by mankind for thousands of years.For instance, 2000 years ago solar installations were built to extract salt from seawater.Today, harnessing the sun's energy includes a diverse set of technologies that range from simple sun drying of crops to direct generation of electricity using photovoltaic cells.To increase energy access, today PV modules are integrated into systems designed for specific applications.Furthermore, the use of Internet of Things has equally contributed a mile stone to energy access as in some countries like Kenya and Uganda [2][3][4][5][6].

Materials
The following materials were used to realize this project: the Arduino UNO, LCD screen, sensors (voltage and current sensors), SIM800L module, keypad and XoJo platform, Solar panel, the charge controller, the battery, Cables, Inverter.

Methods.
The research methods used in this project are the experimental method and secondary sources Corresponding author: kazealoyem@yahoo.fr .
Fig. 1 Synoptic diagram of the system Fig. 1 shows the synoptic diagram for the system.The sensors communicate with the arduino using it analog pins.The XoJo platform is installed on a computer to which the GSM (global system for mobile communication) module is connected.The another identical GSM module is installed on the system.The GSM is design using the SIM800L.This module is responsible for the communication between the platform and the module installed at the user end.The other modules are sensory and control units responsible for picking up the signals and sending to the platform for interpretation.The data received from the sensors is been process by the Arduino and send to the XoJo platform using the SIM800L module.The SIM800L communicate with the arduino via serial protocol.The detailed flow chart for the system is as shown in Fig 2.

Functioning of the system
Once the system is powered and initialized it reads the data from the current, voltage and weather sensors which it sent to the XoJo desktop application.The system further checks if there is any system malpractice, if there is any then the module will turn off and send a notification message to the service provider.When the module is off, it can only be reactivated from the platform.If the user want to recharge his module, he/she can do this just by typing "RECHARGE PAYG" and our platform will respond with a user guide.If that is done, the plate form automatically initiate the activation of the module if successful the owner will receive a confirmation SMS otherwise an activation code is send the owner to perform the process manually on the module using the keypad.

Calculations
After explaining the role and function of the various components found in the system, we shall in this section, focus on the dimensioning of the components used in the realization of the prototype of the PAYG solar module.

Results
Here we present the results obtained with the module.The developed platform is used to control and monitor the system based on the information received from the sensors incorporated in the system.The platform does so through the following; registration, activation, generation of bills, payment through mobile money and user disconnect.An example of a mobile money transaction with the system is presented.

Mobile money transactions with the platform
When the module is switched on, the system first of all establishes network connectivity between the system and the network service provider.As shown in Fig 6.

Fig. 6. Testing of GSM communication on XoJo desktop application
When the connection is successful, they following information is then displayed on the XoJo platform: "Hello, arduino is talking" From which the following is obtain indicating that the system is ready for any transaction."OK" +CUSD: (0-2) OK OK OK To recharge the system, the user needs to send the following the service provider number (the platform module):

PAYG#amount#module_serial_number(the installed sim card in the module)#
The system checks whether the format is respected, if not the following message is sent to the customer "Sorry!format not respected" When the format is respected, the system will proceed with the transaction.
Let us consider the following information sent to the service provider number: PAYG#100#672529652# The module with serial number 672529652needs to the recharged with100 Frs.

Conclusion and recommendation.
In this titled design and realization of an efficient pay as you go solar module equipped with online maintenance for the energy supply of a dwelling, had as objective to increase access to electrical energy in off grid areas in Cameroon using energy from the sun.The system was sized for a typical load demand of 13W made up of two 5W LED bulbs and a phone charger port of 3W with a battery autonomy of 1 day.The activation process is done over available GSM network using mobile money transactions.The monitoring and control of the system, is achieved thanks to the voltage and current sensors that pick up the information and send to the platform for interpretation.As compared to other works, the owner is instructed on what to do in order to maintain the system based on the information the platform has received from the sensors.The designed system is very efficient.Energy access leads to improve livelihood and socio-economic benefits.The module is reliable and affordable.In future works, we intend introducing wind energy to design a hybrid system working monitored with the same principle.

Fig. 4 .
Fig.4.Simulation of the system using Proteus software Fig 4 shows the simulation of the system in the Proteus environment.The Arduino Uno is the central unit of the system associated with other units performing specific functions.The system works with the platform shown in Fig 5, developed using the XoJo software.