Instrumentation for Solar Photovoltaic System Efficiency Monitoring Through Modbus Protocol

Abstract

Energy is the basic requirement for economic stability, prosperity and sustainable life on earth. Energy is produced majorly by non renewable fossil hydro carbon fuels such as coal, oil and natural gas. The need for energy is growing up exponentially and the hydro carbon based fuels cannot fulfill the energy demand for a long time. The excessive use of non renewable energy resources has resulted in energy deficit and pollution. Energy produced by Solar Photovoltaic (SPV) system is clean, they do not use fossil fuels. SPV system does not release any harmful air or water pollution into the environment, do not deplete natural resources, or endanger animal or human health, work for longer time and hence it stands in the forefront of all available green energy sources. The enhanced potential of energy taping through SPV system depends upon various factors such as type of solar cell, availability of soar irradiance, temperature, climate condition, size and type of battery bank, C rating, solar power conditioning unit (SPCU), connected loads etc. The overall energy conversion efficiency of commercially available SPV system varies in between 13-17%. Online monitoring of energy efficiency of SPV system using the state of the art instrumentation through Modbus protocol will help the users in taking various preventive steps by which consistency on increased energy efficiency can be maintained. This paper illustrates the details of instrumentation devices used for developing SPV system efficiency monitoring through Modbus communication protocol and tested with 250W and 500W resistive loads. The total energy delivered to 250W and 500W loads during battery discharge was 3.32 kWh and 3.19 kWh respectively. The efficiency of solar panel as measured by the developed SPY system was 16.74%. The combined efficiency of SPCU and battery bank w.r.t 250W and 500W resistive loads was 75.45% and 72.50% respectively.