Alternative Energy: Solar Energy

2.1 Solar Energy

Solar energy is one of the cleanest sources of alternative energy. Due to high energy demand and environmental negative impact of fossil fuels, many countries consider the alternative energy sources as a suitable and feasible option in industry and domestic usage. Even though coal and hydro generation will continue to be the main energy sources for base load power generation, the decentralized untapped renewable energy sources such as, bio-gas, solar photovoltaic, solar thermal, biomass gasifier, wind power, small hydropower, co-generation, etc. are increasingly gaining importance (Dudhani et al. 2006). Solar energy becomes the center of attention with the nature of being clean, safe and abundant in nature. Most solar energy

This is attributed by its chemical and physical properties that are robust, making it suitable for use in a variety of applications at almost all environmental conditions. Among the lead acid battery properties are (Lam et. al, 2004):

a. The self-discharge is among the lowest of rechargeable battery systems.

b. Both electrodes contain only lead and lead compounds as active materials that do not require conducting activities.

c. It has a high cell voltage of 2V.

d. Lead acid technology is cheaper than other technologies. Although its capacity per kilogram is 30 to 40 Wh / kg, lower than other technologies (cadmium nitride (NiCd): 50-70 Wh / kg, Lithium ion (Li-ion): 150 Wh / kg) its price is two to four times less expensive per kWh stored than the Nickel Cadmium (NiCd) and ten to twenty times cheaper than the nickel-metal hydride (NiMH) and

There are few models of batteries which based on electrochemistry modeled as capacitor and resistor network to represent the charging storage capacity. Sheperd model is commonly used in electrochemical model and is used in several forms with some modification to suit the specific battery types. The simplest equivalent circuit models of batteries are the Thevenin battery. Figure 2.5 shows a Thevenin battery model that consists of voltage source E0, internal resistance R, and a capacitor C with resistance R0 in parallel to it. In simulation, the components remain constant and which made that the model were not accurate. In reality the values of the components are a function of several battery conditions like state of charge (SOC), battery storage capacity, rate of discharge and temperature.

For non-linear electrical model as shown in Figure 2.11, it consists of components where their values vary non-linearly that can be determined